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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Skeptical Science News: The Rebuttal Update Project

Cedders at 19:08 PM on 6 October, 2024

I'm glad to read that the articles are getting a systematic refresh. Anything to make the rebuttals more accessible can help effectiveness in countering myths, misunderstanding and misinformation.

There are two reasons I can think of for the new intros. People are looking for shorter tl:dr abstracts. Secondly, information can be too technical for some audiences. Unfortunately it's hard for scientifically literate writers to know what is likely to be misunderstood, deliberately or accidentally (we know frequent examples like Greenland surface mass balance). Is the new text being tested against actual occurrences of myths?

I hope there's no need to delete much text from the passage of time and it can be edited instead. Historical perspectives can help transparency. As a hypothetical example: 'Loss of Arctic sea ice seemed in the early 2010s to be happening far faster than projections, leading some people to conclude at the time that summer sea ice would be virtually gone by 2020/whenever and headlines. Ice loss has since slowed bringing it more into line with projections.'

Just have a think: Arctic Sea Ice minimum 2024. Three degrees Celsius warming now baked in?

Jim Hunt at 10:28 AM on 27 September, 2024

"Ice of this age is now mostly confined to a narrow strip extending from north of Greenland along the north-west edge of the Canadian archipelago."

The most recent PIOMAS thickness data suggests that it is now mostly confined to a small area within the CAA:

https://GreatWhiteCon.info/2024/09/facts-about-the-arctic-in-september-2024/#Sep-21

Just have a think: Arctic Sea Ice minimum 2024. Three degrees Celsius warming now baked in?

sailrick at 13:16 PM on 25 September, 2024

From the World Meteorology Organization's report; The Global Climate 2011-2020

"Reduced sea ice extent was accompanied by a decrease in thickness and volume, although data for these indicators are more limited. There has also been a marked decrease in the extent of ice which lasted for
more than one year.
In March 1985, old ice (four years or more) accounted for 33% of the total ice cover of the Arctic Ocean, but that figure had fallen below 10% by 2010, and in March 2020 it had dropped to 4.4%..
Ice of this age is now mostly confined to a narrow strip extending from north of Greenland along the north-west edge of the Canadian archipelago."

Climate's changed before

Eclectic at 11:22 AM on 21 April, 2024

Spooky @899 , you should not really be surprised ~ since the OP article is referring to Global temperature changes.

Not to the local rapid changes in the boreal icesheet region (e.g. Denmark, Greenland, Alaska : during the last glacial age) as shown in the Bolling-Allerod warming and in the briefer Dansgaard-Oeschger events. Those local northern regions are affected by "sudden" changes in local oceanic currents ~ both smaller & larger (e.g. the AMOC). But that has little effect on the global scale, except when it involves a massive event like the melting of the Laurentide Ice Sheet (i.e. the Younger Dryas).

In India, the Indian Monsoons (to which you allude) show much fluctuation resulting from very small alterations in local temperatures & winds (winds which may bring more oxygen18-rich water) . . . even in the absence of a 30-year climate change.

For global temperature changes, there need to be global-scale changes in albedo / insolation / particulates / or greenhouse gasses.

Welcome to Skeptical Science

Eclectic at 09:45 AM on 4 April, 2024

Cookclimate @118 :-

You are wrong. When the arctic/Greenland ice-sheets melt, that raises the sea level near the equator, and consequently that slows the Earth's rotation. Basic physics. And you are wrong about so very much of the other stuff you posted.

Where do you get all that wrong info from?

Welcome to Skeptical Science

cookclimate at 09:28 AM on 4 April, 2024

CO2 does not cause Earth’s climate change.

It is estimated that it will cost $62 trillion to eliminate fossil fuels, but eliminating fossil fuels will be a complete waste of our tax and corporate dollars, because it will not stop the warming. You can’t stop Mother Nature.

The IPCC (Intergovernmental Panel on Climate Change) frequently shows that temperature correlates with CO2 for the last 1,000 years as proof that CO2 is causing the warming. But if you extend that to the last 800,000 years, the temperature and CO2 lines do not correlate or fit (Figure 14 in Supplemental Data). If the lines don’t fit, then you must acquit CO2. CO2 is not guilty of causing climate change. CO2 does not control Earth’s temperature. The IPCC has not demonstrated any scientific evidence that CO2 controls Earth’s temperature (they only have unproven theories).

The facts:
• Earth is currently warming (it is still below the normal peak temperature).
• CO2 is increasing (it is above the normal CO2 peak).
• Earth’s current warming is being caused by a 1,470-year astronomical cycle.

The 1,470-year astronomical cycle warms the Earth for a couple of hundred years and melts ice sheets primarily in Greenland and the Arctic. It has repeated every 1,470-years for at least the last 50,000 years. It is normal that it would be happening again. It accelerates Earth’s rotation, stopping length of day increases (Figure 9). It warms the Earth. Based on historical data, the current warming should peak near the year 2060 and then it should start to cool.

For more information, see A 1,470-Year Astronomical Cycle and Its Effect on Earth’s Climate,

DOI: 10.33140/JMSRO.06.06.01

and Supplemental Data,
www.researchgate.net/publication/379431497_Supplemental_Data_for_A_1470-Year_Astronomical_Cycle_and_Its_Effect_on_Earth's_Climate#fullTextFileContent

A data scientist’s case for ‘cautious optimism’ about climate change

Eclectic at 21:32 PM on 2 April, 2024

William @4 , @5 :

William, you are again failing to think logically.

The people of the Global North are fairly well accustomed to deal with the cold. ( Even in harsh Greenland during the Medieval Warm Period, the farmers kept their cattle in the barn for 5 months of the year. Later, a 0.5 degreeC temperature cooling did not cause their societal collapse ~ that collapse was due to socio-economic changes.)

The coming problems of further global warming do affect the people of the impoverished "South". The poor cannot afford house airconditioning ~ even if the national electricity prices were halved. And airconditioned barns . . . are a fantasy. Like the idea of solar panels for barn coolers. And most of the poorest are a long, long way from (expensive) transmission lines.

Yes, agricultural scientists have done some good work in breeding for more heat-resistant staple crops. But nature imposes genetic limits, and there is no Get-Out-Of-Jail-Free card to ultimately save the day.

And the increasing sea level rise will also contribute to mass migrations. Think of "border crises" and demagogues ranting against them thar furriners. It will get a lot uglier than now.

William, you are intelligent enough to know all this. Please put aside your Motivated Reasoning, and skip past all the Denial, Anger, and Bargaining (and the Depression stage, too) . . . and move on to the Acceptance that real action needs to be taken against AGW.

Skeptical Science New Research for Week #49 2023

nigelj at 04:35 AM on 10 December, 2023

MS Sweet. Good information to know.

"I note that Dr. Hansen has long held an Earth System Sensitivity of 6 C. The IPCC consensus has been 3C"

The IPCC number is "equilibrium climate sensitivity", a different thing from earth system sensativity as below. Making it hard to compare the two numbers.

"By definition, equilibrium climate sensitivity does not include feedbacks that take millennia to emerge, such as long-term changes in Earth's albedo because of changes in ice sheets and vegetation. It includes the slow response of the deep oceans' warming, which also takes millennia, and so ECS fails to reflect the actual future warming that would occur if CO2 is stabilized at double pre-industrial values.[38] Earth system sensitivity (ESS) incorporates the effects of these slower feedback loops, such as the change in Earth's albedo from the melting of large continental ice sheets, which covered much of the Northern Hemisphere during the Last Glacial Maximum and still cover Greenland and Antarctica)...."

(Climate sensitivity, wikipedia)

We will probably never know any of these numbers for sure because you can't put the planet in the laboratory. (Although I think paleo studies like the one you posted have a lot of credibility - because they are based on real world conditions). But IMHO that uncertainty is not necessarily a crucial problem. Current rates of warming are bad and are having very visible effects, and huge implicatrion in the short to medium term, and so whatever the level of climate sensitivity using whatever definition, we clearly have a huge problem.

2023 SkS Weekly Climate Change & Global Warming News Roundup #44

MA Rodger at 21:23 PM on 8 November, 2023

This Hansen et al (2023) paper was pre-published back in January and did result in a bit of discussion here at SkS. And there was supposed to be a second paper specifically on SLR.

Hansen et al rattle through a pile of stuff, some of which I would agree has merit and some which I find difficult to accept, some very difficult. The high ECS is one of the very difficult ones. (Perhaps the point that the big part of the difference between high ECS values and the IPCC's most likely value ECS=3ºC, [something the IPCC tend not to identify preferring a range of values as in AR6 Fig1.16]: the difference is due to warming that follows the forcing by a century or more. That time-lag is one of the reasons the ECS estimates are not better nailed down and still has its 'fat tail' . It also would give mankind a fighting chance of dodging it.)

SLR is certainly a big subject of concern. It is a long-term problem, multi-century. The equilibrium position for a +1.5ºC is perhaps 3m and the threat of setting Greenland into unstoppable meltdown at higher levels of warming would triple that. I do tend to get irked by the SLR by 2100 being the sole subject of discussion.

Of course, predictions of that 2100 SLR being massive (5m) is one of Hansen's foibles. The worry is, I think, specific to Antarctica and it is a genuine worry. But to achieve 5m by 2100 would need massive numbers of icebergs bobbing around in the southern oceans and result in global cooling. And there is also the awkward point for climatologists that increased snowfall over Greenland/Antarctica could provide a significant reversal of SLR.

The final issue raised by Hansen et al (2023) is the impact of the reduction of aerosols from our falling SO2 emissions. Quantifying the impact of SO2 emissions is not entirely global a thing, so emissions in, say, China may induce more cooling than, say, Europe. But that said, global SO2 emissions data I identify tends to be way out-of-date. The most recent is this one from a Green Peace publication. This shows the reduction in SO2 is well in hand over the last decade. And the CERES data showing EEI does show a drop in albedo (yellow trace in the 2nd graphic) through that period. My own view of these CERES numbers is that they include a lot of bog-standard AGW-feedback-at-work.

SO2 emissions 2005-19

CERES TOA fluxes

There is also the last 5 months of crazy global temperatures (so post-dating Hansen et al's pre-publication). I don't see these as being sign of things to come. I'd suggest it is casued by the January 2022 Hunga Tonga eruption which threw both SO2 and H2O into the stratosphere, the cooling SO2 dropping out leaving the warming H2O to do its thing before eventually it too dropping out.

And the in-the-pipeline thing. Climatology is/has-been saying we need to halve CO2 emissions b 2030, and following the point of net zero in mid century we enter a century-plus of net-negative CO2 emissions. That would see all emissions 2008 to year-of-net-zero removed by human hand and stored away safely. So that is on top of the natural draw-down of CO2 into the oceans. And if we don't do that, it will not be from ignorance of the situation.

CO2 is not the only driver of climate

Eclectic at 05:51 AM on 9 May, 2023

Piotr @73 ,

Wind & ocean currents move heat energy around the planet - and so there is a considerable "averaging" effect on global temperatures. Even today, you do not need thousands of observation stations in order to assess changes in global temperature. Analysis shows that less than 100 stations are needed (if well-distributed, of course) to give a closely accurate picture of conditions.

A so-called Grand Solar Minimum is not actually very grand ~ studies such as Feulner & Rahmstorf, 2010 and Anet et al., 2013 indicate that a GSM produces a global cooling of around 0.3 degreesC. (Other studies indicate slightly smaller changes.) And this is because our Sun is a very stable star, with a very stable output of radiation. Very little variation.

Even the Little Ice Age was not spectacularly cold ~ a global cooling around 0.5 degreesC . . . which had been helped along by a number of cold winters from volcanic eruptions.

There have been periods of decades of marked cooling in the neighborhood of Greenland earlier in the Holocene, as a result in temporary changes in ocean currents. But these had little effect on average global temperature (the planet is big, and there is a vast amount of tropical ocean). The one exception is the millennium of strong cooling (the "Younger Dryas" ) about 12,000 years ago ~ and this was a one-off event produced by the single event of melt/discharge of the Laurentide Ice Sheet situated in Canada.

Piotr, you seem to have a wrong idea about earlier warm periods (of the Holocene) such as the so-called Minoan / Roman / Medieval Warm Period ~ these were only very slight changes, around 0.3 degreesC or smaller. These were only tiny "blips" on the general slow cooling from the Holocene Maximum temperature (slow cooling owing to the Milankovitch Cycle).

Possibly you have been misled by reports based on Arctic region temperature estimates (the Arctic shows bigger swings than the average global temperature).

Arctic sea ice has recovered

Albert22804 at 17:00 PM on 20 April, 2023

The Kinnard has Arctic ice extent increasing from about 750 to 1500 which is an absurdity. Vikings colonised Greenland about 980 and farmed some areas that today are permafrost.

But the graph shows 980 ice extent to be about the same as 1700 and by that time the areas farmed were permafrost.

The graph shows ice extent dropping dramatically from about 1400 but the little ice age was ramping up in 1400, not down.

The graph shows ice extent increasing dramatically from about 1600 but the LIA peaked around 1650-1700 and temperatures have risen sporadically ever since. The Central England Temperature database correlates well with this.

Here is a different reconstruction that shows 1940 Arctic ice to be about the same as

[LINK]

See figure 1b

But the guy was italian and what would they know? See, I can be sarcastic as well.

There is no consensus

Albert22804 at 09:46 AM on 20 April, 2023

"Such low ECS figures would mean the earth's climate should be almost perfectly stable over geologic time (no glacial-interglacial cycles) and we know that's not true."

Rob, believe it or not there are other factors that effect global temperature like, the sun, solar winds, magnetic fields, cosmic rays, transportation and retention and expulsion of ocean heat, volcanic activity above and below water, aerosols, clouds, gravitational pull of other planets, milankovitcg cycles, earth rotation wobble, shifting of poles, etc.

Our current warming cycle started around 1700 as The little ice age peaked negatively and we have been warming sporadically ever since.

its all perfectly normal with many historical precedents in the Holocene and previous interglacials.

1000 years ago Vikings colonised and farmed parts of Greenland that are still permafrost today. How can this be unless Greenland was far hotter than today. etc Etc etc.

But Michael Mann showed us in his model that the medieval warm period and little ice age never existed so all those thousands of scientists that proved they did exist must be wrong.

Arctic sea ice has recovered

One Planet Only Forever at 03:16 AM on 19 April, 2023

Albert @121, 122, 123,

I would be curious to learn what you believe explains the observed Arctic Sea Ice Mass changes since 2012.

In addition to MA Roger's clarification that Arctic Sea Ice volume is not 'trending up', the lack of statistically significant decline since 2012 needs to be considered along with other evidence like the continued significant decline of Antactic Ice Mass (NASA presentation here) and Greenland Ice Mass (ESSD Article here - see figure 4).

The lack of significant continued decline of Arctic Sea Ice Mass (volume) requires an explanation. But the explanation is unlikely to be that 'global warming impacts of human activity have not been significant since 2012'.

The Big Picture

Bart Vreeken at 07:28 AM on 22 March, 2023

Hi Rob @158

When you're willing to read something wrong there is allways a possibility.

The Netherlands benefit from the gravitational effects. What gravitational effect? The gravitational effects of the melting of the Greenland Ice Sheet. Becaurse of these effects we will only see some 12.5% (or even less) of the melting water coming here. That's better then 100%, so there is a benefit.

The KNMI calls this 'neglecteble' and I do agree with that. For they know what they are talking about.

The Big Picture

Rob Honeycutt at 06:58 AM on 22 March, 2023

Bart... "Looks like you still don't understand the topic completely."

Is that another "opinion" of yours, make without doing even a minimal amount of research?

Previously, far up in this thread, you stated that the Netherlands "profits from" (I'm interpreting that to mean "benefits from") the gravitational effects of the melting Greenland ice sheet. The paper that you cited claimed the effect on the Netherlands was negligible over the previous decade, and makes no claims about projected effects.

Are you claiming the author of the paper you cited doesn't understand this topic completely?

The Big Picture

One Planet Only Forever at 06:34 AM on 22 March, 2023

Bart Vreeken @131,

There was no question. I was presenting an understanding based on observations of evidence in your comments. Your presented interpretation of my comments appears to support my observation in my comment @99 that:

"There is a wealth of evidence in Bart’s comment history that appears to indicate that their interests are not Big Picture. Their interests appear to be much smaller/narrower. They appear to be seeking ‘positive perceptions from the perspective of short-term regional interests’."

I have made other comments about the harm of pursuing positive perceptions because it delays learning the Truth about the Big Picture harm being done to the future of Humanity. Arguing for a 'positive, less panicked, perspective' has produced the current serious harm, and risk of more significant harm, to the future of humanity that is presented in the article I pointed to in my comment @130. Another report on that same topic is by NPR "Cut emissions quickly to save lives, scientists warn in a new U.N. report".

The harmful reality you appear try to avoid understanding, even if you present global interpretations, is not altered by speculation based on one year of heavy snow fall on Antarctica and an unsubstantiated perceived correlation between snowfall and sea ice extent, or because Greenland may only melt on its east coast (conclusions you appear to be interested in jumping to).

Also, as I presented in my comment @68, the very negative (panic level severity) of possible outcomes is what the people who benefit most from the harm need to 'mitigate'. It is important to understand that what is referred to as 'climate change impact adaptation' is mitigation required by others because of a failure of harmful people (success from their short-term limited regional interest perspective) to mitigate their harmfulness. And part of how the harmful try to justify being more harmful is by claiming that "It's not that Bad = positive perceptions that the harm is not very significant" or "Harm done is worth it because of the Perceived Positives".

The Big Picture understanding is that it is generally unacceptable to use benefits or potential benefits to excuse harm done or potential harm done. The only case where that 'may be' acceptable is a case where the individual pursuing or obtaining the benefit will be the only one suffering any harm. It does not even apply to a group because different members of a group may obtain different degrees of harm and benefit.

In spite of that undeniable Big Picture understanding regarding the importance of learning to minimize harm and help those who have been harmed, many people today try to excuse continuing to pursue more benefit from being more harmful. And part of their harmful effort is the pursuit of harmful misunderstandings or a focus on 'positive perceptions that minimize the need for helpful mitigation by reducing the perceptions of severity of harm being done' (like claiming that less fortunate people deserve to be less fortunate, or being dismissive of what is happening to places like Bangladesh).

The Big Picture

Bart Vreeken at 05:57 AM on 22 March, 2023

Hi Rob @153

"the gravitational effects from the Greenland ice sheet are not going to reduce the Netherlands' risk from sea level rise."

Looks like you still don't understand the topic completely. I stated that only 12.5% of the meltwater of Greenland comes to the Netherlands. So yes, the gravitational effect does reduce the risk from sea level rise in NL a little.

"You were not the first to create temperature bars on a graph"

When I started with that I hadn't seen it anywhere else. But of course I can't oversee everything. I didn't research the complete Internet then. My remark about the inspriration for the Climate Stripes was just my opinion, just a site remark and not my main message of @131. You make it more important then it was.

The Big Picture

Rob Honeycutt at 05:29 AM on 22 March, 2023

Bart... "You already do."

Yes. I tend to take exception when people accuse others without justification.

I also notice a pattern here where you don't fully research your claims once you've determined what you want to believe. You were not the first to create temperature bars on a graph, and the gravitational effects from the Greenland ice sheet are not going to reduce the Netherlands' risk from sea level rise.

When you make claims like these it's very important to take the time to be thorough and accurate with what you're stating, and I don't see that you're taking the time to do that.

The Big Picture

Bob Loblaw at 23:37 PM on 20 March, 2023

Ah, I see that Bart continues to do revisionist history on the discussions in this thread.

To start, Bart, the next time you make a "wild guess", please identify it as a wild guess.

Your 12.5% wild guess first appeared in comment 44, where you said:

"Do I have to explain basic geophysics here? When the ice in Greenland melts then only 10 - 15% of it will make the sealevel rise in The Netherlands.

No qualifications there - Bart expressed this as a pretty definitive statement. The context (there is that awful word again) was with respect to Bart's attempts to justify his use of a simple extrapolation of current trends to predict sea level rise by 2100, introduced in comment # 27. He doubled-down on that extrapolation in comment #35., where he also mentioned Greenland.

Bart refines the "10-15%" to "12.5%" in comment # 52, where he says:

"Also according to IPCC the addition to the global sealevel rise by Greenland in the SSP5-8.5 scenario in 2100 is 13cm. 12,5% of this comes to the Netherlands, that's 1,6 cm. Not very much to be worried about.

At this point, he is making it appear as if the 12.5% value is "according to the IPCC". Again, no qualifications to the statement, no indication that the context is changing from "according to the IPCC" to "according to a wild guess by Bart Vreeken".

When challenged for a source, Bart posts a link to a diagram (in Dutch) that gives an incomplete explanation. Then in comment #84, he provide another figure with no caption and no source. Eventually he provides more diagrams and (after a request) the original source of the diagram.

And now he finally admits that his 12.5% value was "a wild guess", after spending days trying to make it look like it was a definitive value supported by various sources.

Do you understand, Bart, that by leading these wild goose chases - as other try to understand where your wild guesses come from - you have largely lost credibility here?

The Big Picture

michael sweet at 05:55 AM on 20 March, 2023

Bart Vreeken,

Your post at 87 claims that "michael sweet @72 says my 12.5% was too low,"

Looking at post 72, I make no claims at all. I show a copy of ice lost on Greenland. I do not mention your claim at 12.5% at all. I believe htat I have never mentioned your claim at all.

It is poor argumentation to make obviously false claims.

The Big Picture

Rob Honeycutt at 04:58 AM on 20 March, 2023

Bart @116... You asked, "Yes I do agree with most of that, so whats the point?"

My point is, you're claiming that the Netherlands would see some level of benefit from the gravitational effects of the Greenland ice sheet melting, and that is demonstrably incorrect. Again, as your own citation states, the effect on the Netherlands is negligible. In other words, there would be little or no effect at all.

The Big Picture

Bart Vreeken at 03:50 AM on 20 March, 2023

Rob Heneycutt, back to your original remark @74. There you say

"Hang on. Am I missing something or is Bart actually thinking that the gravitational mass of Greenland is going to pull sea level away from The Netherlands, when it's 3000km away, making their impacts of SLR nominal? Surely not."

Yes, I am actually thinking something like that. But it's a little different. At the moment the gravitational mass of the ice is attracting mass. 3000km is no problem, the influence goes much further. So, because of the ice mass the sea level here is higher then it should be without the ice. When the ice melts a part of this effect is gone, and because of that the sea level will drop here. On the other hand, there's the meltwater that distributes over the ocean. That aspect makes the sea level rise. The sum of these to is slightly positive.

And now you say:

"They're talking about fractions of a millimeter per year. So, at maximum, they're saying the effect around Greenland (deep blue) over the course of the next century would be on the scale of 5 cm, out of a potential of 1-2 meters of SLR."

Yes I do agree with most of that, so whats the point? The 2 m SLR is a bit to wild, KNMI talks about max 1.2 m in 2100.

The Big Picture

Rob Honeycutt at 03:12 AM on 20 March, 2023

Bart... At this point I would highly suggest you thoroughly read the paper you're citing because you're just not grasping what they're discussing. In particular take note of the scale of the maps. They're talking about fractions of a millimeter per year. So, at maximum, they're saying the effect around Greenland (deep blue) over the course of the next century would be on the scale of 5 cm, out of a potential of 1-2 meters of SLR.

The region they refer to (northern Europe including the Netherlands, Atlantic coastline of Germany and along theArctic coastline of Russia [Fig. 2a]) would have a negligible effect, meaning neither net positive nor net negative. In other words, no effect.

Here is a link to the paper so you don't have to look it up again. Please read it thoroughly and carefully.

The Big Picture

One Planet Only Forever at 13:33 PM on 19 March, 2023

I find Bart Vreeken’s comments interesting, but not in the same way that Bart appears to be interested.

My interest is the Big Picture of the future of humanity and the development of sustainable ways for humans to share the limited capacity of this planet to be lived on sustainably, to not be compromised by the impacts of human activity. A significant part of that interest is understanding the possible peak effects of the harmful accumulating impacts of continued fossil fuel use.

Bart @84, starts with: “MA Rodger @82 your quote is about the global sea level rise, not the local SLR.” The set of images Bart presents are about ‘global sea level impacts’ of the loss of ice due to global warming. But Bart’s interest is limited to the impact on the Netherlands of ice loss from Greenland. The other presented ice loss evaluations do not ‘interest’ Bart as much. This selective regional, rather than Big Picture, interest can be observed in many of Bart’s comments.

Bart’s comments @533 and @537 on the recently updated SkS Climate Myth “Is Antarctica losing or gaining ice?” appear to be their first presentation (March 9, 2023) of what they find ‘interesting’. It is essentially the following: The most recent heavy snow fall on Antarctica, rather than all the other history of events on Antarctica, may be indicating the future of Antarctica. Why would that be ‘interesting’? Maybe because of what happens to the Netherlands due to ice loss from Antarctica as shown in the image set of Barts’s comment @84 referred to above.

And in Bart’s comment @560 indicates they live in the Netherlands and are concerned about sea level rise but “We have to monitor Antarctica very well, try to understand how it works, try to predict what will happen. But not with panic, that won't help us.” Their ‘interest’ in the potential that the most recent year of heavy snowfall on Antarctica indicating a very different future is like the claims that the lack of warming after 1998 indicated a very different future than the ‘panic about ending the harmful impacts of fossil fuel use, especially the global warming impacts. Many people tried to claim that post 1998 temperatures indicated ‘the end of the warming that some people were panicking about’. And Bart appears to be doing a similar thing by trying to claim that this recent year in Antarctica is a turning point of behaviour in Antarctica (as Bob Loblaw tried to point out in his comment @534 in response to Bart’s comment @533).

There is a wealth of evidence in Bart’s comment history that appears to indicate that their interests are not Big Picture. Their interests appear to be much smaller/narrower. They appear to be seeking ‘positive perceptions from the perspective of short-term regional interests’.

They may be correct about the interpretation of the Green lines of the images in their comment @84 and @87 ... but their lack of interest regarding the potential peak impacts (way beyond 2100 levels) on places like Bangladesh is what I find “Interesting” (and not in a Good Way). See My comment @68.

The Big Picture

Bart Vreeken at 04:22 AM on 19 March, 2023

Hi Bob Loblaw, I'm afraid you don't understand the figure well.

Above a) you see the mass loss of Greenland where the calculation is based on. It says -166 Gt/yr. This causes a global sea level rise of something like 0,46 mm/yr. Due to the gravitation effect there are places on earth where the sea level rise is less then that, and places where it's more then that. The border between these two area's is the green line on the map between Africa and South America and in the Pacific. So, the Netherlands are in the area with less then 0,46 mm/yr sea level from Greenland, but it's more then zero. Then there is an other line, between yellow en blue. In the blue area there is no sea level rise by Greenland at all. Instead there is a drop of the sea level.

The Big Picture

John Hartz at 02:17 AM on 19 March, 2023

Speaking of Greenland, what is described in the following news article does not bode well for the future of the Greenland ice sheet...

Greenland temperatures surge up to 50 degrees above normal, setting records by Ian Livingston & Kasha Patel, Weather, Washington Post, Mar 8, 2023

The lede for this article:

The record-breaking warmth is raising concerns about melting summer ice.

The Big Picture

Bart Vreeken at 22:30 PM on 18 March, 2023

MA Rodger @82 your quote is about the global sea level rise, not the local SLR.

This is how it works. The Greenland Ice Sheet has a lot of mass, so it attracts sea water. Due to that, the sea level in a large area around Greenland is higher then it should be without the mass of the ice. When the ice starts to melt a part of this effect disappears. So, around Greenland the sea level will drop, not rise. Netherlands are close enough to Greenland to take profit of this effect, but not enough to avoid sea level rise from Greenland completely.

The Big Picture

MA Rodger at 21:42 PM on 18 March, 2023

Bart Vreeken @80,

That is a curious quote about the Greenland contribution to Netherland SLR given the KNMI Report also says on P22:-

The mass loss of the ice sheets of Antarctica and Greenland and glaciers continues unabated. Since 1993, this component has been the largest contributor to sea level rise.

The idea that the melt water from Greenland, part of the largest contribution to SLR, should somehow choose to avoid the seas off the Netherlands is somewhat silly. I think the idea being expressed is that (as explained within the KNMI Report) SLR is not appearing so much off Netherlands due to altered weather in the North Sea and so the 'Greenland melt' is being used in your quote synonymously for SLR.

The Big Picture

Bart Vreeken at 20:35 PM on 18 March, 2023

Bob Loblow @75 you said:

"Another clue for you: losing ice at lower altitudes around the perimeter of the ice sheet, and gaining ice at the higher altitude is Business As Usual for continental ice sheets. There is this thing called "glacial flow" that moves ice from the accumulation zone to the ablation zone"

Well, that's great. Do you really think I would write about Greenland when I didn't know how it works?

My turn then. The mass change of Greenland by year. Cherry-picking? Maybe, but I use all the available data of GRACE. Over a longer period (altimetry data) there is an increase of mass loss. Don't pay too much attention to the trendline, for the data have a lot of noice. But there is a similarity with Antarctica: more snowfall in the last years, caused by less sea ice.

Greenland Mass Change By Year

The Big Picture

Bart Vreeken at 19:48 PM on 18 March, 2023

Thank you michael sweet @72 for the map of Greenland, based on altimetry. I didn't know this one, it's different from what I expected. I was too quick with my map of the SMB anomaly of only this year, it turns out to be untypical. Never the less we don't expect so much contribution from Greenland here. From the KNMI-report we discussed before:

"Many factors have been taken into account in the calculation of sea level rise on the Dutch coast, including the expansion of the oceans due to warming, self-gravitation, the changes in salinity, and the mass loss of glaciers and ice sheets in Greenland and Antarctica. Because the melting of the Greenland Ice Sheet hardly contributes to the sea level rise off the Dutch coast, we expect that the increase here will lag slightly behind the world average."

The Big Picture

michael sweet at 12:36 PM on 18 March, 2023

It is a real phenomenom that when the great ice sheets in Greenland and Antarctia melt that means there is less gravity there and the sea flows away. I remember that around Greenland itself that could be tens of meters less water and more around Antarctia. There are papers describing where in the globe there will be less water and where there will be more water (ths article describes the affect). By looking at the pattern of sea level rise (upthread I posted a map of sea level rise) and seeiing where it is higher and where it is lower scientists can get an idea of where the water is coming from.

Bart Vreeken posted a map upthread, it is probably accurate. They suggested that melting in the Antarctic will result in higher sea level rise than the global average but melting in Greenland will result in less sea level rise than the global average in Holland. Different parts of Greenland affect Holland differently.

There are other effects on sea level rise that are not intuative. The Gulf Stream carries water from North America to Europe. Sea level in Europe is about 1 meter (!!!) hgher than off North America. If the Gulf Stream stopped, sea level in Europe would decrease substantially while the East coast of the USA would flood. Who wudda thunk.

The Big Picture

Bob Loblaw at 11:28 AM on 18 March, 2023

Bart @ 62:

In addition to pointing out what Rob said to you at comment 64 about the error in using Surface Mass Balance, I note that you have also given a map of SMB for a single winter season. Do you not bother looking at the ful captions of the figures you pick up? This one does not need translation from Dutch - it is dated March 16, 2023, and states "Accumulated anomaly since Sep 1, 2022".

You're back to the same basic error that you made in your very first post here at SkS on March 9, regarding Antarctic ice. Treating a single year of data as if it represents a long term trend.

At least you honestly say "...how the Greenland Icesheet reshapes at the moment..." Now all you need to figure out is that "the moment" is not enough to make predictions about the future.

Another clue for you: losing ice at lower altitudes around the perimeter of the ice sheet, and gaining ice at the higher altitude is Business As Usual for continental ice sheets. There is this thing called "glacial flow" that moves ice from the accumulation zone to the ablation zone. You should read about it some time.

The Big Picture

michael sweet at 10:24 AM on 18 March, 2023

Here is a map of surface height change in Greenland. That includes snowfall, melt runoff, ocean melting and iceberg calving.

greenland surface change

The caption reads:

Maps of elevation change from satellite altimetry reveal where the Greenland Ice Sheet is changing mass. Map created using data acquired by the CryoSat-2 satellite radar altimeter. Credit: CPOM

source

I note that the major areas of ice loss are on the west and northwest side of the island, the opposite of Holland.

The Big Picture

One Planet Only Forever at 08:58 AM on 18 March, 2023

The comments have improved my understanding of sea level rise.

Thank you Rob, Bob and Michael.

Though I lack detailed background knowledge regarding sea level rise I feel confident about pointing out that the 'peak sea level rise', not 'sea level rise by 2100', is what the future of humanity will have to deal with.

From an ethical and moral perspective, the people who benefit(ed) most from causing the harmful result should be responsible for paying for the required mitigation and adaptation. The more that they suffer because of the 'mitigation actions to rapidly end the harmful impact' the less they will have to pay in advance for the required adaptations. This avoids the problem of 'benefiting from harm done while evading the consequences of the harm done'.

What is happening today is serious unethical and immoral attempts to make the future impacts worse and avoid paying for the required repairs and adaptations. The 'highest harming' portion of the global population is not building CO2 removal devices now required to bring harmful impacts back down to 1.5 C levels of warming. And that group is also not planning to pay for the required adaptation in places like Bangladesh (or the island nations being submerged).

I will go one step further on the point of the real problem being the peak impact that has to be adapted to. There is uncertainty regarding how much adaptation is 'enough'. As a structural engineer I am very familiar with the requirements for all load resisting aspects of a structure to have a very low probability (less than 2%) that very severe potential future impacts would exceed the performance capability of the aspects of the structure. And aspects of the structure that are Primary, where their failure would cause significant overall structure failures, would have redundant mechanisms that would keep the structure system from collapsing due to the failure of a Primary element.

Sea level rise impacts would be equivalent to impacts on Primary Structure elements. So the sea level rise that the biggest beneficiaries of fossil fuel use in the current generation are ethically obligated to build globally, for all of the inhabited areas affected by the future sea level rise that they benefited from causing, would be the 'peak sea level increase' that has far less than 2% chance of being exceeded.

The big question is not the different evaluations (uncertainty) regarding the ways that Greenland and Antarctica will respond to human caused global warming. The big question is: What level of warming is almost certain to be the maximum level of the harmful human impacts.

The Big Picture

Bart Vreeken at 08:07 AM on 18 March, 2023

@60

"You have no justification for saying that the mass loss will come from the southern part of Greenland."

When we look at the anomaly of the Surface Mass Balance of Greenland of this moment then I think that it gives a good idea of how the Greenland Icesheet reshapes at the moment. The lower parts and the southern parts are losing ice, and the higher part can gain ice due to more precipitation.

Greenland SMB anomaly March 2023

The Big Picture

Bob Loblaw at 07:33 AM on 18 March, 2023

Bart @ 57:

Yes, I could use Google Translate, but why should I? You are the one trying to make a case here, and if you can't be bothered to provide proper references, proper indications of what you expect people to see in those references or diagrams, then why should we make the effort to guess at what you are trying to show us?

Now that you have provided a translation of the caption and some of the text for the figure that shows "the magical 12.5% figure", I see that the main text says "the rise in the Netherlands could amount to 60% of the global average sea level rise". No 12.5% there, and a direct refutation of your 12.5% claim.

What about the caption? It says that the map is showing "the consequences on the Dutch coast of the disappearance of ice in different parts of the Greenland ice sheet".

The values on that map range from maybe -30% to over +45%. You stated "The mean value of the southern half of Greenland is someting like 12,5%. My assumption is that the mass loss in this century will come from the southern part."

So, that diagram does not demonstrate that sea level rise in The Netherlands from Greenland ice melt will be 12.5% of the global average. The 12.5% value is a value you picked out of the figure purely on the basis of that's what you want to believe. You have assumed your conclusion.

Once again, you have no scientific basis for your claim. You have no justification for saying that the mass loss will come from the southern part of Greenland.

It is obvious that you are just making stuff up, with a smattering of out-of-context quotes or diagrams, with no real understanding of any of the processes.

The Big Picture

Bob Loblaw at 05:21 AM on 18 March, 2023

Bart @ 44:

do I have to explain basic geophysics here? When the ice in Greenland melts then only 10 - 15% of it will make the sealevel rise in The Netherlands. That's due to the self gravitation of the ice sheet.

You have yet to say anything in any of your comments here that represents anything that you can teach me, but let's start with you explaining what you think makes The Netherlands any different from any other part of the globe that is a long way away from Greenland?

Do you actually think that the people that do sea level rise for a living are missing some aspect of geophysics that only you understand? Do you actually think that they do not know about the factors affecting regional patterns of sea level rise? That's the way you are coming across.

The Big Picture

Bart Vreeken at 01:42 AM on 18 March, 2023

michael sweet @ 39

I took my figure (@35) from exactly this report. And here you find an overview of all the different kind of sea level projections (april 2022):

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2021EF002576

Bob Loblaw @40

do I have to explain basic geophysics here? When the ice in Greenland melts then only 10 - 15% of it will make the sealevel rise in The Netherlands. That's due to the self gravitation of the ice sheet.

Antarctica is gaining ice

MA Rodger at 01:05 AM on 10 March, 2023

Bart Vreeken @533,

You appear to be plotting out the GRACE/GRACE-FO data as per this NASA web page (which shows data to Oct 2022). This gravity data does not measure Sea Ice which is floating. And for clarity, it is not Surface Mass Balance which you correctly say had an exceptional year last year (as per this NSIDC post of January 2023, snowfall being high enough to "completely offset recent net ice losses from faster ice flow off the ice sheet for this assessment period. Most of the past decade has seen annual net losses of 50 to 150 billion tons."

Antarctic Surface Mass Balance

So a record year for the 2023 Antarctic Sea Ice Extent minimum as well as a record year for the 2022 Antarctic Surface Mass Balance.

Antarctica doesn't get a lot of attention, compared to the Arctic cryosphere. Certainly for Antarctic Sea Ice, the mechanisms driving the variations is a lot less straightforward in the Antarctic.

Temp record is unreliable

Eclectic at 21:55 PM on 27 September, 2022

Wongfeihung1984 @524,

please ask your friend to study how earlier regional temperatures were demonstrated by changes in Oxygen18 / Oxygen16 ratios (as in ice-cores drilled at Greenland & Antarctica) or Magnesium/Calcium ratios in marine sediments (or Strontium/Calcium ratios, likewise). Those, plus many other proxy measures of temperature in the natural world. can be brought together to give a fair guide as to past conditions.

It would be interesting to know if your friend has greater expertise in scientific matters, and can give a better accuracy than the usual knowledgeable scholars who study the topic extensively. From your description, the word "skeptic" is not what your friend qualifies as.

What’s going on with the Greenland ice sheet?

MA Rodger at 23:09 PM on 3 September, 2022

Wayne @4,
I was in two minds on continuing our interchange, but I decided I would continue when I came across coverage of the paper underlying this SkS OP which surprisingly appeared today on the pages of my local rag with the title "Zombie ice to raise global sea level". On-line I see the same story getting into newspapers elsewhere (eg The Washigton Post).

In terms of an SLR-CO2 correlations, I don't recall seeing Hansen provide it. I believe the closest he got was in Hansen et al (2013) 'Climate sensitivity, sea level and atmospheric carbon dioxide' (with its well-used Fig 1) which looked at temperature & SLR but only inferred CO2 levels with very cursory checks to actual CO2 reconstructions.

Hansen et al (2013) fig 1
And for me, Hansen's 5m SLR by 2100 was always a bit of theorising that I struggled with. Even after it appeared properly written up in Hansen et al (2016), which at least answered the energy equations that were my initial objection to such a large SLR projections, for me it still remains more 'discussion document' than a full-blooded argued case. In my view, worrying as it is, the future SLR from Greenland & Antarctica depends on the Precipitation minus Ice-Loss balances and that puts us in the hands of climatologists for the precipitaion and glaciologists for the ice-loss. The application of paleoclimatology and whether Greenland melted out in the Eemian isn't so relevant for our future SLR.

Just to throw in my other SLR bug bear which also becomes relevant here, I've always reckoned SLR ain't gonna stop at 2100. So why do we go on so long about the 2100 SLR when by 2150, 2200, 2300 etc it's going to be seriously bigger? (A total of 2.3m SLR/ºC AGW according to IPCC AR5 fig13.14.)

The SLR-ΔCO2 relationship is of course a paleoclimate thing, so may not be immediately relevant outside the Eemian or now we have a Panama Isthmus connecting N&S America. That said, the SLR-ΔCO2 relationship is usually a step beyond what most graphics provide, but fig 6 of Rea et al (2021) 'Atmospheric CO2 over the Past 66 Million Years from Marine Archives' does provide us a ΔT-SLR-ΔCO2 graphic. Note that they do not attempt to be definitive with this CO2 reconstruction, saying "While each method has uncertainties, these are largely independent, so their broad convergence on similar CO2 histories is encouraging."
Rea et al (2019) fig 6

But I stress the idea that paleoclimate stuff should concede precedence to glaciology when it comes to the melting ice caps today and glaciology is where the paper underlying the SkS OP above comes from, Box et al (2022) 'Greenland ice sheet climate disequilibrium and committed sea-level rise'. I read that paper as saying that, as of now (2000-19), Greenland is not tipped over into melt-out mode (which I think was always seen as requiring a little more AGW to do that tipping, but nonetheless is good news to hear said) and that the Greenland melt which we are committed-to will happen in the next several decades, not several centuries, and will be mainly over by 2100.

So at least for Greenland under the AGW so-far, my bug bear (that we are in denial ignoring massive SLR awaiting us post-2100) is assuaged.

Mind, the SLR thus awaiting from Greenland isn't trivial. And there is still Antarctica. And not forgetting we still have the tiny task of halting future AGW.

Antarctica is gaining ice

Andrew LB at 07:26 AM on 20 June, 2022

"Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence) (see Figure SPM.3). (4.2-4.7)"

NASA Study in 2015 clearly states Mass Gains of Antarctic ice sheet are greater than losses. I'll quote it.

A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice.

According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008. https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses

On a separate personal note, having lived less than a 2 minute walk from the pacific ocean for the past 40 years, i have yet to see any rise in sea level. One of the docks near my home has pole marked to indicate the current tide height and it's been there for at least 30 years, and a zero foot tide is still indicated spot on all these years later.

I think a lot of the people on this site are unaware of their own motivations and almost religious adherence the government mandated narraitive. It's usually a good idea to actually listen to the people in charge of international climate policy and you'll realize it's all a lie. United Nations climate official Ottmar Edenhofer said the following just a couple years ago.

"One has to free oneself from the illusion that international climate policy is environmental policy. This has almost nothing to do with the environmental policy anymore, with problems such as deforestation or the ozone hole,"

And just a few years prior to that he said:

"the next world climate summit in Cancun is actually an economy summit during which the distribution of the world's resources will be negotiated."

And a bit more insight:

"This is the first time in the history of mankind that we are setting ourselves the task of intentionally, within a defined period of time, to change the economic development model that has been reigning for at least 150 years, since the Industrial Revolution,"

"This is probably the most difficult task we have ever given ourselves, which is to intentionally transform the economic development model for the first time in human history."

And my favorite is how they went on to say that in order to make this happen, they must plunge the world economy into a depression in order to force the end of capitolism.

Antarctica is gaining ice

Shalom Wulich at 22:11 PM on 18 June, 2022

Hi Philippe,

So following the fact that measured data wasnt aligend with the CMIP5 model, now there is new explantation - Good for science!
CMIP6 - you are king !

Were Policy makers aware that in 2014 IPCC CMIP5 got it wrong and now there is a correction with new explanation ? Are they being told of all the corrections ? if so where in the SPM ?

Additionally , if the models then were wrong and now fine tuned, how can we be sure that now they are ok ? what new findings might finetune future models ?

So while we rely on these models to drive policy it might be that in the future, due to these model coming out wrong, we might find ourselves regreting actions we took based on wrong predictions ?

If we go back to 2014 AR5 and review the SPM this is what I make of it:

IPCC - the model predicting Antarctic sea ice got it wrong, lets not include it in the report. If we do include it, it might raise concerns on the validity of the other models we used. Why raise this doubt to begin with ?

Policy makers understanding- Ice is decreasing dramatically all over. Measured data is aligend with models, we go to do something, IPCC is totally right !

Attaching the 2 links showing the Arctic and Antarctic trends measured vs. model and the CMIP5.

Actual Sea trends

The approval CMIP5 model got it wrong

The IPCC used models

and again qouting the key section from IPCC AR5 2014 report:

B.3 Cryosphere

"Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence) (see Figure SPM.3). (4.2-4.7)"

Where is the other trend ? The Antarctic sea ice ???? Ohhhh. That. It's not relevant now.

SkS Analogy 1 - Speed Kills: How fast can we slow down?

Evan at 21:42 PM on 20 February, 2022

Santalives you ask "... is there a problem here?"

Coming out of the last ice-age cycle temperature rose 5C, causing a sea-level rise of 400'. Temperatures have already risen 1.2C and there is enough carbon in the atmosphere, already, to take us to 1.7C. There is over 200' of sea-level rise locked up in the world's ice.

We know that ice melts when it gets warmer and scientists are witnessind destabilization of the big ice sheets in Antarctica and Greenland.

More carbon -> higher temperatures -> more ice melting -> higher sea-level rise -> problem

This is just one of many problems.

How weather forecasts can spark a new kind of extreme-event attribution

wilddouglascounty at 01:26 AM on 15 January, 2022

#18 Eclectic,

Thank you again for your continued discussion, which on the whole has been much more extensive on this thread than I ever expected. I agree that "global warming" and "climate change" have become extremely recognizable in the media and the public around the world, and wanting to replace it with a mouthful of words with nearly the same meaning has questionable merit, so I understand why you are wondering why I want to shift it to what seems to be a subtle point which might be lost on most people. And you may be right.

But there are a couple of points I want to bring up for consideration. The first point is that do you remember when the phrase "global warming" was first popularized, the denialists got a lot of coverage whenever a greenhouse gas turbocharged polar vortex came barreling down from the arctic? Or when the north Atlantic cooling and salt dilution from all the ice melt from Greenland became a thing, potentially causing colder weather for northern Europe, as another example? The climatological community quickly realized that "global warming" did not adequately capture the complexity of changes that were occurring as a result of the changing atmospheric chemistry that were being observed. So "climate change" became the new replacement mantra, at least in the US community. This is an example of how popular terms are changeable, and made more accurate, thereby short circuiting misinformation in the process.

The second point to consider is how the use of steroids has played out in the sporting world. I've used baseball as an example, but steroid use clearly has had its impact across all sports as is evidenced in the Olympics Committee rules development and the increasingly complex monitoring of athletes across all sports. If the conversation in the sporting community just focused on homerun inflation, or increasing serving speeds in tennis, or other sports specific measures, then it would perhaps be harder to connect the dots to reveal the larger cause: steroid use. As we know, climate science has had to look at the much larger net of causality and relationships that impact and are impacted by the increase in the atmospheric greenhouse gas component. The ocean has increased CO2 absorption rates, resulting in acidification. The oceans themselves, not just the atmosphere, is warming, which contributes to sea level rise. The bottom line is that there are several monitoring indexes that are important to watch to understand the impact of greenhouse gas composition in the atmosphere. So just as the sporting community has focused on steroid use as the source of the myriad changes occurring in the sporting community, it makes sense to me to focusing on the source of ocean acidification, sea level rise relating to ocean water temperature, etc. AND climate change: greenhouse gases. It leaves the conversation about whether humanity is causing the problem behind us so we can move ahead with the next steps.

Thanks again for persisting, and I hope that this clarifies why I think it is worth considering this.

Was Greenland really green in the past?

MA Rodger at 22:49 PM on 27 December, 2021

dpc @33,

The original name for Greenland was Inuit Nunaat meaning 'country of human beings'. So perhaps there was once a burgeoning population living there. Or perhaps such names are poor descriptors which would be why, apparently, "people often say that Iceland and Greenland should switch names since Iceland is green and Greenland is so icy."

The new IPCC Report includes – get this, good news

MA Rodger at 19:26 PM on 15 August, 2021

anticorncob6 @1,

The CO2 budgets quickly become very complicated and comparing them takes a little spade-work. Here is my simplistic take on it.

That 2013 Carbon Budget you link to is quite a generous one, even though it is for +2ºC AGW. Its 1,000Gt(C) emissions budget or 3,664Gt(CO2) with an Airborne Fraction of 45% would yield [1,000 x 0.45 / 2.13 + 275ppm=] 486ppm atmospheric CO2 by 2090 (followed by negative emissions). Other Carbon Budgets, for instance the IPCC SR1.5 budget from 2018 set a budget at 432ppm for a 66% chance of avoiding +1.5ºC AGW, this with large negative emissions to follow the reaching of zero. (My assessment here using the simplistic Af=45%.) The AR6 SSP1-2.6 with its 2% annual reductions for a +2ºC AGW, again followed by negative emissions post 2075, I'd assess at something like 285Gt(C) post-2020 so 474ppm, not greatly less than that 2013 Budget you linked to @1. Mind the real wake-up numbers come from AR5 which put the 66% +1.5ºC AGW at 417ppm.

You mention the "positive feedbacks" and perhaps nigelj @2 should have added that land ice will continue melting away unless global temperatures are reduced, the worry being that Greenland will melt down (taking millennia) with warming somewhere between +1.0ºC & +2.0ºC AGW and with nothing to stop it once its summit drops down to warmer altitudes. And the stability of the West Antarctic ice is potentially even more sensitive to warming.

Specific to being "positive feedbacks" (which melted ice fields are not unless they entirely disappear & so reduce albedo), the melting tundra is also a process which will continue for centuries without a return to a chillier climate. The size of such the feedback from melting tundra will depend on how hot we make it.

Keeping the ice sheets intact and the tundra frozen is one of the more obvious reasons why limiting AGW to +1.5ºC is a sensible policy.

Climate's changed before

Daniel Bailey at 01:05 AM on 14 July, 2021

IIRC, the Last Glacial Maximum saw a greater buildup of land-based ice than in previous glacial phases. By the time maximum warming in the Holocene had been achieved and a natural cooling initiated, a great deal of ice remained in Greenland and Antarctica that had already been lost by that same point in previous interglacials.

Given time to reach equilibrium with the modern forcing, global sea levels will eventually surpass any levels achieved in previous interglacials spanning the previous 800,000 years+, and likely far longer than that.

From Dutton 2015, Figure 5:

Skeptical Science New Research for Week #25, 2021

Daniel Bailey at 06:51 AM on 26 June, 2021

Reading the research paper and the Nature commentary on it, they are pretty much in-line with the recent 2019 SROCC (Chapter 4 is most relevant). Table 4.4 gives these numbers:

Don't take my word on it, though. There's a number of discussions out there already (like here and here) saying pretty much the same thing.

For me, the main thing is that they look at the recent research, both the early research by DeConto and the later stuff, which shows that some of the early concerns about marine ice cliff instability were not as bad as originally feared.

“What we found is that over long timescales, ice behaves like a viscous fluid, sort of like a pancake spreading out in a frying pan. So the ice spreads out and thins faster than it can fail and this can stabilize collapse. But if the ice can’t thin fast enough, that’s when you have the possibility of rapid glacier collapse.

There’s no doubt that sea levels are rising, and that it’s going to continue in the coming decades. But I think this study offers hope that we’re not approaching a complete collapse – that there are measures that can mitigate and stabilize things. And we still can change things by making decisions about things like energy emissions, methane and CO2.”

Does this mean that the land-based ice sheets of Antarctica and Greenland may not hold some SLR surprises in store for us? Of course they might. But without a magic crystal ball or a time machine to know with certainty what emissions pathways society will follow in the future, we have to go with what they physics of ice sheets informs us. This research does not rule out worse results this century than the SROCC delineates.

As scientists Joelle Gergis and Richard Alley told a group of us at a recent AGU meeting, the current models (CMIP3 and CMIP5) treat the land-based ice sheets of Greenland and Antarctica as "like rocks, but painted white". Meaning that they were not coupled or interactive with their surroundings in any climate-related way. The CMIP6 models, however, look to more fully couple those ice sheets with their surrounding ocean regimes.

Society will have an enormous difficulty in dealing with the first meter of SLR, due at some point this century. If it gets a second meter this century (perhaps not globally, but possibly in some regions), that will be catastrophic.

The New Climate War by Michael E. Mann - our reviews

Micawber at 03:04 AM on 8 June, 2021

Michael Mann is correct in thinking that our information is totally controlled by media giants.
Scientists are charged to read their own publications and “peer reviewers” stack the peers so that no new ideas can get through. Rarely if ever do you find references to key earlier work by retired or deceased scientists. I give a few examples.
Microsoft Office still uses years beginning 1 January 1900. They charge for updates but still have a fatally flawed program. Why is he allowed to pose as a scientist and innovator?
Even David Keeling was nearly prevented from continuing verification of CO2 infrared heat blankets by rigged peer review. He gives a vivid account in his autobiographical review:
Keeling, C. D., 1998, Rewards and Penalties of Monitoring the Earth, Ann Rev. Energy Env, 23(1), 25-82, doi:10.1038/nature105981.
Blair Kinsman had earlier shown how the misuse of statistics and inability to take daily validation data could mislead to wrong conclusion. Unlike in lab experiments geophysical data once not taken cannot be repeated at will. This has happened with our gross neglect of near surface ocean data where is located most anthropogenic heat.
Kinsman, B. 1957, Proper and improper use of statistics in geophysics, Tellus 9(3), 408-418, doi:10.1111/j.2153-3490.1957.tb01897.x
Free access sci-hub.do/10.1111/j.2153-3490.1957.tb01897.x
"The dangers facing the earth's ecosystems are well known and the subject of great concern at all levels. Climate change is high on the list. But there is an underlying and associated cause. Overpopulation."
Sir David Attenborough https://www.youtube.com/watch?v=JRPmLWYbUqA
"Can you think of any problem in any area of human endeavor on any scale, from microscopic to global, whose long-term solution is in any demonstrable way aided, assisted, or advanced by further increases in population, locally, nationally, or globally?"
"The Greatest Shortcoming of the Human Race is our Inability to Understand the Exponential Function" Bartlett, Albert A., 1979
www.youtube.com › watch › v=F8ZJCtL6bPs
Wherever humans are involved we HAVE the Weimar greed equation. Better snap up fish stocks, or oil or whatever before someone else grabs it.
Graham Hancock has beeN ridiculed for suggesting there was a great civilisation as early as 400,000 years ago. Yet there are pyramids dated 130,000 years old in the Mississippi basin. Genetics link Oceania to S America. The compact nature of the Antikythera Clock suggest it was used for navigation. Why else would one cram a complete astronomical clock into a case the size of a sextant? The clock could predict lunar eclipses 78 years ahead as well as their colour. Many wheels have prime number of gears to give highly accurate astronomical times. There were even wheels for the Olympic and other games. Silicon valley may think of it as a mechanism or computer. But it was a clock long before Harrison’s. Such sophistication suggests many years development. It clearly could not have sprung up 350BC, any more than modern printed circuits could have been envisioned in 1957.

Sealevels averaged 50m below present in prehistory before 1750AD. There were many rich landmasses where merchant sailors could establish empires. They were wiped out by catastrophic sea level rise both cyclical and from asteroid impacts. We are at the top of earth’s remaining peaks.
https://www.youtube.com/watch?v=bAqqA3fMwI8
Melting ice of Greenland and Antarctica is proceedING exponentially leading to rapidly rising sealevels, floods and storms as well depleted fish stocks.

Waters around Faeroes does not get cold enough for cod and halibut to breed. They need to be at least 10 years old before they start. (netflix seaspiracy)
The north sea herring disappeared before 1950s, the Newfoundland cod in the 1980s. Gunboat diplomacy could not save them.
What do you think we should do? Perhaps include the equatorial undercurrent in climate models?
There has been too much about hot air instead of hot water.
I have not heard Dr Mann mention this. There are none so blind as those who will not see.
There needs to be a real focus on what the great oceans are telling us.

Arctic sea ice loss is matched by Antarctic sea ice gain

Daniel Bailey at 05:40 AM on 4 June, 2021

@Joe Levesque, per NOAA's Arctic Report Card 2017, current Arctic temperature anomalies and low values of Arctic sea ice extent are unprecedented over the past 1,500 years.

Expanding upon that, it's far warmer now in Greenland than it was at any point during the Viking habitation of it. The few Vikings that survived left rather than die there (and the Inuit thrived there the entire time and still do so today).

As a matter of additional fact, it's far warmer now in Greenland than it has been in the past 10,000 years.

Back to you.

Arctic sea ice loss is matched by Antarctic sea ice gain

Eclectic at 15:31 PM on 3 June, 2021

Joe @23 , best if you give much more detail about what you mean.

The Norse settlement history of Greenland is a complex multi-layered course of events. Temperature played little part (the medieval warming was only about 0.3 degreesC above the background).

Social and geo-political changes were the main determinants of the settlement's ultimate failure. All interesting. But the late stage sea-ice increase [and we don't really know if it was particularly big] would likely have been a very minor "straw" on the camel's back, compared with all the other disincentives that the Greenland Norse settlements were facing.

Arctic sea ice loss is matched by Antarctic sea ice gain

Joe Levesque at 14:22 PM on 3 June, 2021

The historical Arctic sea ice reconstruction appears anomalous with the Viking settlements in Greenland In the 10th century. Where they settled then is not habitable today due to ice levels. Anybody up to explain how this can be explained?

Dr. Ben Santer: Climate Denialism Has No Place at Lawrence Livermore National Laboratory

MA Rodger at 22:33 PM on 31 May, 2021

We are now a few days after Koovin's seminar at the LLNL but I don't see a word of the grand message presented by Koonin. Presumably it is as embarassing as his silly book.

Trying to find some coverage of the seminar, I did spot Koonin's pathetic attempt at de-debunking, that is debunking the WSJ Mills' article [LINK-paywalled] that debunked his silly book. Koonin's efforts at de-debunking simply demonstrates the level of utter nonsense you can expect from an obfuscatiing denialist troll like Koonin.

Just holding up the first of the nine items Koonin attempts to de-debunk shows the purile standard. This first item involves the following untruthful quote from Koonin's book which needs little comment to debunk.

"Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago."

Cutting through the nonsense presented by Koonin's de-debunk, the troll defends his grand assertion using Fig 1d of Frederickse et al (2020) 'The causes of sea-level rise since 1900' which shows the 30-year average rate of SLR attributed to Greenland by the study 1910-2010. Koonin tells us:-

"The “fact check” [by Mills] does not refute the statement quoted, which is about the rate of sea level rise 80 years ago."

...

"The 2019 paper by Frederikse et al. clearly shows that Greenland’s contribution to sea level rise around 1940 was about three times higher than it was in the last decades of the 20th century."

Yet, if it is about SLR and not Greenland, then the relevant evidence from Frederickse et al is shown in Fig 1c not Fig 1d. And Fig 1c shows average rate of SLR in 2010 was 33% greater than at any time "eighty years ago" and that "today" it is likely higher again. Greenland is not the sole contributor to the acceleration in SLR (thus a cherry-pick) while Koonin's use of "the last decades of the 20th century" to represnt "today" is no more than disigenuous trolling.

...

And in the intrests of correctness (the troll Koonin may have been saving his best until last), the ninth and last of his de-debunking atttempts to defend the Koonin quote:-

"...while global atmospheric CO2 levels are obviously higher now than two centuries ago, they’re not at any record planetary high — they’re at a low that has only been seen once before in the past 500 million years."

The context of this quote which compares today with "the past 500 million years" is not given. It appears Koonin bases his "only seen once before" comment on CO2 relative to today's 400ppm being lower 300 million years ago. And presmably his grand book does not provide a justification for this comparison. So, as was discussed in the debunking by an actual geoscientist, 300 million years ago the sun was much weaker, this perhaps 1.5% weaker 300 million years ago, so [0.025 x 250Wm^-2 =] 3.75Wm^-2 or the equivalent to a doubling of CO2. Koonin ignores such argument agaist him and instead concentrates on refuting the potential for future CO2 levels reaching 1000ppm.

Overshooting 2C risks rapid and unstoppable sea level rise from Antarctica

Jim Hunt at 20:09 PM on 13 May, 2021

And don't forget Greenland:

https://www.carbonbrief.org/new-climate-models-suggest-faster-melting-of-the-greenland-ice-sheet

And don't forget that here on SkS you have to manually add the hyperlink using the "Insert" tab!

2021 SkS Weekly Climate Change & Global Warming News Roundup #19

Jim Hunt at 18:07 PM on 10 May, 2021

Al @6,

They don't brand Dr. Koonin "a nought but a vacuous blowhard", and it sounds as if they weren't sent a copy of his book for reveiw. However based on a review of the book in the Wall Street Journal the science content has been assessed as "very low" by Climate Feedback:

Scientists who reviewed the article found that it builds on a collection of misleading and false claims. For instance, Koonin states that “Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago”. Contrary to the claim, scientific studies using airborne and satellite altimetry observations show considerable thinning has occurred along the margin of the Greenland ice sheet since 2003. As explained below by Twila Moon, from the National Snow and Ice Data Center, the Greenland ice sheet lost more mass during the 2003-2010 time period than during the entire time period from 1900 to 2003. Furthermore, this melting has generated a measurable sea level rise over the last 20 years.

Koonin also claims that “the rate of sea-level rise has not accelerated”. Contrary to the claim, scientific studies show that rates of global sea level rise have changed over time and accelerated, notably since the 1990s, primarily due to glacial ice melting and the expansion of seawater as it warms. As pointed out by Zeke Hausfather, Director of Climate and Energy at The Breakthrough Institute, sea levels are rising faster now than at any point since records began in the early 1900s

etc. etc.

It hasn't warmed since 1998

michael sweet at 06:18 AM on 21 April, 2021

Vonyisz:

Interesting questions. Most of your questions are answered in other posts here on Skeptical Science.

First I would point out that the OP you are responding to was written in December 2007. Since then, as the OP correctly predicted, the temperatures have risen substantially and no-one seriously claims that the temperature is not increasing any more.

There are indeed many metrics that can be measured for heat content of the entire Earth. Most or all of them are measured. For a general audience, like here on Skeptical Science, the surface air temperature is easiest to explain and relates to peoples lives best. The total ocean heat content (all the way to the bottom) is probably a more scientific measurement but does not relate to people as well. Global warming warms the ocean all the way to the deepest depths. In general, the warming is slower the deeper you go.

I recently saw an article (sorry no cite) that said the surface ten meters or so of land has heated up more than scientists thought. As you point out measuring the heat content of soil is difficult, but scientists make the best estimates thay can. Scientists are contually improving heat measurements. Skilled scientists know these measurements and consider them but for the average man on the street (or woman) the surface air temperature means the most. The surface air temperature is noisier than ocean heat content but people relate to air temperatures better.

I have seen calculations similar to yours about melting the ice in the Antarctic (or Greenland). The point is that if all the ice in the Antarctic melted 65 meters of sea level rise would result!! So if only 0.1% of the Suns energy melted ice it would result in 6 centimeters of sea level rise per year! What a disaster that would be.

It turns out that scientists working full time on these difficult questions can reach fairly good approximations of all these measurements. Sometimes a new measurement changes the picture a little (like the land measurements mentioned above), but overall where the heat goes is well known. If you ask about a single one of the measurements you mentioned above perhaps someone can give you a citation. You have too many questions here to specifically answer them.

Skeptical Science New Research for Week #9, 2021

Rob Honeycutt at 06:33 AM on 15 March, 2021

SunBurst... It's clearly stated in the movie what's being demonstrated is what would happen if all the ice on the Greenland and Antarctic ice sheets melted. An ice-free planet, which we had the last time CO2 levels were as high as today, would have sea levels that are 70 meters higher than today. These are facts.

Peter Brannen's Paleo Proxy Twitter Thread

John Mason at 20:46 PM on 9 March, 2021

I'm sure Greenland was affected during the Eemian given the sea level data.

The East Antarctic ice-sheet is less than 40ma old, dating from approximately the Eocene-Oligocene boundary.

Peter Brannen's Paleo Proxy Twitter Thread

DK_ID at 09:49 AM on 9 March, 2021

@2, you are correct but I didn't think the changes over the last 2 my had much impact on the East Antarctic ice sheet and ocean sediments should be around for over 100 my.

However, there are problems with the impact theory. There are deposits that seem to indicate a bolide impact but studies of paleo-indian population density don't really support the theory. Also, you may know more than me, but I think the 1st evidence found for the YD was from Greenland ice cores. Greenland has, likely, been affected by past interglacials.

Skeptical Science New Research for Week #7, 2021

Rob Honeycutt at 12:12 PM on 19 February, 2021

James... There's the Antarctic ice sheet, the Greenland ice sheet and Arctic sea ice. Did you have one in mind?

Arctic Sea Ice Minimum Volumes Video - 2020 edition

MA Rodger at 17:35 PM on 28 November, 2020

Wilt @2&3,

While we should not be surprised by the appearance of sub-million sq km Arctic Sea Ice minimums (=ice-free) starting sometime in the 2030s (& there has been a fair old kerfuffle with folk suggesting it could be sooner), the usual concern of ice melt and the AMOC is the melt run-off from Greenland which has increased by perhaps 30% in recent decades. (Note this is the increase in gross run-off. The net ice loss (run-off minus snowfall are the more dramatic values we usually see.)

The increased Greenland melt very roughly results in an extra 300Gt of cold fresh water discharged into the oceans which is a tiny change when compared to the 15,000Gt of cold fresh water resulting from the annual melt of the northern sea ice, a level of annual melt that has remained unchanged over the last 40 years. And the arrival of an ice-free summer minimums Arctic Ocean won't immediately change that 15,000Gt melt cycle, not until the arrival of an ice-free Arctic Ocean in the early summer and through to the autumn.

While the AMOC is driven in the most fundamental way by the freezing polar temperatures, its sensitivity to changes in salinity and these cold fresh water inflows is quite local and the Greenland discharge into Labrador & Nordic Seas is the very point of sensitivity.

Climate's changed before

Daniel Bailey at 07:47 AM on 29 October, 2020

@michael sweet

"Then the question is how long will it take for all that ice to melt"

Sea level rise from ice sheets continue to track worst-case (High scenario) climate change scenarios (discussion here, source paper here).

Source

Which, charitably, means 2.0 meters SLR by 2100, given that the Greenland Ice Sheet has tipped into a negative mass balance state, Earth having lost 28 trillion tons of ice in the past 23 years and that Greenland is expected to exceed Holocene loss rates by 2100.

Image Source

Typically, when climate scientists try to understand some of the expected future effects of global warming and climate change, they first look to the past. And in looking to the past, we can use the example of the climate transition from the icy depths of the Last Glacial Maximum into our current Holocene Interglacial to guide us. From about 21,000 years Before Present (BP) to about 11,700 years BP, the Earth warmed about 4 degrees C and the oceans rose (with a slight lag after the onset of the warming) about 85 meters.

However, the sea level response continued to rise another 45 meters, to a total of 130 meters (from its initial level before warming began), reaching its modern level about 3,000 BP.

This means that, even after temperatures reached their maximum and leveled off, the ice sheets continued to melt for another 8,000 years until they reached an equilibrium with temperatures.

Stated another way, the ice sheet response to warming continued for 8,000 years after warming had already leveled off, with the meltwater contribution to global sea levels totaling 45 additional meters of SLR.

Which brings us to our modern era of today: over the past 100 years, global temperatures have risen about 1 degree C…with sea level response to that warming totaling about 150 mm. Recently, accelerations in SLR and in ice sheet mass losses have been detected, which is what you’d expect to happen when the globe warms, based on our understanding of the previous history of the Earth and our understanding of the physics of climate.

Support for above:

https://www.nasa.gov/feature/goddard/2019/study-predicts-more-long-term-sea-level-rise-from-greenland-ice/
https://advances.sciencemag.org/content/5/6/eaav9396

https://climate.nasa.gov/news/2458/why-a-half-degree-temperature-rise-is-a-big-deal/
https://www.nature.com/articles/nclimate2923
https://www.nature.com/articles/ncomms9059
http://www.pnas.org/content/111/43/15296.short
https://www.carbonbrief.org/sea-level-research-says-only-a-brief-window-to-cut-emissions

https://climate.nasa.gov/news/2869/antarcticas-effect-on-sea-level-rise-in-coming-centuries/
https://www.pnas.org/content/110/4/1209
https://science.sciencemag.org/content/364/6444/eaav7908
https://advances.sciencemag.org/content/5/1/eaau3433
https://www.pnas.org/content/116/30/14887

Climate's changed before

Daniel Bailey at 00:29 AM on 29 October, 2020

Since we are discussing sea level rise, recent sea level rise is unprecedented over the past 2,500 years (Kopp et al 2016):

Anthropogenic forcing dominates global mean sea-level rise since 1970 (Slangen et al 2016):

"the anthropogenic forcing (primarily a balance between a positive sea-level contribution from GHGs and a partially offsetting component from anthropogenic aerosols) explains only 15 ± 55% of the observations before 1950, but increases to become the dominant contribution to sea-level rise after 1970 (69 ± 31%), reaching 72 ± 39% in 2000 (37 ± 38% over the period 1900–2005)"

Causes of sea level rise since 1900, from NASA and Frederikse et al 2020:

Takeaways:

1. Glacier-dominated cryospheric mass loss has caused twice as much sea-level rise as thermal expansion since 1900

2. The acceleration since the 1970s is caused by the combination of thermal expansion and increased Greenland mass loss

3. Ocean mass increases from land-based ice losses dominated the early 20th and 21st Century sea level rise record; ocean heating was the dominant component from 1970-2000

4. The closure of the 20th-century sea-level budget derived here implies that no additional unknown processes, such as large-scale deep ocean thermal expansion or additional mass loss from the Antarctic Ice Sheet are required to explain the observed changes of global sea level

Additionally, new research (Miller et al 2020) affirms modern sea level rise is linked to human activities, and not to changes in Earth’s orbit:

"Surprisingly, the Earth had nearly ice-free conditions with carbon dioxide levels not much higher than today and had glacial periods in times previously believed to be ice-free over the last 66 million years, according to a paper published in the journal Science Advances.

“Our team showed that the Earth’s history of glaciation was more complex than previously thought,” said lead author Kenneth G. Miller, a Distinguished Professor in the Department of Earth and Planetary Sciences in the School of Arts and Sciences at Rutgers University-New Brunswick. “Although carbon dioxide levels had an important influence on ice-free periods, minor variations in the Earth’s orbit were the dominant factor in terms of ice volume and sea-level changes — until modern times.”

Sea-level rise, which has accelerated in recent decades, threatens to permanently inundate densely populated coastal cities and communities, other low-lying lands and costly infrastructure by 2100. It also poses a grave threat to many ecosystems and economies.

The paper reconstructed the history of sea levels and glaciation since the age of the dinosaurs ended. Scientists compared estimates of the global average sea level, based on deep-sea geochemistry data, with continental margin records. Continental margins, which include the relatively shallow ocean waters over a continental shelf, can extend hundreds of miles from the coast.

The study showed that periods of nearly ice-free conditions, such as 17 million to 13 million years ago, occurred when the concentration of atmospheric carbon dioxide — a key greenhouse gas driving climate change — was not much higher than today. However, glacial periods occurred when the Earth was previously thought to be ice-free, such as from 48 million to 34 million years ago.

“We demonstrate that although atmospheric carbon dioxide had an important influence on ice-free periods on Earth, ice volume and sea-level changes prior to human influences were linked primarily to minor variations in the Earth’s orbit and distance from the sun,” Miller said.

The largest sea-level decline took place during the last glacial period about 20,000 years ago, when the water level dropped by about 400 feet. That was followed by a foot per decade rise in sea level — a rapid pace that slowed from 10,000 to 2,000 years ago. Sea-level rise was then at a standstill until around 1900, when rates began rising as human activities began influencing the climate.

Future work reconstructing the history of sea-level changes before 48 million years ago is needed to determine the times when the Earth was entirely ice-free, the role of atmospheric carbon dioxide in glaciation and the cause of the natural fall in atmospheric carbon dioxide before humans."

LINK

From the source paper, Miller et al 2020:

"High long-term CO2 caused warm climates and high sea levels, with sea-level variability dominated by periodic Milankovitch cycles.

Sea level rose in the Early Pliocene ca. 4.7 Ma, reaching highs that had not been consistently seen since the MCO. From a sea-level perspective, the Pliocene is marked by three intervals with sea level well (~10 to 20 m) above modern: 4.6 to 4.1, 3.9 to 3.3, and 3.3 to 2.85 Ma.

GMSL higher than 12 m above modern requires loss of ice sheets in Greenland, West Antarctica, and sensitive areas of East Antarctica, the Wilkes, and Aurora Basins. This interval is of keen interest, because global temperatures were >2°C warmer than today at times when atmospheric CO2 concentrations were on the order of those in 2020 CE (~400 ppm), and thus, the equilibrium sea-level state is relevant to ice sheet trajectories in coming centuries. The peaks between 3.9 and 3.3 Ma were even higher, reaching a peak of ~30 m during Gi13, and thus requiring some melting of the EAIS.

The development of a permanent EAIS by 12.8 Ma resulted in a change from responding to precession, tilt, and eccentricity to subdued to absent response to eccentricity and precessional forcing that had previously been strong; the 41-ka tilt cycle dominated ice sheet and sea-level response from ca. 12.8 to 1.0 Ma following the development of a permanent EAIS. During the mid-Pleistocene transition, very large, 100-ka paced LIS were amplified by 100-ka changes in CO2 from ~180 (glacial) to 280 ppm (terminations).

During the last deglaciation (ca. 19 to 10 ka), GMSL rise exceeded 40 to 45 mm/year, providing an upper limit on known rates of GMSL rise. Rates before radiocarbon ages are less certain, although the sea-level rises exceeded 10 mm/year during terminations. Sea-level rise progressively slowed during the Holocene until the late 19th to early 20th century when rates began to rise from near 0 to 1.2 mm/year in the early 20th century to a late 20th and 21st century rise of 3.1 ± 0.4 mm/year.

Sea level follows long-term trends of atmospheric CO2, with high sea levels associated with high CO2 and warm climates. CO2 played an important role with high CO2 maintaining warmth in the Eocene (with values >800 to 1000 ppm; associated with largely ice-free conditions and high sea levels. Generally, decreasing CO2 values during Middle Eocene to Oligocene led to cooling and glaciation, although a secondary CO2 increase at ca. 35 to 36 Ma may be associated with the late Late Eocene warming. The cause of the CO2 decrease over the past 50 Ma has been widely discussed and debated but must be due to long-term (107-year) changes in CO2 sources (e.g., higher CO2 associated with inferred higher ocean crust production rates) or more likely the effectiveness of sinks CO2 (e.g., increased weathering associated with uplift of the Himalayas or exposure of basalts in tropical regions).

Our records that suggest nearly ice-free conditions occurred during the MCO and are thus intriguing if this is an equilibrium state for warming levels that will be attained in this century or the next century under sustained greenhouse gas emissions.

Our sea-level history constrains cryospheric evolution over the past 66 Ma, with ice-free conditions during most of the Early Eocene, MECO, latest Eocene, and possibly the MCO, with ice sheets (up to 40-m sea-level equivalent) in the Middle to Late Eocene greenhouse and with continental-scale Antarctic ice sheets beginning in the Oligocene.

From 34 to 13.8 Ma, the EAIS varied from larger than today (sea-level ~35 m below present) to nearly ice-free (~50 m above present) but became permanent during the MMCT ca. 12.8 Ma."

Miller 2020, Figure 4, rotated once:

And the past 40,000 years, from Miller 2020, Figure 4 above:

Miller 2020

Climate's changed before

MA Rodger at 20:36 PM on 28 October, 2020

Eclectic @861,

"That graph" of Holocene SLR you reference (referenced also @860 & pasted in-thread @843) is a bold piece of work found within Wikipedia and is based on the following:-

Fleming et al (1998) 'Refining the eustatic sea-level curve since the Last Glacial Maximumusing far- and intermediate-field sites',

Fleming (2000) 'Glacial rebound and sea-level change : constraints on the Greenland ice sheet', a 300 page thesis with download PDF available from this webpage,

Milne et al (2005) 'Modelling Holocene relative sea-level observations from the Caribbean and South America' [Abstract].

I say 'bold' as combining the messy Holocene SLR data into a simple grand global average is not entirely scientific although it does prove illustrative. The IPCC AR5 does present a graphic (within Fig 5.15) providing the same sort of image surrounded by a blizzard of other graphical SLR data. This IPCC Fig5.15f is essentially Fig 14 from Lambeck et al (2010) 'Palaeoenvironmental records, geophysical modelling and reconstruction of sea-leveltrends and variability on centennial and longer time scales'.

Climate's changed before

Eclectic at 22:33 PM on 25 October, 2020

MA Rodger @847 ,

thanks for that information. Re late Holocene MSL decline, I must confess I was relying on memory of seeing (several years ago) a graph of the Holocene highstand declining by 1-2m during the most recent 4-5000 years, as the global temperature reduced by around 0.7 degreesC. As you say, I might have been rather faultily recollecting something which lacked land "rebound" compensation.

On the other hand ~ a quick googling turns up SE Lewis et al. (2008) showing an eastern Australian fall in MSL of 1-1.5m over the period 7000-2000 BP. Eastern Australia (excluding Tasmania) had very little burden of ice sheet at the last glacial maximum (to rebound from) . . . and Australia has been tectonically relatively stable, as well ~ so it is a useful basis for Holocene MSL trends.

I think I may be misunderstanding your IPCC reference where: "Ocean volume between about 7 ka and 3 ka is likely to have increased by an equivalent sea level rise of 2 to 3 m." If the lagging effect of Holocene warming produced a likely 2-3m MSL rise over the period about 7000-3000 BP . . . is that inconsistent with a 1-1.5m MSL fall in the last 3000 years? [Assuming some fuzziness/uncertainty in the Lewis et al. dating]

As a matter of interest, I did a quick back-of-envelope calculation: indicating that for a 1m fall in MSL, the depth of ice on Greenland/Antarctica would need to increase by about 30m. This ignores oceanic thermal contraction and glacier expansion in non-polar regions.

Climate's changed before

MA Rodger at 19:50 PM on 25 October, 2020

Hal Kantrud @845,

There is certainly a timelag between temperature rise and ice loss and with big ice sheets the lag can also be big (but not necessarily). The current level of AGW is put at 1ºC and the sea level rise so far at 20 or 30 cms. Yet the anticipated sea level rise per 1ºC AGW is put at 230cm over a period of a couple of millenia. But additional to that 230cm/1ºC is Greenland which maintains its ice sheet solely becuse its summit is high up surrounded by cold atmosphere. It is anticipated that somewhere between 1ºC and 2ºC of AGW, the summit of Greenland's ice will drop into an unstoppable melt-out as the summit decends into warmer atmospheres, this adding a further 600cm to sea level over perhaps ten millenia. I say "unstoppable" in that it would require a return to ice age conditions to stop the melt and build the summit back up into colder airs.

Regarding the chopping down of woodland, this is globally not New World.

Climate's changed before

MA Rodger at 22:21 PM on 24 October, 2020

Hal Kantrud @842,

To address your three requested points of clarification/confirmation.

(1) The only actual continent-sized ice sheet is Antarctica and that remains unaltered in size through an interglacial and through a glacial maimum. The glacial maximum see the growth of ice sheets across the northern half of N America, Greenland and N Europe. The Greenland ice sheet has survived the present interglacial but was melted out in the previous one.

The impact of small wobbles in global temperature is not significant within this process as the temperature change is small and it doesn't last very long. The ice melt is a slow process. Thus, while global temperatures stopped rising 10,000 years ago, the melt continued strongly for a further 2,500 years and less strongly for another 4,000 years, this shown by the sea level record.

Sea level holocene

(2) Your timings are a little off. After the Holocene peak temperture (best considered as a plateau 10,000y to 6,000y bp), global temperature has been dropping but only to the equivalent of 11,000y bp. 13,000y bp would have you back in the Younger Dryas event when it was very cold.

(3) The CO2 record from ice cores does show previous interglacials with CO2 (& CH4) levels falling quickly from the peak of the interglacial. This is not the case for the present interglacial when CO2 (& CH4) levels are shown to rise not fall. This has led to some interesting work setting out the idea that the activities of mankind are responsible for this early rise, for CO2 perhaps dating back to 8,000y bp (& 5,000y bp for CH4).

While this work remains speculative, the CO2 (& CH4) levels through this interglacial would act to slow the drop back into a glacial maximum.

The unprecedented CO2 levels likely now top the CO2 levels seen 3 million years ago (this was back when N America was joined S America at Panama and initiated the Arctic ice) and are thus uprecedented in 13 million years, thus back to a time when weathering of the newly-formed Himalayas caused reducing CO2 levels.

....

And addressing your main question which concerns the CO2 levels of the last few centuries rather than those of the late stone age because any increase pre-industrial cannot be the result of fossil fuel use.

According to the Global Carbon Project, the anthropogenic CO2 emissions since pre-industrial amount to some 650Gt(C) of which 450Gt(C) results from fossil fuel use and 200 Gt(C) due to Land Use Change, but note this is mainly cutting trees down not "the conversion of New World grasslands".

Scientists remember 'Koni' Steffen, glaciologist who died after fall into crevasse in Greenland

Doug Bostrom at 05:52 AM on 18 August, 2020

Steffan's most recent publication Greenland surface air temperature changes from 1981 to 2019 and implications for ice‐sheet melt and mass‐balance change (coauthor) is here:

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.6771

Open access.

Scientists remember 'Koni' Steffen, glaciologist who died after fall into crevasse in Greenland

Bob Loblaw at 22:39 PM on 17 August, 2020

I just read about this in today's Globe and Mail (story attributed to the New York Times news service).

https://www.theglobeandmail.com/world/article-konrad-steffen-who-sounded-alarm-on-greenland-ice-dies-at-68-2/

Everything You Need to Know About Climate Change

Bob Loblaw at 11:20 AM on 15 July, 2020

William's description of the terminology is in agreement with my understanding.

Ice ages are times when there is long-term ice ice in some locations on the planet, and we currently have such ice in mountainous regions as well as Greenland and Antarctica. We are in an ice age.

During an ice age, periods with extensive ice are "glacial periods", and periods will relatively little ice are "interglacials". We have much less ice now than during the last glacial maximum; we are in an interglacial.

The mis-use of the term "ice age" is pretty common.

It's only a few degrees

michael sweet at 07:44 AM on 11 July, 2020

Jasper,

I am surprised that students in the Netherlands are not concerned about sea level rise. In the last ice age the temperatures were about 5C less than the current temeperatures. The sea level was 125 meters lower than it is today! From "only" 5C temeprature change!!! The current IPCC estimate for 2100 is a little over 1 meter sea level rise. Dutch engineers think they can manage 1 meter sea level rise. The high estimates of sea level rise by 2100 are well over 2 meters. That would overwhelm the Dutch dykes! What do farm boys think of that?

Have the students check the estimates for sea level rise from all 5 IPCC reports. Every report the sea level estimate is increased! Currently the temperature response of the great ice sheets on Greenland and the Antarctic is not well understood. Some sea level experts think that 6 meters of rise by 2100 is possible if the ice sheets respond rapidly. (To my students I emphasize the high end of the IPCC. The IPCC estimates are low compared to other scientific estimates). If you post again I can look for other estimates for you.

I had my students (the same age as yours) write me a report on the Arctic sea ice minimum in September. The NSIDC web site is easy to read (unfortunately in English). The summary of the yearly low in sea ice will be posted about October 7. The retreat of sea ice does not raise sea level. On the other hand, it is right next to Greenland which does raise sea level. My students were invariably shocked at the rate of sea ice loss.

I had my students write another report on global temperature using the NOAA web site. This is also easily read in English. The summary of yearly temperature will be posted about January 15 2021 for the year 2020. There is probably a web site in Dutch (any readers know of a Dutch site?) but I like the NOAA web site a lot.

Post again if we can help you.

It's only a few degrees

MA Rodger at 21:00 PM on 30 June, 2020

Jasper @3, Yet another take.

You write "I get that a few degrees make a huge difference. I don't fully understand why a few degrees matter so much." Although a huge difference is suggestive that it does matter, I read your meaning that you are after an authoritiative take on the effects of "a few degrees" and something with a bit of meat on it.

Warming the globe by "a few degrees" will make a big difference to the climate system which has been previously reasonably fixed for millenia and so will bring unprecedented change for human civilisation. But providing an authoritative account of what that change will amount to isn't so easy.

Will those "few degrees" be enough to stop the AMOC and plunge Europe into a mini-ice age, enough to broaden the Hadley Cells and turn the central US lands and the Mediterranean lands into deserts, to green the Sahara and turn the Amazon into a treeless savannah? The answers are not straightforward. There is no long list if definitive outcomes set out in the headlines of the IPCC AR5 Synthesis Report. The word "risk" features too often when IPCC describes such outcomes.

IPCC AR5 SYN SPM Fig8

But there are a couple of definitive temperature-related outcomes from AGW.

One is that Greenland will melt out somewhere between +1ºC and +2ºC threatening serious sea level rise. (The IPCC AR5 puts the upper bound at +4°C which is rather a fudge. Antarctica's ice caps are similarly a threat but how quickly they will react to global temperature rise is not well enough understood to be so predictable.) Another is the habitability of the tropics for humanity and perhaps a third is ocean acidification which would be unprecedented in tens of million of years.

If Greenland were to melt down (a process that once started will not stop as the top of the Greenland ice sheet today sits happily frozen high up in the cold upper atmosphere), the oceans would rise by over seven metres. This compares with the last six thousand years (which spans the period of human civilisation) when changes in sea level could be measures in centimetres. A seven metre rise would be a big problem as so much of our populations today live close to sea coasts. (About a third of humanity inhabit land less than 100 metres above sea level while the loss of both Greenland and Antarctica would raise sea levens 75 metres.) The melt-down of Greenland would take a few centuries to make its mark but the process certainly becomes unstoppable if global warming remains two degrees centigrade above pre-industrial.

The "few degrees" global temperature rise that accompanied the warming from the last glacial maximum 20,000 years ago and the dramatic impact on climate has been mentioned up-thread. The change in climate resulting from another similar-sized rise in global temperature would be just as dramatic for humanity. If global temperatures rose by six degrees celsius above pre-industrial, it could perhaps be described as a "Steam Age" as the increase in wet bulb temperatures would make the tropics a death trap for humans outside air conditioning. And such a six-degree temperature increase by 2100 is within the projection of the Business-As-Usual scenario of the IPCC.

The ocean acidification would rival that of the PETM 55 million years ago but would happen in decades rather than tens-of-millenia.

There is a big pile of reason not to let AGW run beyond +1.5°C. The implications for humanity and for much of the biosphere will be catastrophic if we let AGW run. It's a bit like jumping off a cliff. Predicting the height it would require for the fall to split your skull open is not straightforward but that is no reason to consider jumping. Besides, when you fall it's the intracranial hypertension that usually kills.

2020 SkS Weekly Climate Change & Global Warming News Roundup #25

Eclectic at 20:06 PM on 22 June, 2020

Lawrie @9 , Slarty Bartfast maintains that there is no global warming of any significance at a statistical level or at a physical planetary level. So to him, albedo is irrelevant.

Being more than 24 hours since his last posting, it seems unlikely that Slarty will return to attempt rebuttal of criticisms of against his many positions. But we can hope he will return, to give a grand explication of his apparent errors and inconsistencies.

In order to save the valuable time of SkS readers, I have looked further into Slarty's blog of May / June 2020 , and I have pulled out some points of interest. Slarty's statistical/mathematical skills are (IMO) far exceeding his climate science knowledge . . . and somehow I am reminded of the very emeritus & climatically-challenged Ivar Giaever !

I have taken some care not to misrepresent or quote-mine Slarty. And please note that Slarty, in his blog, describes himself as: physicist / socialist / evironmentalist.

1. Sea level rise cannot be more than slight , because there is no CO2-AGW or CO2-led Greenhouse effect. And so our coastal cities have zero danger of submersion.

2. What little CO2-greenhouse effect is present now, is produced by CO2 reflecting IR back to the planetary surface.

3. Weather stations fail to give valid planetary data because they are far too few, and (just as importantly) they are not evenly spaced.

4. "temperature records just aren't long enough ... to discern a definite trend ... you need at least 50 years."

5. "[land ice] In Antarctica (and Greenland) this is virtually all at altitude (above 1000 m) where the mean temperature is below -20 C, and the mean monthly temperature NEVER gets above zero, even in summer. Consequently, the likelihood of any of this ice melting is negligible."

6. AGW forcing does not supply enough heat to melt ice at the poles [he seems to include the Arctic, too].

7. The Arctic is not warming. [Presumably news to those alarmist Inuit who live there.]

8. Berkeley Earth Study repeats the sins of Hadley/ NOAA / etc but in a more transparent way ~ and BEST generates a falsely-positive warming trend through its misuse of Breakpoint Adjustments (rather than using raw data).

9. Slarty's oceanic thermal expansion calculations are wrong [as pointed out by MA Rodger].

And there's more !

Ice isn't melting

Daniel Bailey at 06:24 AM on 28 April, 2020

Per Velicogna et al 2020 - Continuity of ice sheet mass loss in Greenland and Antarctica from the GRACE and GRACE Follow‐On missions:

Both the Greenland and the Antarctic Ice Sheets continue to lose ice mass from April 2002 through September 2019.

Greenland Ice Sheet average mass loss:

Antarctic Ice Sheet average mass loss:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087291

Ice isn't melting

MA Rodger at 20:09 PM on 27 April, 2020

Lawrence Tenkman @11,

The Ocean Heat Content measured down to 2000m is increasing at a rate in excess of 10Zj/year due to AGW. The global loss of ice mass is subject to a lot of variation year-to-year but to put some numbers down:-

Sea Ice Arctic Sea Ice loss (from PIOMAS) averages 350Gt/y since 2007. Antarctic Sea Ice Volume is poorly assess but probably insignificant. (The small Antarctic areal increase to 2004 graphed in the OP was very minor. It became more pronounced for a while 2014-16 before plunging negative where it remains. The graph here is from NSIDC.)

NSIDC Arctic Antarctic SIE

Land Ice The dramatic acceleration of polar land ice in the OP graphs has not been maintained. With GRACE-FO beginning to give results (graph of Greenland mass balance), the recent combined rate of loss of global land ice has been assessed as something like 650Gt/year.

So the global ice loss is roughly 1,000Gt/year.

In terms of the energy to warm the resulting melt water up to average ocean temperatures, something like +4ºC, would require 0.015Zj/year, significantly less than the 10Zj/year annual increase in OHC. Energy to warm melt-water is also significanlty less than the energy required to convert that amount of ice into the melt-water (0.30Zj/year) but ocean-wise that would only affect icebergs melting out while bobbing on the briny sea.

Where all this melt water will play more of a role in global climate is it being fresh water and not briny. Note that the Greenland rate of gross ice loss is probably five-times greater than the rate of net ice loss and there is a lot of other fresh water entering the oceans from rivers and also the annual sea ice melts, but fresh water is more buoyant than ocean water and increases in the discharge of fresh water into the oceans can disrupt deep ocean currents, the AMOC (which brings warmth to the high Atlantic) being of particular concern.

YouTube's Climate Denial Problem

nigelj at 12:28 PM on 12 April, 2020

duncan61 @34, you claim some data supports sea level rise and some data says there is more ice, so presumably no sea level rise. You give no details or examples or sources.

Sea level rise is measured by both tidal gauges and satellite and they both unequivocally show sea leve rise. Satellites are also able to monitor the mass balance of ice sheets and show Greenland is losing ice dramatically and Antarctica is losing ice slightly. Glaciers are also monitored and most are losing ice. If you just bothered to read the appropriate information under secptical myths on the left side of this page you can get some details.

Now the denialist side of the debate typically make claims that glaciers are advancing, but if you read carefully they refer to just a small subset of glaciers, or they say sea ice is increasing somewhere when this doesn't actually affect sea level rise so its not relevant. Or they say Antarctica is not losing ice or much ice, while not mentioning that plenty of other places are. Or sometimes the denialists data is just made up.

None of this is new, in fact its now almost ancient history. I have several times explained these sorts of climate things diplomatically but you dont seem to get it. I cannot make you understand if you can't or won't, and I can't teach you critical thinking skills if you cant or wont.

We have tidal gauges and satellites and historical photos and god knows what all pointing to melting ice and sea level rise and its very hard for me to believe these systems of measurement and observation would all be 100% wrong because so many differerent monitoring systems show the same thing. I equally find it hard to believe its all some conspiracy. But perhaps you are built differently.

Personally I think you are just trolling for attention, and that you will come back with a whole lot of silly data.

How I try to break climate silence

One Planet Only Forever at 02:40 AM on 12 March, 2020

Regarding my comment @8,

The following set of links are the specific ones I find are helpful, hard to dispute:

... and particularly that increased CO2 from the burning of fossil fuels could become a significant influence: I initially refer to Wikipedia History of climate change science. If there are questions about Wikipedia’s validity, I refer to the SkS History of Climate Science. That is a well-presented alternative to Wikipedia that has matching content and adds reference to “The Discovery of Global Warming” by Spencer R. Weart, and the Timeline webpage on the American Institute of Physics website.

Evidence of recent increase in levels of atmospheric CO2: NOAA Greenhouse Gas Website (also shows trends for CH4, N2O and SF6)

Evidence of recent increase of global average surface temperature: NASA/GISTemp data set, (I refer to the SkS Trend Calculator if the person wonders about other temperature data sets, and I discussion the difference between surface temperature data and satellite data)

Evidence of recent reduction of Arctic, Antarctic and Greenland ice extents and mass: NSIDC, particularly the Arctic Sea Ice News and Analysis page.

Rising sea levels due to warming of oceans as well as loss of ice, not just Antarctica and Greenland: NASA Sea Level Change.

Sustainable Development Goals

UN Department of Economic and Social Affairs DESA

SDG Knowledge Platform

1972 Stockholm Conference page of the history of Sustainable Development (part of the SDG Knowledge Platform)

How I try to break climate silence

One Planet Only Forever at 12:03 PM on 10 March, 2020

A long comment with details added for anyone interested.

My starting point, or foundation, is “Try to Help Others and Do No Harm”, with the awareness that Everybody’s actions combine to become the future. And being aware that compromising on understanding and its helpful application, or compromising on the required corrections, is understandably harmful.

I think it is essential for people to learn to be as helpful as possible and as harmless as possible. That means personally expanding awareness and improving understanding and applying what is learned to help develop sustainable improvements, and helping others do that. And voting helpfully, and helping others vote more helpfully, is a key part of that individual action.

Rather than provide examples of what I do I will share the basics of the approach I try to use to help others expand their awareness and improve their understanding and apply that learning to be less harmful and become more helpful. It is a work in progress, but this is its current form. (A recent example would be my comments on the “Silk Road article”).

A bit of personal Background:

I try to stick to the fundamentals of constantly improving awareness and understanding regarding any issue and applying what I learn to try to help others and avoid harm being done or reduce the risk of harm. I learned that was the foundation of being a Good Engineer. And it was reinforced by my MBA education which I pursued out of interest in expanded awareness and understanding to be helpful, not in order to get richer quicker.

My MBA education in the 1980s, and my engineering career, taught me that misleading marketing can be temporarily effective but eventually fails, so Good Managers should not use it. My MBA education also taught me that there were very few case studies of Businesses that were Helpful Good Ethical participants in society. Seems that the pursuit of popularity and profit can compromise good understanding and helpful intentions.

I live in Alberta, Canada. I often encounter people who don’t get climate science and the required corrections of developed human activity. Many appear to resist getting it because getting it would require them to give up beliefs and actions that they have developed a liking for.

What I try to do when given an opportunity to discuss climate change:

The following is an Idealized outline of my approach to a comment that initiates the opportunity to discuss human climate change impacts. I try to follow it to avoid getting sucked into a foundation-less argument. I also try to not ‘match the attitude’ of the person I interact with if they start to get angry. That can be difficult because mimicking is a good thing in an interaction when we are collaborating, but the Fight side of Fight or Flight seems to wire us to mimic the increased aggressive behaviour of the person we are engaged with.

I Start by establishing that:

Everyone’s actions add up to become the future. This is key to inoculate against beliefs that Others should act first, especially that totally incorrect but very common demand that the Chinese and Indian populations are the climate change impact problem, rather than understanding that per-person impacts are the point. It also blocks someone from claiming the freedom to believe and do as they please because one person’s actions are no big deal.

Improved awareness and understanding applied to help develop sustainable improvements and reduce harm done is a Governing Objective. This ties to my primary interest in raising awareness of the Sustainable Development Goals (all of the SDGs), and the key importance of limiting human climate change impacts.

I see little point in further discussion without this fundamental awareness and understanding being established.

I then try to establish the following points of understanding, based on the source information I refer to (I am careful about referring to the IPCC or SkS. Many people seem to have developed an impulsive dislike of the IPCC and SkS, especially in Alberta):

In the 1800s there was the initial development of awareness and understanding that GHGs in the atmosphere increase the temperature at the surface of the planet, and particularly that increased CO2 from the burning of fossil fuels could become a significant influence: I initially refer to Wikipedia History of climate change science. If there are questions about Wikipedia’s validity, I refer to the SkS History of Climate Science. That is a well-presented alternative to Wikipedia that has matching content and adds reference to “The Discovery of Global Warming” by Spencer R. Weart, and the Timeline webpage on the American Institute of Physics website.

Evidence of recent increase in levels of atmospheric CO2: NOAA Greenhouse Gas Website (also shows trends for CH4, N2O and SF6)

Evidence of recent increase of global average surface temperature: NASA/GISTemp data set (I refer to the SkS Trend Calculator if the person wonders about other temperature data sets, and I discussion the difference between surface temperature data and satellite data)

Evidence of recent reduction of Arctic, Antarctic and Greenland ice extents and mass: NSIDC, particularly the Arctic Sea Ice News and Analysis page.

Rising sea levels due to warming of oceans as well as loss of ice, not just Antarctica and Greenland: NASA Sea Level Change.

If I get agreement on those fundamentals, I bring up the Sustainable Development Goals and the understood need to achieve all of them through individual action, particularly getting individuals to vote for parties that will try to achieve the SDGs, all of them. And I point out that stopping climate change impacts of human activity is a major helpful action, because more significant human caused climate change makes it harder to achieve almost all of the SDGs.

I then return to discussing the fundamental objective of learning to help develop sustainable improvements and learning to stop harmful actions, tied to knowing that Everybody’s actions add up to the future (negatives if they are harmful). And I try to make the point that there is no neutral position. There is no harmless bystander. Harm is harm. It is not balanced by doing good. A rare exception is trying to help an individual in a way that may harm them – the medical intervention dilemma. Aside from that type of rare Ethical dilemma all other considerations are pretty simple Do No Harm, and Try to Help Others.

How I bring up climate change when given an opportunity to discuss any of the Sustainable Development Goals (there is so much covered by the SDGs that there are many opportunities for this type of discussion):

I use an approach that is similar to the climate change one above:

Start by pointing out that Everyone’s actions add up to become the future. And Improved awareness and understanding ….

Raise fundamental awareness and all of the SDGs, and the history of development of awareness and understanding that resulted in the SDGs: WWI – League of Nations (failure) WWII – UN, Universal Declaration of Human Rights (still a battle to have embraced and honoured by all Leadership) – everything since including Millennium Development Goals and SDGs.

Once agreement of importance of achieving all of the SDGs is established introduce the importance of stopping human climate change impacts because climate change makes achieving the SDGs so much harder.

Regarding how people vote:

I find it challenging to get people I encounter to consider changing their vote. Even if I can get a person to understand and agree that the threat of climate change impacts requires significant corrections of what has developed popularity and profitability, it can be very difficult to get them to change what party they vote for. Many people in Alberta are motivated by the wealth that they have developed a liking for obtaining from the export of fossil fuels combined with the comfort, convenience and enjoyment they can get from using fossil fuels.

The majority of people in Alberta seem to have develop a liking for a certain type of political group based on uncritical identification, particularly just needing to see the Name Conservative or the political position being commented on as Right-wing (that type of party was Alberta’s leadership from 1931 through to 2015, and it returned to power in 2019). The recent time when a non-Conservative party won the leadership happened because there were two well-known Conservative Right-wing parties almost evenly splitting the Conservative/Right-wing votes (though the winning NDP did get a significant number of votes).
And many of those Conservative supporters seem uninterested in investigating the helpfulness/harmfulness of the current set of actions and intentions of the political group they developed a liking for. Their natural inclination is to resist change. And that can be powerful enough to make them resist learning, resist fully correcting or expanding their awareness and understanding. Even getting them to be very concerned about climate change may not be enough to get them to change who they vote for. Some of them seem so ‘identity locked-in’ that they may dislike many of the current actions and plans of the party they developed a liking for, but they will still support it, accepting and making-up poor excuses for the harmful cheating actions and incorrect misleading claims made by Their Party because, well, it is Their Party and they want it to Win, they resist changing their mind (much like sports fans can excuse harmful cheating behaviours by Their Favourite Teams).

I have tried to help them understand that the party they are supporting may have harmfully changed from what they developed a liking for. It may have moved to embrace the support of harmfully self-interested people and that change will damage the Brand they like to identify with. To be fair, many of them probably like their Party because of a harmful self-interest, but they are unlikely to openly admit it.

Based on reading international political news I am quite sure that this also occurs with Right-wing parties and supporters in other nations. You may get them to understand climate science and the identified required corrections, but you are unlikely to get them to vote for a party that is not Conservative/Right-wing. And good luck getting them to succeed in pushing Their Correction Resistant Party to disappoint a significant portion of the Party’s dedicated motivated relied-on voter pool – all those who have a self-interest in personally benefiting as much as possible from the actions of the Party they support, especially the really rich supporters.

Skeptical Science New Research for Week #9, 2020

MA Rodger at 20:31 PM on 6 March, 2020

swampfoxh @1,

Your question doesn't 'ring any bells' with me and the authors you mention don't seem to lead anywhere that I can see.

The 1,500 year timescale is occasionally mentioned as the time it takes the ocean waters to re-appear at the surface and so reach CO2-quilibrium with the atmosphere. That is part of what Goreau (1990) 'Balancing Atmospheric Carbon Dioxide' addresses but it is not the same as timescales for temperature equilibrium under otherwise-fixed CO2 levels.

Rohling is the lead author of Rohling et al (2009) 'Antarctic temperature and global sea level closelycoupled over the past five glacial cycles' and this does consider multi-millennial equilibrium timescales but this concerns sea level. There is a connection in that the melt-out of, say, Greenland would both impact sea level and temperature as the albedo change constitutes a slow climate feedback (see this SkS post). But over such multi-millennial timescales with Milankovitch cycles in operation, it would require more than "modest" climate forcings to be significant.

More directly addressing your question, the ice cores do show a small increase in CO2 levels over the last 8,000 years. This would provide roughly a 0.3Wm^-2 climate forcing which (slow and fast feedbacks so perhaps a sensitivity of 6ºC) could have given a total temperature rise of +0.5ºC. Yet spread over eight milennia, any residual effect today would be now miniscule.

CO2 graph 10000 years

Earth is heating at a rate equivalent to five atomic bombs per second

MA Rodger at 21:44 PM on 16 February, 2020

rip71749,
Regarding the energy from burning fossil fuels, there is an SkS graphic illustrating the relative size of the various global energy inputs.

I feel that 3.7Wm^-2 figure requires some further explaining. It is the value of Climate Forcing, the global energy imbalance, that would result from a doubling of CO2 which, without feedbacks, would result in a global temperature increase of +1ºC. These values are explained by the solar warming (less albedo) being globally 240Wm^-2 which thus gives an effective planetary temperature of (240/5.67e-8)^0.25 = 255K. Add 3.7Wm^-2 and it becomes 256K. These values, of course, apply high up in the atmosphere but the temperature increase from any forcing also applies to the surface temperatures as the lapse rate acts in a linear fashion down through the atmosphere.

Additional to the initial forcing, there are feedbacks which increase the warming. They act as the global temperature rises, this temperature rise meaning the initial climate forcing is being equalised. Thus the feedbacks do not appear as an increased energy imbalance but instead extend the temperature effect of the climate forcing as it equalises with rising temperature.

Now, at any particular time during AGW (where the Climate Forcing is applied slowly over a period and not all at once) the energy imbalance which is warming the globe (and so theoretically available to melt Greenland ice) will be far smaller than the accumulative Climate Forcing since pre-industrial times. Much of this Climate Forcing (and as negative forcings are poorly defined, the value of net Forcing since pre-industrial is imprecisely known but it is usually quoted as very roughly 2Wm^-2) will have been balanced by the global temperature increase since pre-industrial. It is solely the remaining energy imbalance that is available for melting ice caps, this running presently at something like 1Wm^-2.
From the imbalance, there is then perhaps something like 16ZJ/year entering the climate which, if it could be brought to bear on Greenland's ice, would melt Greenland in something like 50 years. Of course, getting all that energy imbalance to Greenland would be impossible but if the ice were to set off across the oceans, it does become possible. Indeed, having melting icebergs bobbing about at lower latitudes would lower the global temperature and this will increase the global energy imbalance. (This is the mechanism behind the hypothesis set out in Hansen et al 2016.)

Hope all that makes sense.

Earth is heating at a rate equivalent to five atomic bombs per second

michael sweet at 07:02 AM on 15 February, 2020

RIP71749,

In general it is a waste of time to do your own calculations. You will be much better informed by reading more peer reviewed papers. Articles at SkS are a good place to start.

As for the melting of Greenland I saw a calculation once but cannot find it to cite. I get very different numbers than you.

First of all, you cannot use the Boltzman equation to calculate the energy absorbed so you are off at the start.

I will use 2, 850,000 km3 of ice which is the same as yours. I get 2.685E21 cm3 of ice. Times 330j/gm times 0.9g/cm3. That is 8E23 joules absorbed to melt the ice (ignoring the energy to increase the temperature) close to your number (did you account for the lower density of ice compared to water? please show your work).

You calculate the energy absorbed by using the energy imbalance of 3.7 W/m2 times the surface area of the Earth of 5.1E14m2 =2E15w times the number of seconds in a year (3E7) = 5.7 E22 joules per year absorbed. It would take about 10 years to melt all the ice in Greenland. If more CO2 is released the energy imbalance will increase and the speed of ice melt increases.

I might have a mistake since the calculation is not peer reviewed. I remember the calculation as showing the energy to melt Greenland was absorbed in a single year but it was a very long time ago and I probably remember it incorrectly.

This number can be GOOGLED if you look hard enough.

Earth is heating at a rate equivalent to five atomic bombs per second

rip71749 at 03:50 AM on 15 February, 2020

Thank you MA Rodger. I have been trying to educate myself on CC over the past few years, pretty much working in a vacuum, on my own. I'm not quite clear on your energy balance from the 1oC increase in temp. Your 3.7Wm ^-2 seems reasonable as a new equilibrium loss to space of energy from the extra energy gained from the greenhouse effect. I view the CO2 levels as a savings account that pays out interest in heat (currently paying 1oC each year, but not carried over). Because we add an extra small amount of CO2 each year we get an extra 'small' amount of extra heat, that slowly accumulates over the decades, centuries etc (so maybe we will reach 2oC, 3oC or higher this century). Of course not all of that heat is from CO2, but its additional effects on ocean H2O (and possibly CH4 from warmer permafrost and peat). So the extra energy seems to me to be calculatable from the Stefen Boltzmann Law, as I did above. It seems to me the sun comes out every day and warms the earth according to the 'current' conditions of the earth and currently that is running 1oC warmer than recent centuries. The large energy value does not seem unreasonable given that the entire earth is warmed 1oC higher. As I understand it we are getting about (0.7)x(342 W/m^2) = 240 W/m^2 from the sun and the 3.7 W/m^2 you mention above is the new equilibrium value from the extra energy of the greenhouse effect. I am assuming that we are leaking more energy than recieved at any particular moment because some of the incoming energy is 'saved' in its warming effect from the greenhouse gases. I'm not sure why my delta = 6 W/m^2 value is not valid and my 200/1 ratio is not accurate. My calculation really does not say anything about how the 1oC increase came about, but the extra energy does seem correct (to me). A CC denier could claim that the extra energy was from Milankovitch cycles or sun spots ot cosmic rays or something else, but those seem to have been discounted from what I have read. To me, it seems the extra energy added from burning all the fossil fuels each year seems pretty trivial (the 200/1 ratio). The problem energy is the energy from the greenhouse gases (H2O, CO2, CH4, etc) absorbing IR radiation and bouncing it around the atmosphere before it reaches equilibrium on its way out to space.

Also, I did do a calculation on how fast the Greenland ice could melt with temperature increases of earth of 1oC, 2oC and 3oC. I assumed there was 680,000 miles^3 of ice. I assumed it started at -1oC to calculate the energy to heat it 1oC (to compare with the energy to melt it all). The heat capacity of ice is about 2.1 joules/(gm oC) and I got a value of 5.8xx10^21 joules. Next, I caluated the energy to melt the ice using a heat of fusion of 334 joules/gram and came out with a value of 9.3x10^23 joules. Because melting is so much more energy I ignored any warming of the ice from lower temperature and only used the energy to melt the ice. I compared that with my energy calculated to warm the earth 1oC (1.0^23 joules), 2oC (1.9x10^23 joules) and 3oC (2.9x10^23 joules). I estimated that the area of Greenland was 1/280 the area of earth and used that to 'crudely' estimate the amount energy available to warm the ice in Greenland with those above energies from 1oC, 2oC and 3oC. My thinking is 9.3x10^23 joules to melt the GL ice divided by (1/280) of the extra energy from 1oC (or 2oC or 3oC) increase in energy. So I came out with 2600 years to melt GL ice with 1oC increase in temp, 1370 years to melt GL ice with 2oC increase and 900oC with 3oC increase in temp. I'm guessing that we will see at least a 3oC increase in temp (or higher, since we are not doing anything), so I went with the 3oC increase. Also, I have read that we are heating the Arctic 2-3 times faster than the rest of earth. If we assume a 24 foot sea level rise from the GL ice and simplistically plot out a straight line for 900 years we would see a 2.7 foot rise in sea level by 100 years, 2120 (or 2.1 foot rise in sea level by 2100). Those seem pretty conservative estimates because I did not consider any melt from the west Antarctic sheet or from pumped out ground water from around the world.

I am sorry for deluge of estimations, but this has been bottled up inside me for a few years, since I am working on my own, and I'm jumping at the chance that you can provide some feedback in case I am going off the tracks. This is the first time I have posted on Skeptical Scientist, but the 'atomic bomb' reference caught my attention since I had also used a Hiroshima atomic bome as an energy ruler. Also, I had read the Hiroshima abomic bomb was 12,000 tond TNT (called little boy) and the Nagasaki was 15,000 tons of TNT (called fat man), so that may be the difference in size of atomic bombs. The biggest US nuclear bomb was castle bravo at 130 Megatons in 1954. The Russian created the biggest nuclear bomb ever, the Tsar Bomba in 1961, at 50 Megatons (the heigth of the blast actually reached the edge of earth/space, over 211,000 feet). That's a whole other problem. Again, I thank you for the taking the time to provide feedback.

CO2 lags temperature

Eclectic at 22:50 PM on 2 February, 2020

In reply to commenter "Map" , from the other thread :-

Map, we must be careful to avoid semantic problems/confusions, so it is best if we all communicate in the standard scientific language (i.e. meaning of terms). You will mislead yourself if you use terms such as "minor ice ages" every 21000 years and "major ice ages" every 43000 years. For that is not what the well-established Milankovitch theory indicates. (See ice-albedo , CO2 feedback, etcetera.)

You haven't said exactly, but you seemed to be referring to Greenland ice cores (such as GISP2 from central Greenland). Their data comes from local conditions ~ not from global temperature changes.

There have been interestingly large/rapid swings in temperature shown in GISP2 data, but these are are mostly around the unusual event of the Younger Dryas . . . and do not reflect a basic global climate change (nor the inflow/outflow of heat energy which is the underlying cause of climate change).

For the sudden rise you mentioned, please permit me to quote climate expert Richard Alley :- "[temperature increase was] for Greenland, and applies moderately well around the North Atlantic, primarily as a wintertime change because there was a rapid shift from wintertime sea ice to wintertime open water in important regions. ... I can provide lots of chapters and verses on all of this, but the skinny version is that when the abrupt shifts happened, they primarily involved circulation rather than greenhouse gases, they didn't do a lot to global mean temperature, but they did do a lot to regional climates in many places, with large, rapid changes in North Atlantic temperatures, rapid shifts in monsoonal rains and in the edges of the tropical rain belts, smaller shifts in northern temperatures away from the North Atlantic, and lagged and opposite shifts in southern temperatures (so northern warming was followed by southern cooling)".

Map, I hope that provides you somewhat of a help. Please note that the big swings in the GISP2 proxy temperature data . . . are often displayed in the Deniosphere (of science-denying websites) ~ where it is implied that it's a world temperature chart. Worse, the GISP2 graph ends at 1855 (yes, eighteen fifty five ~ quite before the modern AGW temperature rise began) . . . and the chart scale is so compressed, that the casual reader is misled into believing past temperatures were much higher than modern times.

Denialist websites, such as WattsUpWithThat [WUWT] are well-known for these types of deceptions & falsehoods. Map, if that's where you've been getting some of your information/misinformation . . . then you have been handicapping yourself. WUWT contains all sorts of propaganda ~ and a lot of mutually contradictory crackpottery . . . and the comments sections there are half-filled with people who are still in complete denial of the basic physics of CO2 radiational properties. Really a snake-pit of intellectual insanity !

CO2 lags temperature

michael sweet at 20:27 PM on 2 February, 2020

MARodger,

Thank you for the reference to the 2006 report in NASA's Earth Observatory, they do say 15F in 10 years. When I found their referenced source of the GISP2 temperature and accumulation data (file did not open on this computer, sorry for no link), the data is all sectioned off in 50-80 year sections so a 10 year claim is not supported. In addition, 15F would be about 8C and there is no change anywhere near that magnitude (in 50 years not 10) in the record. It seems to me that the NASA report has a typo in it.

To address Map's question, this is data for a single location on Greenland and not global data. The temperature change in Greenland was over 20C since the last ice age while Earth average was 4C according to the data in the OP. In addition. there is much more noise in data from a single location than from an average for the entire Earth. Conflating Greenland data for the Earth's average is simply incorrect.

You ask several questions in your last post. It is difficult to respond to several questions separated only by a question mark. Please ask one at a time. Start with the one that is most important to you.

1934 - hottest year on record

Map at 15:52 PM on 2 February, 2020

I was not trying to imply, I am imploring. How is one supposed to learn when a question is deleted as "gosh gallop"? The quote that I had posted was listed in a few diffent sources that I have looked at. I do believe eclectic is correct that they were mostly in reference to Greenland's ice core analysis, however they are still prevelant in this discussion as they refer to a previous time of global warming because excess co2 was found in the core samples with an unknown source of why the co2 was that high. How is that not relevant to today's global warming if we are again seeing a rise in temperature due to co2? Why should that question be dismissed? What caused the rise in co2 to balance out 20000 years ago and slow the global warming back then without humans?

1934 - hottest year on record

Eclectic at 12:26 PM on 2 February, 2020

Philippe ~ yes, sorry about that effort on your part.

Our good commenter "Map" was perhaps referring to the local regional temperature changes shown in Greenland's GISP2 ice core during the transient fluctuations of the Younger Dryas . . . and he was trying to imply that they were global climate changes "inexplicable by mainstream climate science". My first thought was that he might have been a newbie, grossly uninformed on the topic . . . though there was a wiff of sly science-denialist argumentativeness in his wording. And the latter case has become more evident (only much less sly! ) .

I am sure I am not telling you anything new in all this, Philippe. I just wished to put it on the record, for later readers who come along.

Sea level rise is exaggerated

Daniel Bailey at 09:28 AM on 1 December, 2019

"When I look at the graphs and tables for each island/islands, I find that the graphs are uniformly even and NOT showing increases in sea level."

Not sure what your definition of "uniformly even" is. Did you expect them to be so?

Firstly, global sea level rise is a global average and the surface of the oceans are anything but level (the surface of the oceans follow the gravitic shape of the Earth and are also subject to solar, lunar, sloshing and siphoning effects and oceanic oscillations, etc, all of which need to be controlled for).

From the NCA4, global average sea level has risen by about 7–8 inches since 1900, with almost half (about 3 inches) of that rise occurring since 1993:

SLR

From NOAA STAR NESDIS:

"Only altimetry measurements between 66°S and 66°N have been processed. An inverted barometer has been applied to the time series. The estimates of sea level rise do not include glacial isostatic adjustment effects on the geoid, which are modeled to be +0.2 to +0.5 mm/year when globally averaged."

Regional SLR graphics are also available from NOAA STAR NESDIS, here.

This is a screenshot of NOAA's tide gauge map for the Western Pacific (NOAA color-codes the relative changes in sea levels to make it easier to internalize):

Clicking on the Funafuti, Tuvalu tide gauge station we see that sea levels are rising by 3.74 mm/yr (above the global average) there, with a time series starting around 1978 and ending about 2011:

However, the time series used by your BOM link for Funafuti (1993-2019) is shorter and the BOM also does not apply a linear trend line to it like NOAA does:

Feel free to make further comparisons, but comparing a set of graphics with no trend lines vs those with trend lines is no comparison at all.

From the recent IPCC Special Report 2019 - Ocean and Cryosphere in a Changing Climate - Summary for Policy Makers, September 25, 2019 release (SROCC 2019), the portions on sea level rise:

Observed Physical Changes
A3. Global mean sea level (GMSL) is rising, with acceleration in recent decades due to increasing rates of ice loss from the Greenland and Antarctic ice sheets (very high confidence), as well as continued glacier mass loss and ocean thermal expansion. Increases in tropical cyclone winds and rainfall, and increases in extreme waves, combined with relative sea level rise, exacerbate extreme sea level events and coastal hazards (high confidence).
A3.1 Total GMSL rise for 1902–2015 is 0.16 m (likely range 0.12–0.21 m). The rate of GMSL rise for 2006–2015 of 3.6 mm yr–1 (3.1–4.1 mm yr–1, very likely range), is unprecedented over the last century (high confidence), and about 2.5 times the rate for 1901–1990 of 1.4 mm yr–1 (0.8– 2.0 mm yr–1, very likely range). The sum of ice sheet and glacier contributions over the period 2006–2015 is the dominant source of sea level rise (1.8 mm yr–1, very likely range 1.7–1.9 mm yr–1), exceeding the effect of thermal expansion of ocean water (1.4 mm yr–1, very likely range 1.1–1.7 mm yr–1) (very high confidence). The dominant cause of global mean sea level rise since 1970 is anthropogenic forcing (high confidence).
A3.2 Sea-level rise has accelerated (extremely likely) due to the combined increased ice loss from the Greenland and Antarctic ice sheets (very high confidence). Mass loss from the Antarctic ice sheet over the period 2007–2016 tripled relative to 1997–2006. For Greenland, mass loss doubled over the same period (likely, medium confidence).
A3.3 Acceleration of ice flow and retreat in Antarctica, which has the potential to lead to sea-level rise of several metres within a few centuries, is observed in the Amundsen Sea Embayment of West Antarctica and in Wilkes Land, East Antarctica (very high confidence). These changes may be the onset of an irreversible (recovery time scale is hundreds to thousands of years) ice sheet instability. Uncertainty related to the onset of ice sheet instability arises from limited observations, inadequate model representation of ice sheet processes, and limited understanding of the complex interactions between the atmosphere, ocean and the ice sheet.
A3.4 Sea-level rise is not globally uniform and varies regionally. Regional differences, within ±30% of the global mean sea-level rise, result from land ice loss and variations in ocean warming and circulation. Differences from the global mean can be greater in areas of rapid vertical land movement including from local human activities (e.g. extraction of groundwater). (high confidence)
A3.5 Extreme wave heights, which contribute to extreme sea level events, coastal erosion and flooding, have increased in the Southern and North Atlantic Oceans by around 1.0 cm yr–1 and 0.8 cm yr–1 over the period 1985–2018 (medium confidence). Sea ice loss in the Arctic has also increased wave heights over the period 1992–2014 (medium confidence).
A3.6 Anthropogenic climate change has increased observed precipitation (medium confidence), winds (low confidence), and extreme sea level events (high confidence) associated with some tropical cyclones, which has increased intensity of multiple extreme events and associated cascading impacts (high confidence). Anthropogenic climate change may have contributed to a poleward migration of maximum tropical cyclone intensity in the western North Pacific in recent decades related to anthropogenically-forced tropical expansion (low confidence). There is emerging evidence for an increase in annual global proportion of Category 4 or 5 tropical cyclones in recent decades (low confidence).
B3. Sea level continues to rise at an increasing rate. Extreme sea level events that are historically rare (once per century in the recent past) are projected to occur frequently (at least once per year) at many locations by 2050 in all RCP scenarios, especially in tropical regions (high confidence). The increasing frequency of high water levels can have severe impacts in many locations depending on exposure (high confidence). Sea level rise is projected to continue beyond 2100 in all RCP scenarios. For a high emissions scenario (RCP8.5), projections of global sea level rise by 2100 are greater than in AR5 due to a larger contribution from the Antarctic Ice Sheet (medium confidence). In coming centuries under RCP8.5, sea level rise is projected to exceed rates of several centimetres per year resulting in multi-metre rise (medium confidence), while for RCP2.6 sea level rise is projected to be limited to around 1m in 2300 (low confidence). Extreme sea levels and coastal hazards will be exacerbated by projected increases in tropical cyclone intensity and precipitation (high confidence). Projected changes in waves and tides vary locally in whether they amplify or ameliorate these hazards (medium confidence).
B3.1 The global mean sea level (GMSL) rise under RCP2.6 is projected to be 0.39 m (0.26–0.53 m, likely range) for the period 2081–2100, and 0.43 m (0.29–0.59 m, likely range) in 2100 with respect to 1986–2005. For RCP8.5, the corresponding GMSL rise is 0.71 m (0.51–0.92 m, likely range) for 2081–2100 and 0.84 m (0.61–1.10 m, likely range) in 2100. Mean sea level rise projections are higher by 0.1 m compared to AR5 under RCP8.5 in 2100, and the likely range extends beyond 1 m in 2100 due to a larger projected ice loss from the Antarctic Ice Sheet (medium confidence). The uncertainty at the end of the century is mainly determined by the ice sheets, especially in Antarctica.
B3.2 Sea level projections show regional differences around GMSL. Processes not driven by recent climate change, such as local subsidence caused by natural processes and human activities, are important to relative sea level changes at the coast (high confidence). While the relative importance of climate-driven sea level rise is projected to increase over time, local processes need to be considered for projections and impacts of sea level (high confidence).
Projected Changes and Risks
B3.3 The rate of global mean sea level rise is projected to reach 15 mm yr–1 (10–20 mm yr–1, likely range) under RCP8.5 in 2100, and to exceed several centimetres per year in the 22nd century. Under RCP2.6, the rate is projected to reach 4 mm yr-1 (2–6 mm yr–1, likely range) in 2100. Model studies indicate multi-meter rise in sea level by 2300 (2.3–5.4 m for RCP8.5 and 0.6–1.07 m under RCP2.6) (low confidence), indicating the importance of reduced emissions for limiting sea level rise. Processes controlling the timing of future ice-shelf loss and the extent of ice sheet instabilities could increase Antarctica’s contribution to sea level rise to values substantially higher than the likely range on century and longer time-scales (low confidence). Considering the consequences of sea level rise that a collapse of parts of the Antarctic Ice Sheet entails, this high impact risk merits attention.
B3.4 Global mean sea level rise will cause the frequency of extreme sea level events at most locations to increase. Local sea levels that historically occurred once per century (historical centennial events) are projected to occur at least annually at most locations by 2100 under all RCP scenarios (high confidence). Many low-lying megacities and small islands (including SIDS) are projected to experience historical centennial events at least annually by 2050 under RCP2.6, RCP4.5 and RCP8.5. The year when the historical centennial event becomes an annual event in the mid-latitudes occurs soonest in RCP8.5, next in RCP4.5 and latest in RCP2.6. The increasing frequency of high water levels can have severe impacts in many locations depending on the level of exposure (high confidence).
B3.5 Significant wave heights (the average height from trough to crest of the highest one-third of waves) are projected to increase across the Southern Ocean and tropical eastern Pacific (high confidence) and Baltic Sea (medium confidence) and decrease over the North Atlantic and Mediterranean Sea under RCP8.5 (high confidence). Coastal tidal amplitudes and patterns are projected to change due to sea level rise and coastal adaptation measures (very likely). Projected changes in waves arising from changes in weather patterns, and changes in tides due to sea level rise, can locally enhance or ameliorate coastal hazards (medium confidence).
B3.6 The average intensity of tropical cyclones, the proportion of Category 4 and 5 tropical cyclones and the associated average precipitation rates are projected to increase for a 2°C global temperature rise above any baseline period (medium confidence). Rising mean sea levels will contribute to higher extreme sea levels associated with tropical cyclones (very high confidence). Coastal hazards will be exacerbated by an increase in the average intensity, magnitude of storm surge and precipitation rates of tropical cyclones. There are greater increases projected under RCP8.5 than under RCP2.6 from around mid-century to 2100 (medium confidence). There is low confidence in changes in the future frequency of tropical cyclones at the global scale.
Challenges
C3. Coastal communities face challenging choices in crafting context-specific and integrated responses to sea level rise that balance costs, benefits and trade-offs of available options and that can be adjusted over time (high confidence). All types of options, including protection, accommodation, ecosystem-based adaptation, coastal advance and retreat, wherever possible, can play important roles in such integrated responses (high confidence).
C3.1. The higher the sea levels rise, the more challenging is coastal protection, mainly due to economic, financial and social barriers rather than due to technical limits (high confidence). In the coming decades, reducing local drivers of exposure and vulnerability such as coastal urbanization and human-induced subsidence constitute effective responses (high confidence). Where space is limited, and the value of exposed assets is high (e.g., in cities), hard protection (e.g., dikes) is likely to be a cost-efficient response option during the 21st century taking into account the specifics of the context (high confidence), but resource-limited areas may not be able to afford such investments. Where space is available, ecosystem-based adaptation can reduce coastal risk and provide multiple other benefits such as carbon storage, improved water quality, biodiversity conservation and livelihood support (medium confidence).
C3.2 Some coastal accommodation measures, such as early warning systems and flood-proofing of buildings, are often both low cost and highly cost-efficient under current sea levels (high confidence). Under projected sea level rise and increase in coastal hazards some of these measures become less effective unless combined with other measures (high confidence). All types of options, including protection, accommodation, ecosystem-based adaptation, coastal advance and planned relocation, if alternative localities are available, can play important roles in such integrated responses (high confidence). Where the community affected is small, or in the aftermath of a disaster, reducing risk by coastal planned relocations is worth considering if safe alternative localities are available. Such planned relocation can be socially, culturally, financially and politically constrained (very high confidence).
C3.3 Responses to sea-level rise and associated risk reduction present society with profound governance challenges, resulting from the uncertainty about the magnitude and rate of future sea level rise, vexing trade-offs between societal goals (e.g., safety, conservation, economic development, intra- and inter-generational equity), limited resources, and conflicting interests and values among diverse stakeholders (high confidence). These challenges can be eased using locally appropriate combinations of decision analysis, land-use planning, public participation, diverse knowledge systems and conflict resolution approaches that are adjusted over time as circumstances change (high confidence).
C3.4 Despite the large uncertainties about the magnitude and rate of post 2050 sea level rise, many coastal decisions with time horizons of decades to over a century are being made now (e.g., critical infrastructure, coastal protection works, city planning) and can be improved by taking relative sea-level rise into account, favouring flexible responses (i.e., those that can be adapted over time) supported by monitoring systems for early warning signals, periodically adjusting decisions (i.e., adaptive decision making), using robust decision-making approaches, expert judgement, scenario-building, and multiple knowledge systems (high confidence). The sea level rise range that needs to be considered for planning and implementing coastal responses depends on the risk tolerance of stakeholders. Stakeholders with higher risk tolerance (e.g., those planning for investments that can be very easily adapted to unforeseen conditions) often prefer to use the likely range of projections, while stakeholders with a lower risk tolerance (e.g., those deciding on critical infrastructure) also consider global and local mean sea level above the upper end of the likely range (globally 1.1 m under RCP8.5 by 2100) and from methods characterised by lower confidence such as from expert elicitation.

To sum:

1. Global sea levels continue to rise, with the rise itself accelerating (due to an acceleration in land-based ice sheet mass losses). This will continue, for beyond the lifespans of any now alive.

2. Beware of the eyecrometer. It will deceive you, if you allow it to.

SLR Components, from Cazenave et al 2018

Video: Arctic Sea Ice Minimum Volumes 1979-2019

Doug18698 at 12:47 PM on 15 November, 2019

Re: Why the Vikings came and then left Greenland. It is really quite simple. It was warm, there were very nice Birch forests, the glaciers were receding and everything was green. The land was good for farming, so you could raise cattle, goats and other livestock. Because of local warming you could ship goods back and forth from Europe. Then they got a cold snap that lasted a few hundred years. You can't farm if your land turns to permafrost. The sea started getting too much ice and too many storms. In a nutshell, climate change drove them out. It was the same thing that happened in Northern Canada. The camels and elephants (mastodons) could not find food anymore. Climate change wiped them out.

It's a 1500 year cycle

Philippe Chantreau at 11:29 AM on 9 November, 2019

The "obvious choice of a lunar origin" is discussed by Rahmstorf himself in the paper that you mentioned without referencing it, and apparently did not read because it does not support your hypothesis at all. From the conclusion section:

"The closest cycle known so far is a lunar cycle of 1,800 years [De Rop, 1971], which cannot be reconciled with the 1,470‐year pacing found in the Greenland data. The origin of this regular pacing thus remains a mystery."

Copied from: Rahmstorf (2003). Timing of abrupt climate change: A precise clock. Geophysical research Letters, 30 (10).

https://doi.org/10.1029/2003GL017115|

The Rahmstorf (2003) paper and others that I linked earlier explore why the weak forcing associated with this cycle fails to produce D.O. events in the Holocene. The climate effects are entirely owed to ocean circulation, especially salinity changes. There is other litterature suggesting that the cycle is still present but has not produced any noticeable climate effect since the last DO event. I am not impressed with how much you have explored the subject. This stuff is not hard to find.

CO2 was higher in the past

nyood at 04:18 AM on 7 November, 2019

@MA Rodger

(1a) "To present a value for CO2 forcing without providing evidential support is not axiomatic,
either in the sense of it being self-evident or (probably in the sense you intend) unquestioningly-evident.
The evidence can be presented should you so wish and, uncontroversially beyond-question, it is correct.

You yourself present @92 an unsupported evaluation of CO2 forcing, providing a maximum value which appears novel and controversial in the extreme.
You fail to present any evidential support which in the circumstance is turning this discussion into a pantomime.
Perhaps you could correct the untenable postion you create for yourself by providing that missing evidence."

(1a) The evidence that i imagine you would provide, will all result in the question: What is missing? This is manifested in the fact that you will get no exact value for CO2 sensitivity, despite known elemental spectral laws regarding infrared absorption. In other words: We are still estimating with 1,5°C - 4,5°C per doubling (?).

The theory that CO2 reaches a "saturation" already, is just the most likely aproach to me. However the forcings of HHE/LPC could be even that strong
that they shrink down all other factors making them neglectable, not "needing" any other explanation to temperature.

The major evidence i can deliver here is the fact that the so called saturation for each GHG is one of the known unkwons and that there are countless debates
on this issue, underlining how unsolved this whole matter is.

"(1b) Your confused statements regarding HHE/LPC appear to contrdict the geographical situation as commonly understood,
in that the "Land mass" Gondwawa sits static over the "Polar Circle" throughtout this period.
You need to consider how it is your LPC appears then disappears within this period when the contition you say causes LPC remains unchanging?"

(1b) I see no contradiction, in my former post i gave you the 2 links with the continental distribution, matching my theory.(Ordovizium, Silur)

I see what you are getting at though wih Schwanck slide 11: The pictures with the "paleo glacial reconstruction". They use a static continental distribution here. It is more likely that the continents were merging towards the hirnation. In a larger perspective the continents definetly move towards the pole, documented by the ordovician with the silurian as a whole. The ice needs to build up and the Boda event interrupted the glaciation process by reducing ice albedo.

"(2) Your cut-&-paste from the Schwark & Bauersachs slides appears particularly inept as support for your assertion "in fact it doubts CO2 as a driver."
If you, for instance, examine Slide 11 you will see your assertion is fundamentally contradicted."

What is contradicted here? Slide 11 shows the Boda event and its CO2 emissions, the CO2 does not matter to me, regarding temperature, the factors that matter are albedo reducing ashes and dust.

If you are refering to this sentence on page 11: "atmospheric emission of large amounts of CO2 and subsequent climate warming, and.."

Then i can only tell you that Schwarck et.al are using the neglectable CO2 sensitivity axiomata here. The reason why the Katian doubts ´CO2 as a driver´ is because it marks, with all other epoches preceeding the LPC event, the time where CO2 fails to work as assumed. Where should it show its significant forcing if not here?

"(3) Here you really do dip into uncomprehensibility. Do note that the Schwark & Bauersachs slides do not ever say CO2
dropped to present atmospheric levels 400-odd million years ago.
The statement you misread from Slide 23 says purely that CO2 varied "between 8-16 x PAL and near PAL."
The value 1500ppm can be taken from their Slide 11."

(3) Well, it does not matter to me, if you want it can be 1500ppm, i would not consider that close to PAL though. PAL would just makes sense to me since the ordovician

is compareable to all other LPC events.

Near Pal makes sense to me because it would reach common glacial CO2 levels. I have not enough knowledge of solubility.

Near Pal is enough for me to support the theory when it comes to: All equilibrium events and the transitions inbetween happen in the same fashion, despite varying CO levels.

"(4) If it is not land at the polar circle that creates your LPC condition; if it is ice-covered land,
you do then reqire to explain the forcing that allows the growth/shrinkage of that ice.
And in doing so, your theory now lacking the tectonic element, do consider that you are now describing a climate feedback not a climate forcing."

The factor that you are missing here is indeed a fundamental one. It is the fact that snow will not accumulate ice sheets on the sea.
The double proof for this is the arctic sea, with Greenland within the polar circle.

In fact with your misunderstanding here it makes me wonder if continental drift as a time dependet factor is included in the prognostications and not only be representd by the, in itself correctly implemented, ice albedo.

In other words:Fundamently excluding a long term factor of warming.

CO2 was higher in the past

Eclectic at 13:55 PM on 2 November, 2019

Nyood @85 , thank you for that comment: <"The only thing that will cause earth to leave the glacial period of the cenozoic is when Antarctica will move away from the south pole once again.">

I think it is not controversial that Earth will remain in an ice age for a very long time (ice age defined as Earth having substantial ice at one or both poles).

Even during the warm Eemian period, there was polar ice in the Scandinavian region (at least) plus the huge amount of land ice on the Antarctic continent.

A small rise in temperature (from today's) might fully melt Greenland ~ but that would likely take >1000 years. Still, most of the East Antarctica ice sheet will survive.

There are two scenarios where Antarctic ice will disappear:- (A) the very long term (many millions of years) as the solar output continues its gradual increase, and (B) an unexpected Large Igneous Province eruption of CO2, such as the Siberian or Deccan events. In either of these circumstances, the South Polar ice would disappear, even if Antarctica did not move from its present polar position.

The present day crisis involves the small-magnitude warming which will displace around 200 millon people as sea level rise approaches 1 metre [Kulp & Strauss, 2019]. And probably a much greater size of refugee problem, coming from storm surge, land salination, and other agricultural adverse effects (including low-humidity and high-humidity heat waves].

All this, within the lifetime of children born in 2019.

CO2 was higher in the past

nyood at 05:33 AM on 2 November, 2019

According to this recent study we have a way more accurate view on this issue now:

Schwark2019

In the Hirnation Event Summary:

"Massive perturbations of the atmospheric and hydrosphericcarbon cycle occurred with CO2concentration varying between 8-16 x PAL and near PAL over short periods of time." PAL means Present Atmospheric Level.

This is quite remarkable, it tells us that a glaciation is capable to absorb even CO2 ammounts of 6000ppm. It does not matter how high CO2 Levels are, a glaciation will happen when the following event occurs:

Sufficent Landmasses within the Polar Circles (LPC).

Going through all time periods, we can show how decisive landmasses at the polar circles are. Note that the polar circles represent a very narrow area at the north and south borders on these pictures. Greenland todayis a good example as it forms the only northern ice shield, mainly being within the arctic circle, while edging Canada and Russia are not inland iced.

Cambrian warm period, Landmasses in the Polar Circles (LPC): 0%-10%

Cambrian

Ordovician hirnantion glacial event antarctic LPC 100%:

HirnantionEvent

Silurian cold LPC antarctica 90%:

Silur

Devonian warming LPC 10% - 40% :

Devon

Carboniferus glaciation, Continents drop back to the south pole antarctic LPC: 90%-100%

Karbon

Permian Cold with late permian transition towards mesozoic Pangea arctic LPC 80% - 100%:

Perm

Triassic warming, antarctic PLC 10%-20%, arctic PLC 70% to 90%. only Southern PLC decisive? Arctic inland ice forming reversed with the jurassic? Triassic north pole contradicton.

Trias

Jurassic, Landmasses moved away from the arctic cycle. arctic LPC 10%-20%. antarctic LPC 5%-10%.

Jura

Cretateous, sea level rise noticeable, deglaciation at its maximum, transition to upcoming glacial period, Antarctica moving south. Antarctic LPC 80%-100%:

Kreide

Today, Cenozoic glacial period Antarctica resting at the pole once again. Greenland LPC 10% -20%, Antarctica 90%-100% LPC.

With an Ockham attempt i want to make 3 main arguments on why CO2 is not needed and not likely to play any thermal role at all:

1.Faint Sun Paradox,Snowball Earth and the Hot House Equilibrium.

The faint sun paradox is not a paradox. It is another evidence of how strong the terrestial force Ice Albedo is and therefore again the continental distribution.

Even with a 25% lesser sun, Oceans occur,hence the term "paradox".While precambrian snowball effects due to a supercontinent at the south pole, demonstrate the lesser sun effect.

The so called paradox underlines the trumendos forcings of Albedo and it describes the fundamental drive towards a hot house equilibrium whenever the poles are uncovered by land.

This Basic heating Trend that is strong enough to even compensate the faint sun paradox puts CO2 further away from having any thermal influence. This basic heat trend is documented by all the terminations of glacial epoches and even more so in the precambrian, with a barrier where no more heating seems possible.

So we keep in mind that we have a Glacial period during the ordovician to the early silurian, with Co2 levels around up to 6000ppm.

2. Carboniferous CO2 Levels

The carboniferous marks the point where the flora takes an increased influence on CO2 levels.

T°Co2overview

The late devonian till the middle carboniferus show how CO2 is absorbed while temperatur takes ~90 mio years to "follow".The reason temperature goes down is as usual, the continental drift towards the south pole.

What we eventualy see is a double decline in CO2.

The jurassic-cretaceous meeting of CO2 and temperature speaks for itself.

3. Today,GISS and an estimated CO2 sensitivity of 1,5°C

The uncertenty itself on the CO2 sensitivity after 30 years of research tells us per se that the science is not settled. IPCC on a global warming of <ahref=https://www.ipcc.ch/sr15/chapter/chapter-1/>1,5°C

"Past emissions alone are unlikely to raise global-mean temperature to 1.5°C above pre-industrial levels (medium confidence)"

"1.5°C emission pathways are defined as those that, given current knowledge of the climate response, provide a one- in-two to two-in-three chance of warming either remaining below 1.5°C

or returning to 1.5°C by around 2100 following an overshoot."

GISS actualy does show us a trend towards 1°-1,5°C ~2100 a.d. It is the natural interglacial trend. There is no evidence that our warming period is unique in its rate of warming compared to past medieval epoches

or to the past 11 Interglacials in our ice cores

The lowest model called the "russian model"

What is with Planck and Bolltzmann? my guess is Lüdeckepage19
and others are right, the saturation is already reached at PAL with 1°C

Since the Ordovian showed how much CO2 can be absorb in the oceans, acifidication of the ocean due to human emissions might be the bigger threat. Even though most of the CO2 was embeded in limestone, hence the CO2 "starvation".

How the Greenland ice sheet fared in 2019

MA Rodger at 21:27 PM on 16 October, 2019

Sequoia512 @8,

I think your numbers are a little out.

Over the last couple of decades, Greenland has been indeed losing somewhere in the order of a billion tonnes of ice a day but that is a net figure. The gross figure for ice loss (ie ignoring the gain from snowfall) is about five-times higher.

Your 100,000 years to melt half of the Greenland ice sheet at a rate of 1Gt/day would put the size of the ice sheet at 73,000,000 Gt. The ice sheet is considerably smaller at 2,850,000 Gt.

You ask why the Eemian was so hot? There is an SkS post addrssing that very subject here. The peak of the Eemian is reckoned to have had a "global mean annual surface temperatures ... warmer than pre-industrial by about 1° to 2°C." So today's global temperatures are not greatly different, and of course we are still warming. The last ice age did follow from the Eemian interglacial but that did require high-latitude Northern temperatures to drop from the peak Eemian, while we are going the other way so not any chance of an ice age arriving wiht AGW running as it does.

The thorium reactors are an interesting concept. Yet, while there are many projects around the world investigating the technology (including the Norwegian Thor project you mention), it has severe technological hurdles to clear. Note the link on that Thor webpage that says:-

Put simply, thorium-based reactors are still not economically viable for the most part. ... The result is, that at least for now, thorium reactors are unlikely to gain the upper hand over uranium oxide reactors. It’s possible that thorium reactors could become more dominant in the future, but a lot of work will have to be done to get to that point.

Video: Arctic Sea Ice Minimum Volumes 1979-2019

Eclectic at 20:52 PM on 16 October, 2019

Snoopy @2 ,

Antarctic ice loss has averaged about 13 cubic kilometers per year since 2001 , but has accelerated in the past 10 years. (Still quite small ~ under 10% of the ice loss from Greenland.)

Source: Rignot et al., 2019 (Proceedings of National Academy of Sciences)

How the Greenland ice sheet fared in 2019

Sequoia512 at 15:48 PM on 16 October, 2019

Nobody denies that the temperatures have increased since the Little Ice Age, thank god. However I feel you are a little overboard. Even if the Greenland ice sheet lost 1 billion tons a day everyday. Then never got snow again it would take over 100000 years to melt half the sheet. we will be back in full glaciation long before then. It was much warmer in the Emian interglacial and glaciation returned. Which brings up a point why was the Emian so hot?

Want to get climate change under control look to Thor. It is a Thorium test reactor in Norway. It uses thorium. Mox pellet rods in a conventional light water reactor. They are working on using depleted uranium as the neutron source to make Thorium fizz. This would use up most of our nuclear waste within 100 years. Quit killing birds with windmills. Also solar panels are highly toxic to decommission.

Greenland was warmer in 1940

Daniel Bailey at 09:00 AM on 14 October, 2019

It's much warmer now in Greenland than it was during the 1930's.

Greenland temps

To Embiggen

Let's look at that comparison graphically:

Antarctica is not part of the topic of this post.

For the interested reader, more info on Greenland historical temperatures are here.

It's cooling

MA Rodger at 03:09 AM on 14 October, 2019

richieb1234 @306,

The GISP2 ice core temperature record is Greenland temperature not global temperature. High Northern latitudes will have cooled more than global averages since the Holocene Climate Optimum (5,000 years ago). As a result, a reconstructed Greenland temperature would show today's Greenland temperatures still below those of the Holocene Climate Optimum.

The GISP2 data is often recycled by denialists (the graph below is from your link) suggesting the final data point represents today when it is actually 95 years before 1950 = 1855. CarbonBrief have a recent factcheck of the GISP2 data's misuse by denialists, along with a Greenland temperature reconstruction from multiple ice cores and brought up-to-date with modern instrument data, the today's temperatures being Berkeley Earth 20-year averages to 2013.

GIPS2 temperature

Your link also features the infamous IPCC FAR Fig 7.1c saying "it has become so 'inconvenient' they haven't mentioned it since & some scientists have tried to eliminate it." Again FAR Fig 7.1c has been much misused by denialists. Yet it was always a “schematic diagram of global temperature variations” with the “dotted line nominally represents conditions near the beginning of the twentieth century.” If anybody reads the text of IPCC FAR, it would also indicate plainly just how schematic Fig 7.1c was. Additionally, if Fig 7.1c were meant to be an accurate global temperature record, the 0.15 deg C temperature increase shown for 1900-50 would be a bit of a clue.

IPCC FAR Fig 7.1c

How the Greenland ice sheet fared in 2019

sgbotsford at 00:57 AM on 11 October, 2019

@william In #6:

You could also get increased snow too however. Some years ago, there was a pre-computer model of ice age triggering that was based on an open arctic ocean.

* Increased evaporation led to increased snow fall on surrounding land.

* Ungava penninsula has later springs and earlier falls.

* Increased albedo makes Ungava area cooler.

* Two randomly cooler summers in a row result in not all the snow melting.

* Because ground is pre chilled, snowfall accumulates faster.

* Cold air moving from the snowfield to surrounding area prepares that area for snow pack.

At the time they figured a permanent snowfield could advance at about 200 km per year.

No idea if this notion is still credible.

But: An arctic ocean will evaporate whenever it's open — slower winter, as I assume at least pan ice will form. But if the arctic is open while greenland is still 2 miles thick (and high) then soggy arctic air will cool and drop lots of snow.

If the latent heat comes from the formation of dew/frost, then your figures are correct. But it may form in the air, which means it's heat that ends up being radiated to space, no? If it comes down as snow, it melts nothing. If it comes down as rain, it melts some ice depending on the rain temperature.

How the Greenland ice sheet fared in 2019

One Planet Only Forever at 02:31 AM on 8 October, 2019

Another detailed presentation that is likely to have cherry-picking applied by climate science deniers and delayers.

The reported Surface Mass Balance is all they need to, want to, see and hear about. It indicates that Greenland ice is increasing, as long as the fuller story is never sought out.

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