Comments 1 to 22:

1. wayne19608 at 01:26 AM on 14 November, 2022

   how can there be any carbon budget left if we are at 1.2C already and have to subtract the negative aerosol forcing and deal with the time lag of 30 yrs?

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2. Bob Loblaw at 02:40 AM on 14 November, 2022

   Wayne:

   The opening section of the post gives a link to a Carbon Brief article that discusses this. (Well, to pick a nit, it links to it three times...)

   Perhaps you could look at it and tell us what you disagree with?

   They considered the following. The first three items would seem to address your concerns.

   • The estimate of global warming up to the present day;
   • The assumed future warming from emissions of non-CO2 forcings such as methane and black carbon and the reduction of cooling sulphate emissions;
   • The amount of warming still in the pipeline once emissions are brought back to zero;
   • The ratio between cumulative CO2 emissions and global warming (also known as the transient climate response to cumulative carbon emissions, or “TCRE”); and
   • The extra emissions from Earth system processes or feedbacks that are typically not included in the models used to make these estimates, such as thawing permafrost.
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3. wayne19608 at 04:00 AM on 14 November, 2022

   Thanks Bob I read the article but quite frankly I cant follow the logic that sees us limiting warming to another 0.3C

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4. nigelj at 05:33 AM on 14 November, 2022

   Wayne @3

   "Thanks Bob I read the article but quite frankly I cant follow the logic that sees us limiting warming to another 0.3C"

   The logic was spelled out pretty clearly: "This means that if we start reducing emissions steeply now and by the time we reach net-zero levels we have not emitted more than 580GtCO2, our best scientific understanding tells us have we expect a one-in-two chance that warming would be kept to 1.5C. "

   Doing it will be another thing. Challenging would be an understatement.

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5. wayne19608 at 05:43 AM on 14 November, 2022

   Nigelj I just cant reconcile those numbers with a 1.2C increase over 70ppm up to 1990 and another 70ppm in the last 30 years is going to somehow be under 0.3C and this is without further emissions or the removal of negative forcings with reduced natural capital to fall back on. I need help to square that circle

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6. Bob Loblaw at 07:08 AM on 14 November, 2022

   Wayne: "...I cant follow the logic..."

   Well, that's a convincing argument....not. You really are not giving a critique of the article, other than an argument from incredulity. How am I supposed to discuss that with you?

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7. One Planet Only Forever at 07:09 AM on 14 November, 2022

   wayne,

   Please restate your concern more clearly, with the following in mind.

   Regarding how much warmer than pre-industrial things currently are:

   I have read the following Nature news report from August 2021 "IPCC climate report: Earth is warmer than it’s been in 125,000 years". It includes the following:

   "Earth’s global surface temperature has increased by around 1.1 °C compared with the average in 1850–1900 ..." (based on IPCC reporting).

   I see other items stating that the average for January to October 2020 indicated a likely annual average of 1.2 C warmer. But that is just one year, and likely a peak year. Reviewing the Global averages in the NASA/GISS data set the average for 2021 was about 0.2 C cooler than 2020. And 2022 appears on track to be about 0.1 C cooler than 2020.

   Regarding the challenge of limiting future impacts to the amount that limits warming to 1.5 C:

   As nigelj pointed out, the evaluation states the required reduction. It does not declare it will be achieved. It is a warning that without a significant correction of behaviour by the highest consuming and impacting portion of the global population.

   It is undeniable that the lack of responsible adaptation by the highest impacting portion of the population through the past 30 years, failing to lead the development of sustainable ways of living, has developed a massive problem that the 'highest consuming and harmfully impacting' portion of the population continue to resist helping to limit.

   Admittedly, the required adaption to reduced energy consumption in parallel with a transition to renewable more expensive energy systems is not 'advantageous' to those who developed perceptions of superiority based on more harmful consumption. The adaptation to the higher costs of the less harmful alternatives in 1990 should have been paid for, especially by those who were wealthier. The parallel adaptation to reduction of energy use would have off-set the higher energy costs, reducing the total cost of the required adaptation.

   Understandably, the failure of responsible adaptation leadership through the past 30 years has created the far more dramatic required 'adaptation' today. And undeniably, the currently more fortunate people who benefited most from continued, and increasing, fossil fuel use through the past 30 years should be facing the 'greatest required amount of adaptation' as well as the costs of 'loss and damage' resulting from their lack of 'responsible leading by example'.

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8. wayne19608 at 07:23 AM on 14 November, 2022

   Bob are we saying that as CO2 concentration goes up its influence on temperature decreases?

   One planet are we not currently in the midst of an extended la nina that we can expect to sooner rather than later switch to an el nino with concurrent increases in temperature?

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9. Bob Loblaw at 07:45 AM on 14 November, 2022

   Wayne @8:

   I have no idea what point you are trying to make.

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10. One Planet Only Forever at 09:27 AM on 14 November, 2022

    wayne,

    The past few years have been 'weak la nina'. The history of ENSO can be seen in the NOAA ONI values.

    Though the ONI is not the only factor determining ENSO events (there is also the SOI and other factors), the ONI values indicate that 2019 was the end of a weak el nino event. And that el nino condition may have been reflected in the higher 2020 value (note that 2020 was a little warmer than 2019). The weak la nina condition started in 2020 and continues through today. And ENSO isn't the only 'variable influence' causig temporary global average values to peak above or below the 'long term average line'.

    The point remains that the 1.2 C warmer global average of 2020 does not represent the value of average warming as shown by 2021 and 2022.

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11. wayne19608 at 10:39 AM on 14 November, 2022

    Bob @9 Im referring to 70ppm resulting in an increase of 1.2C(or1.1C following One Planet) versus the following 70 ppm increase being limited to 0.3C(or0.4C). Not where the misunderstanding is coming from so not sure how to fix it

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12. Bob Loblaw at 11:11 AM on 14 November, 2022

    Wayne @11:

    I have no idea where you get 70ppm leading to 1.2C warming. I have no idea what the "following 70 ppm" refers to.

    Here are a few hints that might help:

    • Give a specific reference to the article you are talking about. In your first comment, I had to guess that it was the Carbon Brief article.
    • Give specific quotes or descriptions of the part of the article you want to discuss.
    • Give an explicit indication, in your own words, of the part that you either do not understand or disagree with.
    • Give an indication of what your current understanding is (or lack thereof), and explain how it differs from the article you are looking at.
    • Pose clear questions, based on the above.

    Without this information, you are leaving the readers guessing. The SkS web site is rather old in design, and has not yet implemented a "read commenter's mind" function. (We don't expect to have such a function any time soon.)

    Leaving things vague is inviting misunderstanding. Brevity is not your friend.

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13. wayne19608 at 11:44 AM on 14 November, 2022

    Bob @ 11

    280 ppm CO2 plus 70 ppm CO2 gives you 350 ppm CO2 which covers the time period from pre industrial to 1990. 350 ppm CO2 plus 70 ppm CO2 covers the period from 1990 to 2020ish which nicely includes the 30 year time lag. That first 70 ppm of CO2 has resulted in a 1.2C (or 1.1C) increase in temperature but the next 70 ppm CO2 from 1990 to 2020 is suppossed to be limited to a 1 in 2 chance of less than 0.3C(or 0.4C)?

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14. Bob Loblaw at 12:01 PM on 14 November, 2022

    Well, that's a little better, Wayne, but you are still leaving out important details.

    Skeptical Science has a trend calculator, available in the Resources menu.

    https://skepticalscience.com/trend.php

    Regardless of which global temperature trend I choose there, I see no more than 0.6C warming from 1900 to 1990 (choosing "1900" to guess at your "pre-industrial" term).

    So let's try this one more time:

    • Give a specific reference to where you are getting CO2 concentrations from.
    • Give a specific reference to the source of the temperature data that you are using.
    • Give specific dates, not vague terms such as "pre-industrial".

    Your 1990 CO2 values seem reasonable, based on figure 2 of this SkS post.

    

     

    Your 1990 temperature increase value seems wildly out of whack. (The anomalies in the above graph are not referenced to 1900. The trend calculator consistently shows different data sets giving about -0.4C in 1900, making 1990 about 0.6C warmer.)

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15. wayne19608 at 12:07 PM on 14 November, 2022

    Bob thats because the temperature isnt from 1990 its from 2020 otherwise you arent taking into account the lag in carbon cycling

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16. MA Rodger at 18:36 PM on 14 November, 2022

    wayne @1,

    I roll back to your initial question as there has been a lot of stuff inbetween which hasn't got you anywhere.

    In terms of carbon budget, the most simplistic calculation (this ignoring any consideration of aerosols etc) would be that emissions halve by 2030 at which point atmospheric CO2 will have peaked due to the natural draw-down into the biosphere/oceans. And with CO2 the main driver of AGW and AGW running at +0.25ºC/decade, the +1.5ºC limit is not impossible.

    But things aren't that simple.

    The climate scenario SSP1-1.9 adds in the other drivers of AGW and that does show that AGW would peak close to the +1.5ºC limit. In terms of CO2, note that SSP1-1.9 includes negative emissions post-2050 which will draw-down and sequester all the CO2 we emitted post-2007.

    The aerosols do pose a problem for scenarios like SSP1-1.9 as their forcing is not well quantified but they are factored in.

    So SSP1-1.9 shows we do have a chance of having a chance at keeping AGW below +1.5ºC but as was said at COP27, that chance of a chance is on life support and the life support machines are "rattling."

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17. Daniel Bailey at 23:22 PM on 14 November, 2022

    "how can there be any carbon budget left if we are at 1.2C already and have to subtract the negative aerosol forcing and deal with the time lag of 30 yrs?"

    Wayne at #1 atop this thread refers to the archaic and outdated idea of a multidecadal lag between cause and effect of our CO2 emissions (originally discussed here at Skeptical Science).  Much research shows otherwise (that peak warming from our CO2 emissions is reached in less than a decade), so much so that it is the consensus position of the AR5 and the AR6.  A better summary discussion of that concept can be found in this post here at Skeptical Science.  The semimythical multidecadal "lag" is sometimes used as a ruse to delay taking needed action to transition away from fossil fuels.

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18. Bob Loblaw at 23:50 PM on 14 November, 2022

    Wayne @ 15:

    No, the 2020 temperature is not due to the 1990 CO2 level plus lag. The 2020 temperature is due to the 1990 CO2 level, plus lag, plus the short-term effects of every year of CO2 increase since 1990. It includes:

    • 29 years of lag from the 1991 CO2 level...
    • 28 years of lag from the 1992 CO2 level...
    • 27 years of lag from the 1993 CO2 level...
    • 26 years of lag from the 1994 CO2 level...
    • etc.

    You clearly have not thought this out.

    ..and we could have gotten here a lot more quickly if you had been explicit about how you arrived at your viewpoint from the beginning, instead of making me ask a bunch of questions trying to find out how you came up with your incorrect interpretation.

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19. Bob Loblaw at 00:29 AM on 15 November, 2022

    Further to Daniel's post #17, there is also a discussion of Ocean Time Lags in the SkS analogy series, written by Evan.

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20. One Planet Only Forever at 04:11 AM on 15 November, 2022

    This discussion has been helpful. It has clarified the understanding, still being improved, regarding the delay of global average temperature increase relative to an increased CO2 impact.

    That should help correct/improve the misunderstanding that wayne started with.

    It also presents an example of 'helpful misunderstanding' vs 'harmful misunderstanding'. Misunderstanding can be helpful if the resulting actions reduce harm done, but for a reason that is not the best understanding. However, even 'helpful' misunderstandings should be improved, even if the result is less anxiety to be less harmful. The challenge is doing that in ways that do not make the potential for harm appear to be less of a concern, resulting in people unjustly benefiting from more harm being done.

    The 'helpful' potential of wayne's misunderstanding would be wayne believing that there is an immediate need for:

    • the biggest most-harmful consumers to end their over-consumption of energy.
    • richer people to pay the required extra costs to use the least harmful renewable energy.
    • richer people also need to help the less fortunate be less harmful as they develop to live basic decent lives (live like the examples set by the supposedly more advanced humans).

    That 'helpful' misunderstanding should be tempered by learning that the need for change is urgent (an emergency ... not yet a total disaster). The required change does not have to happen immediately. But the required adaptations remain the same, just able to be done through the next few decades with more adaptation happening earlier.

    A 'harmful' misunderstanding would be that 'it is already too late so why bother' or 'the required corrections won't happen so there is no need for people to try to be less harmful'. 'Harmful' misunderstanding could lead a person to vote for leaders who harmfully argue against the aggressive actions required to achieve the understood 'required adaptations by the richer, more harmful consumers, and more harmful pursuers of profit'.

    Less harm done is better. So it is never too late to improve awareness and understanding of what is harmful and the ways to be less harmful and more helpful. But the longer the people who don't want to be less harmful and more helpful 'have the freedom' to not 'face the required adaptation consequences' the more severe the 'required adaptation consequences should be for them'.

    The popularity of 'harmful misunderstanding' has set-up this harmful fossil fuel use development to not end well.

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21. Bob Loblaw at 05:26 AM on 15 November, 2022

    To illustrate my comment at 18, about time lags, let's consider a very simple case, where we can treat the earth as a zero-dimensional point with an instantaneous addition of CO2 to cause a 4 W/m² imbalance in the global radiation balance. (This is a number typically associated with a doubling of CO2.)

    This imbalance represents a positive energy input that will warm the system. It will not warm it instantaneously, though - we need to account for the heat capacity. (Yes, a point can have a heat capacity, just like calculus tells us a line can have a slope at a point.)

    We will consider three heat capacities:

    1. Just the atmosphere.
    2. Oceans, but just to a depth of 60m (the mixed ocean layer)
    3. Oceans to a depth of 2000m.

    The low heat capacity of the atmosphere would allow rapid heating. Each addition of ocean mass slows the heating.

    This is what we'd see as heating rates for those three scenarios:

    

    We see that if the atmosphere was the only thing heating, we'd be done in less than a year. We see the system reaching equilibrium, with a warming of about 3C. (I have tuned the model's albedo and water vapour feedbacks to get that 3C result.)

    Adding the ocean mixed layer slows things down quite a bit, but we still reach equilibrium in roughly 10,000 days (about 30 years). Adding deep oceans really slows things down - we're still far from equilibrium at the end of the graph.

    As the system heats, the radiative imbalance decreases. Those values are in the following graph. Atmosphere-only equilibrates quickly; ocean versions more slowly.

    

     

    The shape and relative position of the three lines in each graph would not change if you did a 2W/m² initial imbalance, or changed the model sensitivity - it depends on the heat capacity used.

    Of course, the real world is more complex. You are not heating a single mass, and the atmosphere, land and oceans have transport between them (and transport to different parts within them). You can't include that in a zero-D model, though.

    More importantly, we are not dealing with an instantaneous increase in CO2. It is gradually increasing. We can add those things sequentially over time, though:

    • In year one, we add some CO2. The atmosphere reacts quickly, but the oceans react slowly. We still have some warming waiting "in the system".
    • In year 2, we add more CO2. Again, the atmosphere reacts quickly, the oceans more slowly - and we also have the heating still going on from year one's "ocean lag".
    • In year 3, we get another increase in CO2. Another rapid atmosphere warming, and some slower ocean arming from this year's CO2, plus a one-year lag form last year's ocean heating, and a two-year-lag from the first year's ocean heating.
    • ...and so on.

    What you can't do is assume that the temperature rise after 30 years is just the year one CO2 value after a 30-year ocean lag. CO2 has been increasing since then, with 29, 28, 27, 26 etc. years of heating since it was added.

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22. Bob Loblaw at 12:54 PM on 15 November, 2022

    Now, to expand a little on that zero-d model from comment # 21. I mentioned that a gradual increase in radiative forcing wlil be different from an instananeous step change of 4W/m². We can look at that using the same model. We will do three new simulations, to add to the Ocean Mixed Layer one from comment #21, making four simulations:

    1. The original instantaneous 4 W/m² step change.
    2. A scenario where we gradually increase the radiative forcing over 2500 days.
    3. A scenario where we increase it over 5000 days
    4. A scenario where we increase it over 10000 days

    In each case, we keep the same heat capacity (ocean 60m depth - middle line from comment #21). We also keep the same final radiative forcing: 4 W/m2 at the end of the "ramping up" period (1, 2500, 5000, or 10000 days).

    Here is the temperature evolution:

    

     

    ...and here is the radiative imbalance:

    

     

    Note that the temperature evolution over the 10,000 day period is quite different if we spread the forcing over a longer period. In the fourth line, when full radiative forcing is not reached until day 10,000, we still have a ways to go before reaching equilibrium. The system has responded fully to the forcing that was added 30 years ago, but not to the recent forcing.

    You will note that the imbalance graph only reaches 4W/m² for the 1-day (instantaneious) step change. That is the difference between the radiative forcing and the radiative imbalance - they are not the same thing.

    • The forcing is an input, and is always expressed relative to the pre-change conditions (day 0).
    • The imbalance is the net difference between the forcing and any adjustments in the outgoing radiation related to how the system has heated up. Since we do not reach 4W/m² forcing until day 2500 (or 5000, or 10000), the system has had a chance to adjust to the forcing that happened before that day.

    In the 5000-day ramp-up, we reach 4W/m² of forcing on day 5000, but the system has already achieved about 2.4W/m² of adjustment, leaving only 1.6 W/m2 imbalance.

    Again, the temperature evolution over time is different. You need to consider this when interpreting the temperature evolution with respect to time lags, forcing etc.

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