Comments 1 to 37:

1. Gilles at 18:13 PM on 15 April, 2011
   so as DM reminded us several times, a scientific theory cannot be proved, but it can be disproved-actually it *is* scientific only if it *can* be disproved. So in your opinion, what could disprove AGW theory ?
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   Moderator Response: [Dikran Marsupial] Trollometer reading: |========--|

   The IPCC WG1 report is full of falsifiable predictions, pick one. Additional hint, a theory about climate is unlikely to be falsified by an observation of weather; they are not the same thing. I'm glad to see you have got the idea of falsificationism at last though, and are talking about disproving rather proving theories. That at least is some progress.

2. Albatross at 00:45 AM on 16 April, 2011
   Nicely done John-- concise and to the point. Good idea to start of showing the rising temperatures. With that said, I'm sure that you have read Tamino's recent post on this. He demonstrated that the snow was moving northwards in the northeast USA, specifically the Mid-Atlantic states and New England. That trend shifted in the last two winters, but that is only two data points out of 30 or so that he looked at, and appears to be associated with the wild swings in AO possibly related to the loss of Arctic sea ice. What is really impressive is how quickly all that snow is melting come spring, and that the model simulations predicted this increase in boreal winter precipitation at mid and high latitudes. Anyhow, these events form part of an increasing trend in extreme rainfall events that has been emerging in recent decades as atmospheric water vapour content increases in response to the warming. And not to forget the two recent seminal nature papers .
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3. ahaynes at 08:00 AM on 16 April, 2011
   I haven't watched the video, text being faster, but - I hope it notes that (& distinguishes between) a) getting more snow with *local* warming, if winters were cold enough already; and b) getting more snow due to global warming that causes local cooling, if the Arctic "freezer door" gets stuck open. Where I live, this winter we've been getting lots of Arctic-air storms, so many more snowfalls than usual.
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4. dana1981 at 09:19 AM on 16 April, 2011
   Very nice job John and Matthew!
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5. Gilles at 18:51 PM on 16 April, 2011
   "The IPCC WG1 report is full of falsifiable predictions, pick one." Actually I have very hard time to find one. Seems rather that everything that doesn't match is called "weather", "noise", "internal variability" - but nowhere a definite answer of what is testing what. Note that the final conclusion that "it is very likely that the main contribution of the recent temperature rise is mainly anthropogenic " is not testable- since the "likelihood" cannot be checked in itself. And I'm sorry to disappoint you, but I've not waited for you before understanding what falsificationism means - I've probably needed less time to understand it that you need to understand me.
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   Moderator Response: [Dikran Marsupial] You are displaying your ignorance, yet again. The IPCC model projections give forecasts for the rise in temperature, all with increasing temperatures over the next century. The error bars on those projections (i.e. what is plausibly attributable to natural variability or "noise") exclude the possibility of temperatures falling (or even remaining approximately level) over the next century. So if the temperature falls over the next century, the theory is falsified.

   Lets make that more concrete, the "business as usual" scenario is A1F1, which involves rapid economic growth driven by exploitation of fossil fuels. The projection for A1F1 by 2100 is between 2 and 6 degrees of warming.

   

   So here is a directly falsifiable test: Follow A1F1, if temperatures in 2100 are lower than they are now, something the models clearly indicate is impossible, then the models and the underpinning theory must be wrong. Unless, of course there is a major change in natural forcings, for instance Yellowstone erupting, or the Earth being hit by an asteroid, which, but it would be idiotic to object to that sort of caveat!

   By the way, I pointed this particular IPCC projection out to you only yesterday, so you have no excuse for not being able to find a falsifiable projection in the IPCC report. I had already shown one to you!

6. batsvensson at 00:35 AM on 17 April, 2011
   Did any one propose, say, 10 years ago that snowing will increase when the climate warms up?
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7. JMurphy at 02:05 AM on 17 April, 2011
   bastsvensson, that was predicted back in the 1930s at least, albeit wrongly trying to explain a different topic : In 1937 [Sir George Clarke Simpson] suggested that, paradoxically, an increase of solar radiation might bring on an ice age. His reasoning was that a rise in the Sun's radiation would warm the equator more than the poles, evaporating more water from the tropics and increasing the rate of the general circulation of the atmosphere. This would bring more snowfall in the higher latitudes, snow that would accumulate into ice sheets. According to Lamb (1977), p. 661, the first to recognize that an ice-free Arctic Ocean would lead to more snow near the ocean (based on observations of 20th century warm years) and that this could lead to onset of glaciation was O.A. Drozdov; the work was not published at once, and Lamb cites a later publication, Drozdov (1966). Also from The Discovery of Global Warming
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8. JMurphy at 02:12 AM on 17 April, 2011
   Or how about this, more directly related, from 8 years ago : Early Warning Signs of Global Warming: Downpours, Heavy Snowfalls, and Flooding From UCSUSA
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9. les at 02:14 AM on 17 April, 2011
   7 - JMurphy every day an education! Replies like that are what SkS is (should be) all about.
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10. JMurphy at 02:32 AM on 17 April, 2011
    Or this, also from 8 years ago : Global Warming Means More Snow For Great Lakes Region From Science Daily And this from 10 years ago : Another point to note is that while continental-scale snow covered extent is expected to retreat in response to global warming, it is not so clear what other aspects of the snow cover may do. Increased precipitation may lead to increased snow accumulation in cold climate regions, while warming will be accompanied by increased frequencies of mixed precipitation and rain-on-snow events which have implications for snowmelt, snow depth and snow density. Documenting and understanding these characteristics requires monitoring with surface-based observations in addition to satellite data. Is Snow Cover Changing in Canada? It's not difficult to find...
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11. batsvensson at 03:59 AM on 17 April, 2011
    Hence, when temperature increase snowfall will increase around the polar region causing a greater reflective surface and possible off set any further increase in temperature which in turn may trigger and ice age. Is that correctly understood?
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12. JMurphy at 04:18 AM on 17 April, 2011
    batsvensson wrote : "Is that correctly understood?" Not by me, anyway. What led you to such understanding ?
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13. batsvensson at 06:09 AM on 17 April, 2011
    Global Warming Means More Snow For Great Lakes Region ScienceDaily (Nov. 6, 2003) — Global warming has had a surprising That is not a prediction JMurphy
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14. batsvensson at 06:10 AM on 17 April, 2011
    What led you to such understanding ? "In 1937 [Sir George Clarke Simpson] suggested that, paradoxically, an increase of solar radiation might bring on an ice age."
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15. JMurphy at 10:39 AM on 17 April, 2011
    batsvensson, firstly you should read more than the title and first line of anything, if you want to find out more information - such as the following paragraph from that link : “Recent increases in the water temperature of the Great Lakes are consistent with global warming,” said Burnett. “Such increases widen the gap between water temperature and air temperature – the ideal condition for snowfall.” I.E. increased temperature leads to increased snowfall. Secondly, you shouldn't rely on outdated ideas, especially since the site I linked to continues : It was no more nor less convincing than anyone else's ideas. At a time when scientists could not explain the observed general circulation of the atmosphere, not even the trade winds, theories about climate change could be little more than an amusement. I.E. things have moved on a bit since then. But you seem to have ignored the UCSUSA link...
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16. batsvensson at 19:37 PM on 17 April, 2011
    JMuphy, clearly your understanding of what constitutes a prediction is fundamentally different from mine but I see no point in discussing that issue any further here. My understanding is that global warming is attributed as cause for the recent increased snowfall. Assuming this understanding being correct, is there any other possible cause for this and if so what reason do we have to exclude those explanations as causes for the increased snowfall?
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    Moderator Response: [DB] Where I live (in the northern snow belts of the Great Lakes of North America) snowfall totals have been down significantly for the last several years. So increases are not necessarily global or even regional.
17. batsvensson at 19:46 PM on 17 April, 2011
    "But you seem to have ignored the UCSUSA link..." etc... You asked me what lead me to such understanding with out this I answer you assuming nothing. However you seams to have taken my answers as an opportunity to followed up with personal attacks on me. I would suggest you try keep to the subject instead and not discuss my person or knowledge base.
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18. batsvensson at 19:59 PM on 17 April, 2011
    JMurphy wrotes: "Secondly, you shouldn't rely on outdated ideas, especially since the site I linked to continues" Does this imply that you reject the idea that an extended snow cover will increase the heat flux out from the earth surface and cause global temperature to decrease or have I missed something here?
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19. JMurphy at 22:36 PM on 17 April, 2011
    batsvensson, I haven't a clue where you get the "personal attacks" belief from, but if that is what you see, it isn't what I intended. Is English your first language ? If not, perhaps that is where the difficulty is. Anyway, no personal attacks intended. But, with regard to your original question : Did any one propose, say, 10 years ago that snowing will increase when the climate warms up? I think you should have seen by now that the answer is 'Yes'. Yes ?
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20. les at 23:03 PM on 17 April, 2011
    18 - batsvensson regarding "extended snow cover will increase the heat flux out from the earth surface and cause global temperature to decrease" The onus is on you to show or find papers which show that this follows. To me, it's not obvious. Calculating the impact on "heat flux" - I guess, how much more or less energy is radiated / reflected - due to extra snow fall in the north needs some work. I know where I live (about 64°32'N) where it's snow covered almost 5 months a year, extra snow fall won't make much difference. On the one hand the ground is already mostly white; I'd guess the snow keeps the ground warm (white doesn't radiate as much as black). On the other hand, it's dark, the snow reflects very little sunlight - there is very little sun light to reflect! That's during the winter - at the 'margins'... will there be extra days of snow cover or fewer? etc. All has to be calculated. Other parts of the world would differ to here. Will there be substantial snow cover where there was none? Or longer snow cover? Will that reduce the rate of cooling? Or reflect more sunlight? You have to be able to estimate how much extra snow and the impact of that, if any. maybe someone's done some estimates, may you'd like to give it a try! ... certainly you cannot jump from "there will be more snow falling in the north" to "there'll be an ice-age"! Looking forward to seeing the fruits of your research.
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21. Gilles at 23:49 PM on 17 April, 2011
    DM :"So here is a directly falsifiable test: Follow A1F1, if temperatures in 2100 are lower than they are now," yes but the scenario is in itself not steerable - so what you propose is mainly a counterfactual test . Can't you propose a test valid for any scenario, and if possible, soon enough ? if you can't , it means that all AGW "theory" is still in a state of hypothesis ...
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22. Dikran Marsupial at 00:13 AM on 18 April, 2011
    Gilles@21 Firstly, it is steerable, all we have to do to see A1F1 is to carry on doing just what we are doing now. Secondly, for falsifiability, it doesn't have to be steerable (e.g. Eddington's corroboration of Einstein's theory of relativity, neither Einstein nor Eddington control the positions of stars or planets). Thirdly, it doesn't have to be A1F1, if temperatures fall over the next century by say a degree or more below the lower error bar of the most appropriate scenario, that would falsify AGW theory. As the models have been published, you could even in 2100 put the observed forcings into the model and AGW theory would be falsified if the observed rise in temperature was (say) a degree less than the lower error bar. It isn't hard to come up with a falsifiable test, of AGW, simply because it makes a lot of predictions.
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23. Gilles at 16:22 PM on 18 April, 2011
    so you mean that the falsifiable content of AGW theory is restricted to "the temperature will rise in the XXI century". I would buy it, since I do believe that CO2 is indeed a greenhouse gas and must contribute to some warming, and that generally it seems that even natural variability has ended a cold period in the XIX century and this is likely to last a little bit more. So it's more likely that temperature will increase that they would decrease anyway (even without CO2, I would think the same). Now this is a rather weak assertion, very far from "it will be a catastrophe for mankind and we must stop ASAP all use of FF to avoid it". Do you have any falsifiable test to support the latter assertion ?
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24. Dikran Marsupial at 17:04 PM on 18 April, 2011
    Giles@23 wrote "so you mean that the falsifiable content of AGW theory is restricted to "the temperature will rise in the XXI century" No Gilles, I didn't say any such thing, you know it, I know it and anyone reading this thread also knows it. I said the IPCC report is full of falsifiable predictions, that temperatures will rise is only one of them. I had been giving you the benefit of the doubt, but that is just blatant trolling and you should be ashamed of yourself.
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25. muoncounter at 01:20 AM on 23 April, 2011
    Interesting recent letter in Nature: Kaspi and Schneider 2011 Winter cold of eastern continental boundaries induced by warm ocean waters we show that this anomalous winter cold can result in part from westward radiation of large-scale atmospheric waves—nearly stationary Rossby waves—generated by heating of the atmosphere over warm ocean waters. ... Our results show that warm ocean waters contribute to the contrast in mid-latitude winter temperatures between eastern and western continental boundaries not only by warming western boundaries, but also by cooling eastern boundaries. Figure below: Surface temperature deviation averaged over northern hemisphere winter months and across 40 years. Credit Tapio Schneider Yohai Kaspi -- source A standing wave pattern with a wavelength the distance from Seattle to London?
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26. Bob Lacatena at 03:20 AM on 23 April, 2011
    25, muoncounter, Interesting!!! I notice, too, while over at Nature, that they have just launched Nature Climate Change (Vol 1, Issue 1, April, 2011). At $112 the subscription is a bit pricy (especially since it's not all encompassing, e.g. the article you posted is not there... I guess it's "weather"), but I'm considering it.
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27. Ken Lambert at 23:26 PM on 28 April, 2011
    Hey Sphaerica, Just think of the INCREASE in albedo for all that record area of snow white snow covering the NH areas for a few extra weeks. Could lead to an unnatural cooling.
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28. adelady at 23:30 PM on 28 April, 2011
    That'll only work, Ken, if the snow hangs around long enough to reflect any worthwhile input from the sun. A lot more snow/albedo at a time when there's very little radiation from the sun makes little to no difference. If we could find a way to make it stay on through spring and summer, then we'd be talking!
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29. batsvensson at 21:51 PM on 7 May, 2011
    @JMurphy: You wrote "batsvensson, I haven't a clue where you get the "personal attacks" belief from, but if that is what you see, it isn't what I intended. Is English your first language ? If not, perhaps that is where the difficulty is. Anyway, no personal attacks intended. " You claim that I had not read more than "the head lines" and also suggested that I lack proper knowledge. I am puzzled about how you possible can have any knowledge of this? To fence of my comment you then suggest I do not have proper understanding of English. These are all comment about my person and not the subject at hand or do you disagree with me on this?
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30. batsvensson at 21:54 PM on 7 May, 2011
    "Moderator Response: [DB] Where I live (in the northern snow belts of the Great Lakes of North America) snowfall totals have been down significantly for the last several years. So increases are not necessarily global or even regional." I do not see what the relevance if this comment is to what I wrote. And why is it made as a moderator response?
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31. batsvensson at 22:00 PM on 7 May, 2011
    Errata: "I do not see what relevance this comment has to what I wrote."
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32. Bob Lacatena at 23:36 PM on 7 May, 2011
    27, Ken,

    Just think of the INCREASE in albedo for all that record area of snow white snow covering the NH areas for a few extra weeks. Could lead to an unnatural cooling.

    Unlikely. First, extra snow on top of snow already there will not change albedo. Second, the snow exists primarily in the winter months when insolation is already low (much shorter days, low angle of incidence). Third, the extended snow cover could well be offset or even more than offset by earlier springs (i.e. it melts away sooner, and snow that was usually there at more northern latitudes also melts away sooner), or by later winters (i.e. what snow usually arrives does not accumulate on average until later in the winter). Fourth, snow that falls much further south doesn't last long, because temperatures there do not usually remain low for extended periods of time. Much of this snow won't last weeks, let alone into the spring. Certainly, I think it would make an interesting study, and a small negative feedback is possible. Without actual numbers and specifics I'd leave this in the "interesting" category... You can see the Winter (low insolation) versus early Spring (higher insolation and less snow cover, not more) using the Rutgers University Global Snow Lab. Compare November and March (less lower latitude snow) to December through February (more snow on top of snow, or snow reaching lower latitudes). ...but it's hardly going to reverse climate change, or have much impact on total climate sensitivity, which is founded on a lot more than a nit-picking accounting of every individual positive and negative feedback.
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33. Bob Lacatena at 23:41 PM on 7 May, 2011
    On snow extent, four more interesting graphics, among others, from the Rutgers U. Global Snow Lab: Spring NH Snow Extent Winter NH Snow Extent Eurasia Spring Snow Extent North America Spring Snow Extent
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34. JMurphy at 07:03 AM on 10 May, 2011
    batsvensson, this is getting ridiculous so I will just write this, if I may be allowed to post one final off-topic distraction : Your assertion was seemingly based on a quote from The Discovery of Global Warming, which I linked to to show a prediction that "snowing will increase when the climate warms up" - something you asked for. I.E. your assertion was seeming wrongly based on one line of one paragraph from that link - a paragraph that ended thus : At a time when scientists could not explain the observed general circulation of the atmosphere, not even the trade winds, theories about climate change could be little more than an amusement. Also, you used the title of another link I provided to suggest that it was "not a prediction", even though, beyond the title and within the body of the article, was this : Recent increases in the water temperature of the Great Lakes are consistent with global warming,” said Burnett. “Such increases widen the gap between water temperature and air temperature – the ideal condition for snowfall. I.E. increased snowfall was expected and confirmed. Perhaps the use of the informal pronoun 'you', rather than the more formal 'one' was a mistake, but, to return to the accusation you have made, that was why I suggested reading more than the title and/or first line of anything. However, nowhere have I suggested that you "lacked proper knowledge" - as far as I can see. That would explain that particular puzzlement. Nor did I suggest that you did "not have proper understanding of English" - I suggested that, if English was your second language (which I don't know; which is why I asked), that might explain why my words looked different to you than they did to me; or why the way I used the language (perhaps more playfully than warranted) could be misinterpreted or (mis)construed. In conclusion : yes, I disagree with you on this.
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35. seeker25801 at 01:27 AM on 1 June, 2011
    Global warming: maybe. Man-made global warming: nah. I just wish both sides would tell the full story. Our climate is "dynamic". Ever-changing. We're coming OUT of a global cooling period so of course it's going to get warmer. And weather is NOT climate.
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36. JMurphy at 02:30 AM on 1 June, 2011
    seeker25801, to find out how you have come to the conclusions you state, how about answering a few questions ? 1) Why do you say "maybe" to global warming ? 2) Why do you say "nah" to Man-made global warming ? 3) What are the two sides ? 4) How does the climate being "'dynamic'" and "ever- changing" prove that man is not affecting the climate ? 5) When did the "global cooling period" start, when do you think it will end, and what forces are causing us to come out of it ? Depending on your answers, discussion can be taken to other threads where your claims may already have been discussed.
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37. Tom Curtis at 14:12 PM on 1 June, 2011
    seeker25801 @35, according to the people most in the know, global warming is almost certainly occurring, and it is very highly probable that human activities are the major cause. Whether you think they are telling the full story or not, it is certain they know the full story better than anybody else on Earth. So the question you should be asking, seeing you so strongly disagree with them, is what is it that they know that you do not? If you read the arguments on this site, you will find out, for contrary to your insinuation, the climate scientists, and this site do tell the full story, so far as it is known.
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