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Comments 59951 to 60000:

59951. R. Gates at 14:34 PM on 19 April 2012
       Global Surface Warming Since 1995
       Wow, another excellent post. Really too bad most skeptics won't ever read this, and then of those who do, maybe 1 in 5 will grasp it.
59952. skywatcher at 13:59 PM on 19 April 2012
       Models are unreliable
       Perhaps, Manny, if these are indeed "claims of climate theory", as you propose, you could furnish us with the references in the peer-reviewed literature where either of these claims are made. I contend that you can't do this, as the first claim is made by a politician in a film, and the second is a personal opinion by (James) Hansen in a youTube video. See if you can find either statement in the published literature or in the IPCC reports. What you will find in the published literature: extensive discussions of empirical evidence documenting the causes and impacts of climate change, with uncertainties attached; discussions, with evidence and uncertainty, of how sensitive our climate is to change (e.g. 2C-4.5C warming per doubling CO2); discussion of model representations of the climate system, with assessment of their strong and weak points. Models validate the core propositions of our theory of climate very well. Seasonal weather forecasts are an irrelevant distraction, being both notoriously unreliable and bearing precious little in common with climate modelling. I wonder why 'skeptics' would wish to conflate the two?
59953. nautilus_mr at 13:58 PM on 19 April 2012
       Cliff Ollier: Swimming In A Sea of Misinformation
       Just a quick question regarding figure 7, for those with greater technical expertise than myself: I don't get the pattern of sea level rise -why does it not rise uniformly, and why is it particularly high in the Australasian region?
59954. Manny at 13:44 PM on 19 April 2012
       Models are unreliable
       Scaddenp brought me here to answer his question, so here I am. I said that extraordinary claims require extraordinary evidence. Sccadenp asks "Sorry, what is extraordinary about the claims of climate theory?" Here are two examples: "And that is what is at stake: our ability to live on planet Earth, to have a future as a civilization." Al Gore, An Inconvenient Truth. "On the long run, if this [increase in greenhouse gases] continues for centuries, that's it for all the species on this planet." John Hansen, The Runaway Greenhouse Effect (YouTube video) I call these claims extraordinary and I expect an extraordinary amount of model validation before I accept the consequences, which are also extraordinary. And, for hearing too many failed season-long forecasts from our Canadian chief meteorologist, I do not believe a minute that we understand all there is to understand about the physics of climate. Read this for fun: Balmy winter takes climate experts by surprise
       Moderator Response: Regarding your last paragraph, you need to understand that weather is not climate. See Scientists can’t even predict weather
59955. Tom Curtis at 13:14 PM on 19 April 2012
       First Look at HadCRUT4
       William @17, very briefly because this is off topic - The change in mean global temperature from 1880-1889 to 2002-2011 is 0.76 C (Gistemp). As you can confirm from figure 2 above, that is approximately the same as the change from 1870 to 2002-2011. The change in ocean temperatures over the same period is 0.53 C. The difference is because land warms faster than ocean. The estimated difference from comparison of Challenger and Argos data is 0.59 +/-0.12 C, which is quite close, but if anything warmer than expected. That is particularly the case because the Challenger data may be biased warm. As the article says:

       "These numbers may underestimate the warming for a number of reasons relating to the Challenger measurements. For example, the crew worked under the assumption that the line holding the thermometer extended downward perfectly perpendicular to the surface. In reality (as they knew), it was likely to trail behind the motion of the ship, which couldn’t be kept completely stationary. That means the thermometer would measure at a depth a bit shallower than intended, yielding a warmer temperature."

59956. Daniel Bailey at 13:11 PM on 19 April 2012
       First Look at HadCRUT4
       Perhaps, william, you should read the source paper rather than a news article based on it. That would be the skeptical thing to do.
59957. william5331 at 12:24 PM on 19 April 2012
       First Look at HadCRUT4
       This site http://arstechnica.com/science/news/2012/04/modern-ocean-temperatures-compared-to-challenger-expedition-data.ars compares temperatures taken from the challenger expedition in 1870 with today's argo temperatures. The increase is remarkably small over the 140 years. I'd have thought it would be a tad greater.
59958. Tom Curtis at 11:36 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Eric (skeptic) @129, I certainly agree that regional and even seasonal forcings are very important in understanding the transition from glacial to interglacial. In fact, that is one of the two hard lessons from that transition which are not given sufficient attention. The other is that there are without doubt tipping points in the climate system. What that transition shows us is that a seasonally strong regional forcing can under the right circumstances push the entire globe into a new stable state whose mean global temperature differs by several degrees (4-6 C) from the initial stable state. It is probable that had the seasonal regional forcing in the high NH been equally strong globally and throughout the year, the same tipping point would have been crossed, but in centuries rather than millenia. Currently we are applying such a strong global forcing. We know that tipping points exist, but we don't know how strong the push has to be to push us past any given tipping point. Further, we don't know whether there are any regionally specific factors which will amplify the risk of crossing a tipping point as the NH summer insolation amplified the very weak global forcing of the Milankovitch cycle. We are gambling at very high stakes without yet knowing the rules of the game. That, however, is not strictly relevant to this discussion. What is relevant is that the WV feedback would also have been seasonal and regional in response to the seasonal and regionally strong Milankovitch forcing. As a result it would have amplified that forcing significantly even though the global Milankovitch forcing (and hence WV feedback) was weak. However, that is not particularly relevant to the debate with William Haas. That focuses on two questions: 1) Does the WV feedback contribute more to the change in the total greenhouse effect in W/m^2? To which the answer is yes! 2) Is the WV feedback sufficient without slow feedbacks to account for the 4-6 degree increase in Mean Global Temperatures from glacial to interglacial? Haas appears to say yes to this, but the answer is clearly no! In discussing these questions, we can treat the WV feedback as global, thus gaining simplicity for our treatment, without loosing clarity.
59959. Tom Curtis at 11:16 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Michael Whittemore @128: 1) Every change in temperature either globally or by latitude band prior to the Holocene (10 kyr) is natural, almost by definition. Certainly the large increases in CO2 levels and the large decreases in albedo over the period 20-10 kyr was not anthropogenic, so of course the increase in temperature from 60-90 north starting 20 kya was natural. As it happens, it was both natural and driven by the Milankovitch cycle. 2) The only forcing in the transition from glacial to interglacial was the Milankovitch Cycle. In addition to that, you had slow feedbacks (CO2 increase, CH4 increase, ice sheet reduction, changes in vegetation patterns, changes in ocean currents) and fast feedbacks (Water Vapour feedback, lapse rate feedback, changes in atmospheric dust content, changes in snow extent, changes in sea ice extent, and changes in cloud cover). The lists are not exhaustive. In order to calculate the fast feedback climate sensitivity, you can treat the changes in the Earth's energy balance due to increased GHG and reduced ice sheets as forcings, but that is merely a convenience for calculation. You should not make the mistake of thinking that they were forcings. 3) Even among slow feedbacks, CO2 or well mixed GHG generally were not the dominant players. By all accounts, the change in albedo from the change in ice sheet extent was a larger player. It is probable that for the first thousand years or so of the transition it was the dominant player, with changes in CO2 concentration not being relevant until after significant warming. Of course, changes in vegetation patterns may also have been significant players as well, with a switch from savannah to rainforest significantly decreasing albedo (although also increasing cloud cover). 4) The Milankovitch cycle did warm a large body of water. It just did it indirectly by shutting down the AMOC rather than directly by increased insolation on the body of water.
59960. Eric (skeptic) at 11:04 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Tom, I believe the things you mention are treated globally when models are not readily available to evaluate them regionally. One of the main points of the OP is that regional differences matter. I agree that the WV should not be exclusively treated globally the way I implied in 116, but I did not mean to exclude other forcings and feedbacks.
59961. Michael Whittemore at 10:09 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       @ Tom Curtis 124 You say “20 kyr: temperatures start to rise from 60 to 90 degrees north, presumably due to Milankovich forcing, temperatures start falling from 30 to 60 degrees north” I personal think that the 30-60N cooling is completely natural, you can even see that it starts to warm before the seesaw event takes place. The Milankovich cycle only warms the far north, and if the AMOC is working, it would be the main driver of climate in the 30-60N region. 30-90N only started cooling when the AMOC stops. You say “The Milankovitch forcing heated that water indirectly by shutting down the AMOC, an important subtlety Haas does not mention, but his statement that it took 2,500 years for the Milankovitch forcing to trigger the rise of CO2 levels is correct.” Haas does not say that the Milankovitch forcing triggered the CO2 rise, he says that it warmed a large body of ocean which released CO2. The forcing from the Milankovitch cycle could not have warmed a large body of ocean and forced it to release CO2. It is the trigger not the forcing. There was no forcing that warmed the southern ocean, the Earth just had an energy imbalance caused by the AMOC stopping. @ Tom Curtis 127 We are talking about forcing, the only forcing other then CO2 during the last glaciations was the Milankovitch cycle. I don’t even think it can be called a forcing, it is an energy imbalance caused by the orbit of the Earth redirecting sunlight. The only considerable forcing taking place is the release of CO2. Other GHG are short lived. To be clear, you could have everything taking place during the LGM but without the release of CO2, there really should be no added warming to the system. I know the Shakun paper says 7% of the warming took place before the rise in CO2 but I personal think that with more proxy records the global average temperature should not rise until there is a release of CO2.
59962. Daniel Bailey at 09:33 AM on 19 April 2012
       First Look at HadCRUT4
       fydijkstra is no skeptic, but a dyed-in-the-wool denier. I suggest not feeding this woolly t-roll.
59963. andylee at 08:37 AM on 19 April 2012
       Mars is warming
       While extraterrestrial climates and weather are interesting in their own right, and atmospheric compositions and temperature responses can be used to calibrate physical models here on Earth, it is irrelevant to us here whether or not it is warming on them as a result of the sun's varying output - we have infinitely better measurements of solar radiation here and its effect on our planet, which is what matters. It's just an invention that denialists use to try to mislead gullible people with something that sounds believable without all the facts. Whatever other planets are doing, in spite of the Sun's output having been at its lowest for years, our Earth is still warming.
59964. Albatross at 08:34 AM on 19 April 2012
       PMO Pest Control: Scientists
       "A behind-the-scenes look at a federal scientist 'muzzling' incident" is a must read/listen for anyone following this disturbing situation in Canada.
59965. Albatross at 08:31 AM on 19 April 2012
       First Look at HadCRUT4
       fydijkstra @8, "(do not ask me for links, this is common knowledge)." Please, this is a science site, as such please quantify your claims and provide links when attrobuting claims to scientists so that others can validate your claims. Also, thank you for coming here to demonstrate the misguided/misinformed understanding that "skeptics" have about the science.
59966. Albatross at 08:27 AM on 19 April 2012
       First Look at HadCRUT4
       I was wondering how long it would take a fake skeptic to come along to try and derail the thread. Unfortunately for them they seem to have not read the post in its entirety. Skywatcher thanks for showing just how wrong fydijkstra is.
59967. skywatcher at 07:51 AM on 19 April 2012
       First Look at HadCRUT4
       Just on the offchance that fydijkstra is not being a Poe, here's the last 15 years of HadCRUT4, using the excellent SkS temperature trend calculator and the viewer is left to decide whether they think the world has been warming since 1996 (15 years ago): 15 years of course is not generally long enough to clearly show trends in temperature data (even though I think most pepole would agree there appears to have been some warming since 1996), so lets extend the trend to the past 30 years: fydijkstra, do you still think "the warming trend in the last 15 years is zero", given the above plots from the same dataset?
59968. Tom Curtis at 07:43 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Eric (skeptic) @126, the changes in albedo from ice sheet melt in the transition from glacial to interglacial are strictly regional phenomenon, not global. Yet they are treated as a globally averaged effect in any discussion of the issue, and in any model except full Global Circulation Models. Even the Green House Effect from increasing CO2, and come to that the Water Vapour feedback are not everywhere the same because of differences in temperature between the equator and poles (among other reasons), and are treated as globally averaged effect. Choosing the WV feedback from the Milankovitch signal, and only that feedback to not be treated as a globally averaged effect is pedantry, and an inconsistent pedantry to boot. It adds nothing to the discussion.
59969. dana1981 at 07:42 AM on 19 April 2012
       First Look at HadCRUT4
       fydijkstra @8:

       "The only conclusion can be, that the warming trend in the last 15 years is zero. One does not need to be a climate sceptic to see this."

       One does, however, have to fail to understand basic statistics to believe this myth, even ignoring the massive heating of the oceans during the time period in question mentioned by Composer @9. Perhaps you should examine the temperature trends referenced at the end of the above post. As Composer @10, I hope we're just victims of Poe's Law here.
       Moderator Response:

       [DB] No Poe here. fydijkstra is a long-time fake-skeptic with a history of drive-by thread hijacking at SkS. Between mystical "Cycles" and "It's all a conspiracy" (indeed, it's conspiracies-all-the-way-down-Wednesday), no thread is safe. A sample of his work:

       "@Bernard J. Why should anyone deny these numbers? It is a huge blessing, that the earth is able to store all this heat, without harmful effect on the climate! The oceans are a perfect heat buffer. If we had no oceans, we should invent them! They are the best weapon against global warming."

       Everyone, DNFTT

59970. Robert Murphy at 07:39 AM on 19 April 2012
       First Look at HadCRUT4
       @8 "This means that there is no significant difference between 1998, 2007 and 2010. The only conclusion can be, that the warming trend in the last 15 years is zero. One does not need to be a climate sceptic to see this." It means no such thing. One does not need to be a statistician to see that taking 3 data points and ignoring all the rest of the data is rubbish. Hadcrut4 and GISS both show a warming over .11C since the beginning of 1998. Since the end of 1998 (after the huge El Nino), they show over .16C of warming. Your warming trend of "zero" is nonsense. "Some years ago, Phil Jones said, that 15 years without warming were the maximum that could be expected from the present climate models (do not ask me for links, this is common knowledge)" Please provide links anyway; you don't get out of substantiating your claims by hand-waving away the need to do so.
       Moderator Response: [DB] The "Phil Jones said" meme is off-topic on this thread (sorry).
59971. Composer99 at 07:09 AM on 19 April 2012
       First Look at HadCRUT4
       If on the other hand I have just been succesfully taken in by sarcasm/a Poe, let me be the first to admit to having egg on my face.
       Moderator Response: [DB] No Poe-egg anywhere.
59972. Composer99 at 07:08 AM on 19 April 2012
       First Look at HadCRUT4
       fydijkstra, between Foster & Rahmstorf's paper showing that warming is unabated when one accounts for ENSO & solar variation and the fact of unabated warming of the oceans, your claim appears to be decidedly false, in addition to verging on IMO baseless conspiracy-mongering.
59973. fydijkstra at 06:49 AM on 19 April 2012
       First Look at HadCRUT4
       Congratulations! It can no longer be said, that 1998 was the warmest year ever, according to CRU. They succeeded in rewriting their data. But it is a Pyrrhus Victory. Now 2007 and 2010 are both 0.01 degrees warmer than 1998, acoording to HadCrut. This means that there is no significant difference between 1998, 2007 and 2010. The only conclusion can be, that the warming trend in the last 15 years is zero. One does not need to be a climate sceptic to see this. (-Snip-)(do not ask me for links, this is common knowledge). So, even with HadCrut4 we are on the edge of rejecting the present climate models. One does not need to be a climate sceptic to see this.
       Moderator Response: [DB] Off-topic perambulations into "Phil Jones said" territory snipped. And it's "Pyrrhic".
59974. william5331 at 06:18 AM on 19 April 2012
       First Look at HadCRUT4
       Adding all these new monitoring stations is great but if they are new stations and not stations with long historical records, they will only be valuable in the future as they establish a new base line. Each time you add a new station you reset the base line. In a sense it would be better to stick with stations that have records at least back to the 1950's
59975. Rob Painting at 06:08 AM on 19 April 2012
       Cliff Ollier: Swimming In A Sea of Misinformation
       Old Mole - fixed the "previous half-decade" segment. I think technically Greenland is part of the North American continent, but it seems inconsequential to me.
59976. Eric (skeptic) at 03:00 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Part of the confusion may be that Milankovitch forcing is not a earth-averaged W/m2 forcing. There is a component of W/m2 forcing for part of the earth, specifically longer NH winters. As those winters shorten towards the end of the glacial period, there will be weather and climate changes including localized water vapor increases. But William Haas talked about global average water vapor as if Milankovitch were a simple global average W/m2 forcing which it is not.
59977. DSL at 02:13 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       So what we're quibbling about here on the basics is the definition of "forcing" where H20 is concerned. William may be insisting, if he is actually insisting, that WV is a forcing post LGM because it is the largest contributor in GHG warming. If so, no -- orbital changes are the forcing. WV is a feedback, and it is always the dominant element in GHG-based warming (but not the controlling factor -- like a bad mob film, WV is the "muscle" that does the bidding of the little guy in the shadows--Joe "CO2" Maguire--but doesn't do much on its own, unless the big big boss (orbital) needs some long-term project done -- ooo, I see a climate-as-film-noir project). Sublimation rate does not change of its own accord. WV will not increase of its own accord on the climate scale. It is always a feedback to whatever forcing. CO2, likewise, does not increase of its own accord. We don't speak of AGW-concurrent permafrost CH4 mass release as a forcing. We shouldn't speak of post-LGM WV increase as a forcing or as a trigger. I don't think that is William's intent in 113. If he clings to the idea that WV is a trigger, a forcing, then we need to question his ability to honestly engage. If, instead, he means that WV played a more crucial role than CO2 in early post-LGM warming, then that's a good, debatable position.
59978. Old Mole at 01:55 AM on 19 April 2012
       Cliff Ollier: Swimming In A Sea of Misinformation
       Two minor quibbles: "Sitting atop the Antarctic and Greenland continents are immense sheets of ice kilometres thick." Last time I looked, Greenland wasn't a continent. "contrary to popular perception, there was slowdown in the heat uptake in the upper ocean (0-700 metres deep) layers from 2003-2008, when compared to the half decade." Errr ... what half-decade? Best wishes, Mole
59979. Tom Curtis at 01:52 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Michael Whittemore @123, If you look at figure 4 in the original post, you will see the following sequence: 20 kyr: temperatures start to rise from 60 to 90 degrees north, presumably due to Milankovich forcing, temperatures start falling from 30 to 60 degrees north; 19 kyr: temperatures start falling from 60 to 90 degrees north, and continue falling from 30 to 60 degrees north. Temperatures from 30 degrees north to 60 degrees south start rising; 18 kyr: temperatures start rising from 60 to 90 degrees south; 17.5 kyr: CO2 levels start rising, temperatures cease falling from 30 to 90 degrees north. That makes it 2,500 years from the onset of the Milankovitch forcing until tropical and southern hemisphere waters were warm enough to start a steady rise in CO2 levels. The Milankovitch forcing heated that water indirectly by shutting down the AMOC, an important subtlety Haas does not mention, but his statement that it took 2,500 years for the Milankovitch forcing to trigger the rise of CO2 levels is correct. Haas may in fact just be very confused on certain points, or he may be very subtle. He may have adopted the approach of making egregiously wrong statements and then defending a reasonable position which can be mistaken for the false position he originally stated. If that is his game, by not acknowledging where he is correct, but clearly distinguishing it from his initial statements you fall for a rhetorical trap and find yourself arguing against true beliefs in the mistaken opinion that you are arguing against false beliefs. In doing so, you hand victory to the rhetorician how laid the trap. I am not saying that is what Haas is doing. As I said, he may just be confused, or even just have stated a reasonable position in a very confused way. Regardless, he has persistently made claims which are false, even absurdly false as you have highlighted; but defended the reasonable position that H2O was a significant positive feedback during the first 2,500 years of the glacial/interglacial transition. To avoid continuing the confusion, Haas needs to clearly answer my questions in 118. But to avoid continuing the confusion we need to recognize when he is right, but clearly state why what he is saying that is correct is not the same thing as, and does not support those things which he has said which are wrong.
59980. Kevin C at 01:45 AM on 19 April 2012
       First Look at HadCRUT4
       How much of the change is due to the HadSST3 and how much is due to CRUTEM4? This is rather crude and will blur the distinctions somewhat, but working from the merged land/ocean maps (I should really use the separate land and ocean files) I get the following 15 year trends 1996-2010: HadCRUT3: land: 0.255 C/decade ocean: 0.058 C/decade HadCRUT4: land: 0.310 C/decade ocean: 0.088 C/decade Difference: land: 0.055 ocean: 0.030 (Don't expect these number to match the distributed values.) Taking into account the different areas covered, the ocean looks as though it's a slightly larger effect. However because I have use the global rather than land and ocean maps I'm overestimating the ocean trend and underestimating the land trend. I guess the two play a similar role. That doesn't come across in the graphic, because the ocean change is a small change smeared over the whole map. (I will try and do the calc properly at some point.)
59981. Michael Whittemore at 00:53 AM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       I cant believe we are even wasting our time on William Haas. He clearly thinks that the 7% warming seen during LGM was global, and that it was caused by H2O. Just look at his comments below “To enhance or continue global warming is atmospheric CO2 really necessary to explain it? What about H20?” Comment can be seen here “There is no imperical data uncovered by this article to show that in the first 2,500 years since LGM that the green house gas, an increase in average atmospheric H2O did not have some roll in global warming” Comment can be seen here From the very start we have all been trying to disprove these statements. We all know that the initial forcing was the change in Earth’s orbit, H2O was not the forcing just the feedback. Even when the (AMOC) stopped, there was no added forcing that warmed the South it was just an energy imbalance with less warm water going north and more staying in the south. Even in William Haas resent comment he clearly tries to attribute H2O to global warming, even though we all know that the 7% warming seen during the LGM was nowhere near global. Just read the comment below “During the time I am talking about there was CO2 in the atmosphere but because it did not increase, its increase could not have contributed to global warming.” Comment can be seen here @Tom Curtis you say that “William Haas's comment at 113 is correct in every detail.”. You really think that William’s saying “Apparently it took 2,500 years for the Milankovitch forcing to heat a large enough volume of ocean water to effect global CO2 levels.” Is true?
59982. pauls at 00:47 AM on 19 April 2012
       New research from last week 15/2012
       #3 & 4 - the lead author, Ben Booth, has made a couple of comments about the paper and blog/media reactions at Tamsin Edwards' blog: http://allmodelsarewrong.com/how-to-be-engaging/#comment-1084 http://allmodelsarewrong.com/how-to-be-engaging/#comment-1094
59983. les at 23:31 PM on 18 April 2012
       2012 SkS Weekly Digest #15
       As an avid (non contributing) reader... Another angle on 28 is that, IMHO, denial through being Sciencey or matherterbation has just about run its course. It's been important and informative to do thorough take-downs and those are excellent resources; but now I'm always surprised when the same-old-same-old arguments are trotted out (except by politicians!) and would be equally surprised to see any new tropes which really take hold, be they sciency or 'social'... how much of a real splash did the NASA administrators joint letter really make? SkS is settling, seems to me, into more posts of excellent reviews and takes on new research. And this is right. Seems to me it's time to spend less time reacting and to take back the lead both in terms of understanding the severity and impacts of AGW and policy. We're told by Chris Mooney that 'conservatives'* are good leaders in a crisis - more and more are now realising the facts of AGW and are likely to be looking for material to use in combating it... those who've changed, or made up, their mind and come to SkS for information on AGW should find a friendly place. *I put quotes there as I'm aware the SkS contributors are actually from a very broad Church ... and not just liberal-minded, pink-o heathens ;)
59984. Kevin C at 19:28 PM on 18 April 2012
       GISTEMP: Cool or Uncool?
       On the previous post, Skywatcher pointed out quite rightly that the rectangular projection I have used in the maps can create a misleading impression, because the area is exaggerated as you move away from the equator. This inflates the apparent impact of poor coverage at high latitudes. All the conclusions of this post are based on the global temperature averages, not on the illustrations, which are provided as an attempt to explain what is going on. However there is certainly one point which needs to be demonstrated more clearly, I'll try and clarify. In determining the impact of poor coverage at a given latitude, there are three factor at play: The fraction of the Earth's surface covered by that latitude band, the amount by which temperature anomalies in that latitude band differ from the global mean, and how much of that latitude band is missing. In the case of the Arctic, these pull in different directions. The Arctic covers a relatively smaller area than a corresponding latitude range at the equator, but the temperature anomalies are changing much more quickly and the coverage deficit is much more significant. How do these effects play out? That is shown in the following figure: To generate this figure, I took the GISTEMP gridded maps and reduced the coverage to match HadCRUT3 over a 30 degree latitude band, leaving the rest of the map untouched. I then calculated a temperature series from the gridded map series. I repeated this 6 times to produce 6 temperature series. I then took the difference with the original full-coverage data. The results are shown above. Each line represents the bias added to the total temperature series by the loss of coverage in that latitude zone alone. As you can see, the Arctic is the biggest contributor to the recent cool bias of HadCRUT3, followed by the northern mid latitudes. The Antarctic actually provides a warm bias, but one which has been declining since 1998, thus actually adding to the cooling bias since that date. In fact every zone except the southern tropics has been contributing to the cooling trend in HadCRUT3 over the last 13 years. In summary: When calculating area averaged global temperature anomalies, the GISTEMP data suggests that the Arctic, despite it's comparatively small area, is the largest single contributor to the cool bias due to poor coverage in HadCRUT3. The NCDC data suffers from the same problem at high latitudes, although its mid-latitude coverage is better. The implications for HadCRUT4 are interesting.
59985. skywatcher at 17:37 PM on 18 April 2012
       New research from last week 15/2012
       #3 - wow. Clearly a result that needs corroboration / verification, but if that turns out to be right it is remarkable. Yet another blow to the fabled, mythical, "natural variations" that some skeptics tout to explain global warming.
59986. From Peru at 15:06 PM on 18 April 2012
       New research from last week 15/2012
       Nature bombshell: The Atlantic Multidecadal Oscillation (AMO) was driven by man-made aerosol pollution according to improved climate models: This is an introduction in Nature News and Views: Climate science: Aerosols and Atlantic aberrations And this is the paper: Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability If this is confirmed by more research, then man-made climate change(in this case more in the form of "global dimming" than "global warming") is after all behind extremes in events like Atlantic hurricanes and the Sahel monsoon anomalies, phenomena that have been linked with the AMO.
59987. scaddenp at 14:31 PM on 18 April 2012
       Models are unreliable
       Relevant to this discussion on skill/validation of models is Hargreaves 2010
59988. skywatcher at 14:23 PM on 18 April 2012
       Data Contradicts Connection Between Earth's Tilt and the Seasons
       Manny #20, my wording in #18 may have led to some confusion - I'm not implying that modellers made no mistake. I am implying that they have constructed a physical representation of Earth that is consistent with observational data. It is not arbitrarily constructed either, but constructed from our fundamental understanding of heat flows, radiation and the properties of solids, liquids and gases. It could be fundamentally flawed, but as it is based on physics and not on an arbitrary regression (as in the satirical example above), it has an awfully good chance of being closer to the truth than arbitrarily drawing a line through a few years of temperature data. As such, it has a very good chance of showing us what to expect over the next century, given assumptions of certain key parameters, like CO2 emissions and long-term solar activity. I've responded here as my comment relates to misinterpreting of my #18, but further discussion of models should continue on the thread as directed by scaddenp above.
59989. William Haas at 13:44 PM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       Let me take a little break here. I again want to thank you for all of the effort that has been put into this. There seems to be more than one person responding to my posts so that there are all that many more posts that I have to respond to. I guess my post 113 did not go all that badly. I do agree with quite a bit that has been said. Some of you seem to be jumping the gun on what conclusions I am going to come up with. I am not trying to espose anything that is revolutionary or sinister. I am just trying to find the truth as I am sure that your are too. I plan to continue to respond to posts in order. Some of them take additional effort on my part to consider and I am sure that, like you, I have a lot more going on in my life then just responding to posts on this site.
59990. scaddenp at 12:39 PM on 18 April 2012
       Data Contradicts Connection Between Earth's Tilt and the Seasons
       I would also say that this is heading off-topic fast, so I have responded here
       Moderator Response: [DB] Fixed link
59991. scaddenp at 12:38 PM on 18 April 2012
       Models are unreliable
       Continuing from a comment posted by Manny: Sorry, what is extraordinary about the claims of climate theory? They are fully consistent with everything else we know about physics. The time period for model validation is not some arbitrary no. (eg why stop at 100,000?) but more determined by internal variability which is calculable. However, the basic theory of surface temperature, if correct, must work throughout all times and on all planets. There are two problems going back long periods in time: 1/ computer power - full resolution, 100 year runs take a lot of muscle and time. Its more normal to look at specific parts of past time (eg LGM, ememian peak, YD, PETM etc). You dont gain a lot with very long runs. 2/ Uncertainty as to the inputs increase. ie what was past albedo, atmosphere composition, TSI etc. There are uncertainties in proxy records for those as well as uncertainties in the proxy temperature. You can say that paleoclimate temperature proxies are consistent with climate theory and proxies for climate forcings. Ditto for temperature regimes on other planets. However, paleoclimate isnt the only way to validate model - they after all push out predictions on huge no. of variables on various time scales. See Chpter 8 of that IPCC report. However, the modellers would also I am sure caution you that it is better to consider model skill rather than simple model validation. In considering the implication of the modelling for future planning, this is what matters.
59992. Manny at 11:35 AM on 18 April 2012
       Data Contradicts Connection Between Earth's Tilt and the Seasons
       Scaddenp, I looked carefully at all the figures (I am visual) of the WG1 Paleoclimate document. That's what I was looking for, thanks. And indeed, the models are validated over 1,000 years, not 100. To go back to the main topic here -- that validation of a model on too little data is misleading -- I cannot help wonder why, since the 1,000 yr temperature data is mainly proxy, did the IPCC modelers not extend their validation with more ancient proxy data? There are Greenland ice cores going back 100,000 years and Antarctic going back 400,000 years. All they have to do is run their computer longer. Extraordinary claims require extraordinary evidence.
59993. danielc at 11:22 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       LOL... grrr... I went backwards: absorb 334kJ/kg on melting, release 334 kJ/kg on freezing - any chance of correcting that last post? 3x10^15 kJ absorbed per year just to melt the ice we are losing - does that heat absorbtion have a significant masking effect on what we measure with thermometers?
59994. skywatcher at 11:19 AM on 18 April 2012
       First Look at HadCRUT4
       Excellent post, and an interesting prediction in the concluding line. I wonder if it is what we will see (a switch to using NCDC), or will the skeptics continue stubbornly using HadCRUT3 as the levels of denial bite harder and harder? One minor gripe I have is the representation of the globe as a rectangualr grid in visualisations, such as Fig 1. It's not a big gripe, as GISS have been doing it for years, and I know from personal experience that it's an awful lot easier to plot data in this way! But it does over-highlight, from a purely visual perspective (and for no other reason), the red areas at the top and bottom of the world. In the Hadley datasets also over-highlights the surface area covered by missing data. It should of course be noted, before anyone suffests otherwise, that this is accounted for in calculations of global anomalies!
59995. danielc at 11:12 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       How much of an effect does the latent heat of melting ice have? Take the present day, for example: if we are losing ~100 km^3 per year of ice (Howatt et al., 2008, PDF), that works out to 9x10^12 kg of ice melted, which would XXXXXXX absorb 334 kJ/kg, or 3x10^15 kJ per year (focused on areas where melting is most prominent). That seems like a lot to me...
       Moderator Response: TC: post edited at authors request. 1:34pm 18/4
59996. skywatcher at 10:55 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       #116 - William, you really, really need to re-read Michael Whittmore's post at #109, and mine at #108. You might note I said at #108 that we live on a wet planet, and that WV was the largest component of the GH effect, we agree on that, and a surprising amount of correct (if obvious statements in your post). Your conclusions are still miles wide of the mark though. The first crucial phrase is this, used by you: "The average amount of water vapor depends on temperature." The second crucial point is that the average amount of water vapour in the atmosphere responds very quickly to temperature change, through evaporation and precipitation, also elucidated by you. Therefore something else must force the temperature in order to keep the water vapour in the air. Water vapour alone does not do it as, alone, eventually it finds a place to freeze and increase albedo (Lacis et al 2010). Orbital forcing can change temperatures locally, thus changing water vapour locally, much as excellently described by Michael Whittmore in #109. But this is still not enough forcing to get us out of an ice age. CO2 can change WV levels globally as it is non-precipitable and well-mixed. Michael Whittmore's excellent #109 (as well as the OP of course) describes succinctly the pattern of events leading to global warming at the end of the ice age. Perhaps you would care to explain where he is wrong, and how a variable that is locally effective on timescales of a week or two can be globally effective for century-scale warming (deglaciation or current)?
59997. Tom Curtis at 10:49 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       William Haas's comment at 113 is correct in every detail. It is also correct that thetotal increase in contribution to the Green House Effect from water vapour between the Last Glacial Maximum and the Holocene is greater than the equivalent increase for CO2, or indeed for all well mixed Green House Gases. It is important that we recognize where William is right, even though we think he takes those correct premises and goes of to a completely wrong conclusion. To be clear, what Haas has stated at 113 is that Water Vapour was a significant short term feedback on the milankovitch cycle effects at the initiation glacial to interglacial transition, and that that feedback strengthened the response. Indeed, the WV feedback strengthened the original response by a factor between 2 and 4. Unfortunately, Haas has been arguing that "...starting with an ice aged earth, H2O would dominate any green house gas triggering effects." However, as he states in 113:

       "Water vapor amounts in the atmosphere vary from day to day and water leaves the atmosphere through condensation but it is quickly replaced through vaporization or sublimation. Water takes up additional heat when it melts, vaporizes, or sublimes, but then it releases that heat when it condenses or freezes."

       What he needs to recognize is that the same thing applies on the other side of the equation as well. If the WV content of the atmosphere exceeds the equilibrium level for temperature, it quickly precipitates out, so for time scales of a year or more it can be always assumed to be in equilibrium for the temperature and conditions. Consequently, the initial and significant response of the WV feedback could not have led to ongoing warming by itself. Its full effect, if no other factors were brought into play, would have been worked out within a century or so at most. Consequently, without the intervention of other factors, the WV feedback alone could not have lead to continuing warming centuries after the initial trigger. IMO, Haas needs to clearly state whether he agrees with, or disagrees with the last (and bolded) sentence. If he agrees, we have then just simply misunderstood what he has been trying to say. If he disagrees, he needs to clearly state why a factor which equilibriates over mere days can still be driving ongoing warming thousands of years later. Certainly nothing he has said in 113 suggests that it would. Of course, from the basis of the consensus on climate science, there is no issue here. WV is a strong short term feedback, but the long term increase in temperature from LGM to Holocene was driven by the far more stable factors of ice sheet melt and increased CO2 and CH4 concentrations. Because CO2 and ice sheets take thousands of years to equilibriate with temperature, there is no issue as to why they are able to drive warming over the long term. And because they are the long term drivers, they explain the transition in a way that WV cannot, even though WV contributed more to the change in the total GHE.
59998. danielc at 10:42 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       If water vapor could magically increase as a volume percentage of the atmosphere, and stay at those elevated levels over centuries... then it could be a forcing factor. As it stands, it is not a forcing factor... it is an amplifier, because it cannot and does not go into the atmosphere and stay there on its own. It must have "something" that acts to heat the atmosphere and keep it heated. The only thing that can do that is the interaction between increased insolation (the initial trigger) and subsequent enhancement and maintenance of increased CO2 levels. CO2 mixes and stays mixed for centuries. CO2 concentrations can be reduced via silicate weathering and photosynthesis + rapid burial of dead organic matter... but that process is much, much slower than the introduction and mixing of CO2 due to increased temperatures. Increased levels of H2O cannot cause global warming because they require the warming to exist beforehand. Once warming has started, the warmer atmosphere can then hold more H2O(v), and more H2O(v) is available due to enhanced evaporation, then it can begin to amplify already existing warming trends. Hence, H2O(v) is a feedback, not a driving force.
59999. skywatcher at 10:26 AM on 18 April 2012
       Return to the Himalayas
       Steve Case avoided the crucial point, mentioned by KR in #36 and myself in #30. The problem is not about whether snow melts/sublimates quicker or slower than ice, the problem is the reliability of the runoff through the year. Some years will have lots of snow, and thus there will be snowmelt runoff throughout the year, whoopee... but other years will have relatively little snow, or the snow will be spread thinly, or for whatever reason will melt early in the dry season. What happens then? How many years will it take for the late-season lack of runoff to make a real mess of local agriculture? In places like the Himalayas, and elsewhere, the reliability of runoff is the absolutely crucial factor to agriculture, and that is where having a mass of glacier ice that will survive every summer, providing runoff through the year every year, is more valuable than relying on the vagiaries of annual snowfalls. Some years all the snow will melt and some of the stored glacier ice will melt too, other years not even all the snow will melt (so the glacier gains mass), but every single year there is runoff through the whole year.
60000. Eric (skeptic) at 09:50 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       It is a sensible idea that water vapor increases can cause global warming. Water vapor increases from initial warming cannot possibly trigger runaway warming because water vapor is lighter than air. It rises, easily saturates, and condenses. There is no requirement that CO2 rise, although it rose later as an amplifier. Another thing to remember is that water vapor is very uneven during glacial periods with very dry continental interiors except for mountain ranges and glacier sources. See http://webster.eas.gatech.edu/Papers/Webster1978b.pdf for example. When the water vapor starts to even out due to Milankovitch forcing, then there is net global warming.

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