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Comments 59951 to 60000:

59951. 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?
59952. 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.
59953. 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

59954. 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).
59955. 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.
59956. 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.
59957. 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".
59958. 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
59959. 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.
59960. 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.
59961. 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.
59962. 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
59963. 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.
59964. 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.)
59965. 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?
59966. 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
59967. 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 ;)
59968. 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.
59969. 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.
59970. 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.
59971. scaddenp at 14:31 PM on 18 April 2012
       Models are unreliable
       Relevant to this discussion on skill/validation of models is Hargreaves 2010
59972. 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.
59973. 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.
59974. 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
59975. 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.
59976. 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.
59977. 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?
59978. 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!
59979. 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
59980. 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)?
59981. 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.
59982. 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.
59983. 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.
59984. 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.
59985. Philippe Chantreau at 09:48 AM on 18 April 2012
       Return to the Himalayas
       Steve Case, your "crude" experiment is too crude to yield any useful result; whatever you observed while doing it can not be applied to this discussion. I don't know that it can be applied to anything. The snow and ice blocks are of different sizes and obviously different densities. What are the beginning and ending water masses for each? What are the surface to volume ratios for each? What results do you get if you start with identical masses (i.e. kg of water in snow form and 1 kg of water in ice form)? The angles of the pictures and the distance to the subjects are different for the before-melt and after-melt, and the blocks also appear to have been moved, as the background is not the same.
59986. Philippe Chantreau at 09:39 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       William, I superficially read your posts so far. Can you clarify for me the following: are you making the argument that water vapor acts as a forcing when it is somehow injected in the atmosphere (whatever the mechanism)?
59987. Daniel Bailey at 09:16 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       William, multiple people have engaged you multiple times in an attempt to correct your errors. You display no indication that you have read and understood their efforts. You are simply, fundamentally, wrong on the ability of water vapor to be a temperature forcing of climate in any capacity. Until you grasp the difference between the forcings and the feedbacks, you will not be able to overcome your block in this matter.
59988. William Haas at 08:59 AM on 18 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       82 skywatcher We are talking about the first 2,500 years after the LGM. The article states that during that time 7% of the warm up that ended the ice age occoured but that atmospheric levels of CO2 did not increase. During that time water surfaces dominated the earth much as they do today and as they have for billions of years. During the ice age, ice sheets developed where there are none today but they did not cover the entire earth. Ice is also a water surface. Water molecules can pass directly from an ice surface into the atmosphere through sublimation. So plenty of water was available 19,000 years ago to pass into the atmosphere just as there is plenty of water available today. We are talking about climate. So the day to day levels do not matter, it is the average amount of water vapor in the atmosphere that matters. As average temperatures increase so will the average amount of water vapor. Water vapor is a green house gas and in fact it is the domanant green house gas. Just how dominiate water vapor is, is a matter debate, but from my reading, all who believe in the green house gas theory agree that water vapor is the green house gas that accounts for the most warming. The primary reason for this is that during at least modern times there is usually 100 times more water vapor in the atmosphere than there is CO2. The average amount of water vapor depends on temperature. If the average temperature increases so does the average amount of water vapor in the atmosphere. This idea is used in modern models of how CO2 contributes to global warming. Increased levels of CO2 traps more heat which raises temperatures. The rises in temperatures causes more water vapor to enter the atmosphere because higher temperatures increase the atmosphere's ability to hold more water vapor. The additional water vapor causes the atmosphere to trap even more heat. Because of this, water vapor is considered to be a positive feedback to the effect of adding more CO2 to the atmosphere. As such H2O amplifies the effect of increased levels of CO2 on global warming. I would think that most people on this site would understand that and for that matter even defend it. During the first 2,500 years since the LGM, CO2 levels did not rise but temperatures did rise. This is all according to the article. I am not desputing it nor am I making this up. The feeling is that Milankovitch forcing was the cause. To raise CO2 levels it takes more than just surface heating of the oceans to have any significant effect. Apparently it took 2,500 years for the Milankovitch forcing to heat a large enough volume of ocean water to effect global CO2 levels. But to increase average H2O levels in the atmosphere all that is needed is for the temperature of the atmosphere to increase. The article says that temperatures did increase during this period of time so that H2O levels must have increased and the increased levels of H2O must have added to the warming. If this is not the case then current models that predict that increased CO2 levels are warming the globe and that incorporate H2O related feedback and or amplification, must be all wrong. 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. 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.
59989. shoyemore at 07:53 AM on 18 April 2012
       Global Warming in a Nutshell
       davpat, KR answered your questions in #27, and Tom Curtis answered them again in #36. Tom also has a great post at this site on the greenhouse effect. I think you should take the discussion further at that post, if you are still confused. I found this review article an excellent introduction to the greenhouse effect. http://geosci.uchicago.edu/~rtp1/papers/PhysTodayRT2011.pdf
59990. Kevin C at 07:50 AM on 18 April 2012
       First Look at HadCRUT4
       OK, I think I've got it. Here are the stations in that cell: 526520 389-1005 1483 ZHANG YE 19511988 101951 526570 382-1003 2789 QILIAN CHINA 19562007 301956 526810 387-1030 1367 MINQIN CHINA 19392010 101939 527540 373-1001 3302 GANGCA CHINA 19572007 301957 527650 374-1016 2682 HAO-MEN CHINA 19562007 301956 528560 363-1006 2743 GONGHE CHINA 19532007 301953 528660 366-1018 2262 XINING CHINA 19362011 301936 528680 360-1014 2072 HEY-IN CHINA 19562007 301956 528760 363-1029 1905 MINHE CHINA 19562007 301956 528890 361-1039 1517 LANZHOU CHINA 19322007 101932 529570 353-1007 3290 TONGDE CHINA 19542007 301954 But: Only one has data for the 2006-2010 period: XINING Only one has data for the 1996-2000 period: LANZHOU So we've got a break in continuity for cell reporting. The homogenisation algorithm would normally take care of this, but it is failing in this case. Why? Because XINING has data before 1996 and after 2000, with a big gap in the middle. I suspect that there are two different stations here which require different homogenisation offsets, but which are reporting as a single station. This is the sort of situation (fortunately rare) that the BEST scalpel algorithm is designed to address.
59991. kampmannpeine at 07:31 AM on 18 April 2012
       New research from last week 15/2012
       thanks for this beautiful anthology !
59992. Kevin C at 07:15 AM on 18 April 2012
       First Look at HadCRUT4
       Peter H: Yes, interesting isn't it. I'm guessing those cells have only a single station in, and it is producing unrepresentative readings due to either local influences or a fault. I'll try and track down the China cell. CRUTEM3/4 reject stations which are more than 5 sigma from the cell mean, but that only works if there are at least 3 stations in the box. You can get an even clearer picture of the frequency or otherwise of unrepresentative stations with this applet from Nick Stokes, which shows a globe of anomalies for every weather station for November of last year. You can see a few which are obvious outliers - there's an obvious one in Romania (just West of the Black Sea).
59993. littlerobbergirl at 06:32 AM on 18 April 2012
       First Look at HadCRUT4
       Fig 3 says it all thanks dana i can stop trying to wonder about the wwii anomaly at least. Well done on the guardian comments on the 'joking' piece btw - up there with monbiot for the denyer response and post numbers :D
59994. actually thoughtful at 04:54 AM on 18 April 2012
       2012 SkS Weekly Digest #15
       The issue of this thread is subtle, in my opinion. For the last year or so, it seems SkS has taken direct aim at deniers, both scientists and non-scientists. There has been some good to come from that - the Pielke Sr. conversation was illuminating. I can quickly get Monckton rebuttals (although he rarely shows up in US discussions of climate change). But I think something has been lost as well - the positive focus on science has been reduced to accommodate the direct interaction with the deniers. We become, in the eyes of the world at large, just another WUWT - only with a different point of view. We are unwitting/unwilling partners in the deniers war on science - just by refuting them (at least directly). Perhaps adding a series just reviewing the science would help? Ari Jokimaki provides great summaries - perhaps one or more of those could be expanded into a full SkS post? Also, posts that tie current events into the discussion (like pointing out that a warm March in the US does not mean the entire globe is setting records (the "G" in AGW)) would be very helpful. Sadly, at this moment I can't volunteer to write the those articles, and I hasten to add this is the best site on the subject - by far - without any changes.
59995. Andy Skuce at 03:42 AM on 18 April 2012
       Return to the Himalayas
       Snow is more susceptible to sublimation than thick glacier ice, so, other things being equal, a given mass of snow will contribute less to the runoff than the same mass of glacier ice. It's a question of how much surface area of the frozen water cystals is exposed to the air and direct sunlight. Anyone who has experienced a Chinook wind has seen snow disappear into thin air quite quickly, while any ice on the ground lingers longer. Some of the water vapor produced by sublimating snow will, of course, re-precipitate locally as rain or snow.
59996. Peter H at 03:01 AM on 18 April 2012
       First Look at HadCRUT4
       Re the animated gif, isn't that bright blue square in China odd as indeed are the red one in central Africa and a red square on the American west coast?
59997. Rob Honeycutt at 02:41 AM on 18 April 2012
       Return to the Himalayas
       It seems to me that California, where I live, can be a good case in point with regards to this subject. The SF Bay area's water supply, as well as farming in the central valley, are reliant upon the snow pack from the previous winter. That snow pack can be very different season to season. A year or two in succession with low snow pack can quickly deplete the bay area's reservoir systems and then we are subject to water rationing. If it were not for the reservoir system which buffers these swings we would have dramatic swings in water supply. Glaciers operate similarly to buffer the water supply to vast down stream populations (much greater than SF, by far). Currently the glaciers of the Himalayas act as reservoirs for those populations. There can be normal swings in the snow pack from season to season but overall they are going to have a constant supply of water because of the buffering effect of the glaciers. What we are doing with climate change is, we're effectively dismantling that glacial reservoir system, AND we are increasing the variability of season to season precipitation. The situation is clearly a looming crisis. I have no doubt that we have already committed to melting the Himalayan glaciers completely over the next 2-300 years. The only possible response will be to build a series of massive dams in those same basins to mimic what the glaciers naturally do.
59998. Daniel Bailey at 02:00 AM on 18 April 2012
       Return to the Himalayas
       This whole thread is getting quite off-topic and derailed. Steve's most recent comment being "case" in point. And subject to deletion as not being compliant with the posting policy of this site. Mauri sent me some info for a post on the Himalayan glaciers. I will try to put that into shape over the next few days to try to put to bed some of this nonsense.
59999. KR at 01:53 AM on 18 April 2012
       Return to the Himalayas
       Steve Case - Your point? My telepathy is in the shop, and your post is a bit content-light. Observations indicate less total snow volume, the temperature records clearly show warmer/earlier springs, and both are affecting spring/summer snowpacks feeding agriculture downhill.
60000. John Russell at 01:04 AM on 18 April 2012
       2012 SkS Weekly Digest #15
       Re: Issue of the Week To me, accepting the realities of AGW comes about because I've taken the time to build up in my head a simple working model of how the Earth's climate works and how global temperatures are maintained. Having done that, everything new I read fits into place and makes sense. The problem of dealing with the 'don't knows' is that they don't carry this model around in their heads and so when they hear ridiculous denial claims -- which are often simple and (superficially) seem logical, they cannot apply them to any in-built model and thus see the flaws. A very basic example of this is the idea that global warming can actually produce a cold winter and/or a wet summer; which seems completely counter-intuitive unless you have the model in your head -- at which point it becomes logical. Another example is the one that leads people to say, "how can a trace non-toxic, seemingly inert, gas be harmful?" So to answer the question: the key requirement is to help people construct the model in their heads of how climate works and then how human actions are impacting on it. Of course, even more important, is how we generate the interest in people in order that they're driven to start creating this personal model. Without their personal model in place, you're just appealing for people to trust your expertise or judgement: which can work up to a point. But it can also break down once someone more charismatic comes along.

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