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Comments 60201 to 60250:

60201. William Haas at 09:22 AM on 20 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       87 Tom Curtis Again thanks for yours and everyone elses efforts. What is really missing in this article is a plot of the Milankovitch forcing during the time in question in high enough resolution to make any sense. From the best that I could find, change in solar irradiance caused by orbital cycling peaked in the north roughly a thousand years before the period that we are talking about and was decreasing during this period. There are those who argue that Milankovitch forcing is not strong enough to do much of anything but I am just going to assume that Milankovitch cycling started the whole thing. Clearly the Milankovitch could have only triggered the climate change but not sustain it because the Milankovitch forcing in the north was decreaseing during the entire 2,500 years but temperatures were increasing. I understand that the orbital cycling did not change the total earth irradiance, just the balance so that Artic summers would have recieved a little more sun light and hence a better oportunity to melt some ice. During this 2.500 year period, according to the article, CO2 levels did not rise but temperatures did rise. According to green house gas theory models, if the global average temperature rose than water vapor average values rose. Water vapor is the green house gas that causes the majoriety of the green house gas heat trapping effect. Therefore during this time an increase in water vapor content would have increased heat retention in the atmosphere which would have caused temperatures to rise even further. If this did not happen then the green house gas effect models that are used today to predict global warming must be incorrect. It is not clear that this water vapor effect had any real effect on climate change. I think that what allowed climate change during this period to be triggered were varations in ocean currents. I think that albedo change and unknowns had some effect but it was ocean currents that caused the the climate to trigger. During the age of the dinasours North and South America were not connected so world ocean currents were much different especially around the equator. It was after North and South America became connected that current ice age cycles began to ocour. The oceans of the world act as a huge non-linear thermal capacitor. We could be looking at some sort of natural frequency of the oceans. Most of the analysis of this data that I have seen does not get much further then simple correlation analysis. I think that work should be done to try to detect phemonenon such as orbital cycles and to compute climate change transfer functions. Who knows what phenomena may be detectable if the appropriate analysis is performed. I do not think that transfer function analysis will be of any value to predict the weather but climate change is a whole different game. No I do not think that water vapor changes alone can cause anything beyond changes in local weather. The climate is not going to spontaneously change because of a chance riae in relative humidity. I do not believe that our climate is inhaently unstable because of green house gas positive feedback and I assume that it has not been modeled as such.
60202. John Russell at 08:21 AM on 20 April 2012
       Global Surface Warming Since 1995
       In my arguments with them, I think I've see where the average fake sceptic goes wrong with these graphs. The problem seems to me that most of them basically draw a line across the top of all the peaks and then claim there's been no warming. In reality, of course, the peaks represent a only small percentage of the warming going on and it's the bulk of time between the peaks and troughs, when there is a steady but unspectacular rise in average temperatures, that tells the real story.
60203. scaddenp at 07:50 AM on 20 April 2012
       Return to the Himalayas
       jsk - yes, one of the many expensive options that go into costing adaptation. One question though. Who should pay for these dams? The people dependent on the water, or the people responsible for changing the atmosphere?
60204. BKsea at 07:26 AM on 20 April 2012
       Global Surface Warming Since 1995
       To me the most egregious misrepresentation of Santer is taking the statement that 17 years of data coverage are needed to compute a trend and then using two individual monthly points separated by 17 years to show no change. These are not even close to the same thing.
60205. jzk at 07:12 AM on 20 April 2012
       Return to the Himalayas
       Sphaerica @48, Unless humans respond by building reservoirs.
60206. muoncounter at 06:16 AM on 20 April 2012
       Return to the Himalayas
       Steve Case #47: Nonsense; I make no mention of the 'source.' The source is irrelevant - what matters is that many people derive their freshwater from meltwater-fed rivers. Both references I've posted here and here suggest the same thing: Take away the water impounded as snow and ice and you go thirsty. It would be beneficial to the discussion if you could produce some source material to support your opinions. "Just because a glacier is gone or becomes static, doesn't mean the rain and snow that falls won't continue to flow there." I have no idea what that even means. However, if you are suggesting that glacial meltwater falls as precipitation solely on the same catchment, you are sorely mistaken. Compiled by UNEP's Polar Research Centre GRID-Arendal and experts from research centers in Asia, Europe, Latin America and North America, the report says the larger glaciers may take centuries to disappear but many low-lying, smaller glaciers, which are often crucial water sources in dry lands, are melting much faster. -- emphasis added
60207. dana1981 at 04:21 AM on 20 April 2012
       Global Surface Warming Since 1995
       Slioch @3 - the question here is whether it's warming, not the causes of that warming. That quote may not be clear, but it's correct.
60208. Bob Lacatena at 04:09 AM on 20 April 2012
       Return to the Himalayas
       Steve, If I may, the important thing to remember is that for all intents and purposes a glacier (in terms of water supplies) is like a reservoir. It holds a vast amount of water. In times of increased precipitation the amount of water it holds can grow. In times of decreased precipitation the amount of water is holds will shrink, but its mere existence continues to provide water to human communities with a fairly steady flow. It is only the complete destruction (evaporation or physical drainage) of a reservoir that spells trouble, even if the amount of precipitation remains the same, because without the reservoir, the water is not necessarily there for the taking when you need it. The same thing applies to water fed to communities or ecosystems by glaciers. Glaciers are like regulators. When precipitation is high, they trap the water for later. When precipitation is low they continue to deliver water at a steady rate. When the glacier is gone, this natural regulation goes away with it. The reservoir is gone, and the inhabitants must live or die at the mercy of the uneven nature of the weather.

       ...receding glaciers have consequences, such as ... disappearing fresh water supplies for billions of people.

       Does that statement make more sense now, given this context?
60209. Steve Case at 04:08 AM on 20 April 2012
       Return to the Himalayas
       muoncounter at 03:11 AM on 20 April, 2012 In a round about way you are making the argument that the glaciers are the source of fresh water. Precipitation and nothing else is the source. And you know what the IPCC says about precipitation in a warmer world. You tell me that we can't count on precipitation falling on the same areas that were dependent on glacial melt for their freshwater. (-snip-). Glacier melt snowmelt or rain may very well flow to an arid region. Just because a glacier is gone or becomes static, doesn't mean the rain and snow that falls won't continue to flow there.
       Moderator Response:

       [DB] Now you are just being argumentative. Precipitation is the source of glacial mass. In a warming world, glacial accumulation zones shrink and their ablation zones increase. Glaciers are declining in mass with much greater losses to come.

       All of this has been pointed out to you previously, but still you persist in what amounts to an agenda of stubbornness and patent refusal to learn.

       Off-topic diversions snipped.

       Just because answers and information are provided to Steve doesn't mean that he will then deign to learn from it.

60210. Slioch at 03:53 AM on 20 April 2012
       Global Surface Warming Since 1995
       re "The term essentially means "we can't rule out the possibility that it isn't warming." I don't think that is a very clear way of expressing what "not statistically significant warming" means in this context. I would prefer to say, "we can't rule out the possibility that the observed warming was caused by relatively short-term natural factors rather than by the long-term effects of human actions."
60211. muoncounter at 03:11 AM on 20 April 2012
       Return to the Himalayas
       Steve Case#44: "I object..." The issue here is not seasonal melt that clearly provides fresh water. The issue is long term loss of ice mass - and that fresh water is on its way to being salt water. These concerns are stated very clearly: “Glaciers serve as a natural regulator of regional water supplies,” ... "Glacier changes, especially recent melting, can affect agriculture, drinking water supplies, hydroelectric power, transportation, tourism, coastlines, and ecological habitats." ... ... as the world’s glaciers continue to melt and shrink, over time there will be less water to sustain the communities that have come to depend on that meltwater. This seems an obvious point; what is the basis for your continued objection? "in a warmer world there will be more precipitation. " Once again, indeed. But you cannot count on that increased precipitation falling on the same areas that were dependent on glacial melt for their freshwater.
60212. Bob Lacatena at 02:57 AM on 20 April 2012
       Return to the Himalayas
       43, Steve, While I won't discount your experiment as uninteresting or useless, it does little to add to an understanding of the problem. In a nutshell, looking through your comments, your understanding of glaciers is insufficient and is tainted with 'real world, common sense' assumptions that are in many cases wrong or at best incomplete. If the topic interests you as much as it seems, I'd suggest that you spend an afternoon looking for (reputable) information on what glaciers are and how they work. They're a fascinating, varied and surprising area of study. It's well worth the time spent. Then, armed with a better understanding of the complex mechanics behind glaciers and their behaviors, you can revisit some of the scientific statements concerning how they will be impacted by climate change, in order to arrive at a better understanding of what those statements mean and eventually to arrive at a point where you can answer your own questions.
60213. Steve Case at 02:38 AM on 20 April 2012
       Return to the Himalayas
       skywatcher at 10:26 AM on 18 April, 2012 You of course have a point. If the snow in the mountains varies year to year some of that variability will be reflected in the runoff. A 100% direct relationship or something less? Do natural and manmade impoundments modify the flow? How about ground water? Besides, there are lots of watersheds that don't have glaciers or very large ones and people live there. Is this "Problem" so absolutely crucial that I must change my life style? Just remember this conversation started out because LarryM wrote in Global Warming in a Nutshell that receding glaciers have consequences, such as disappearing fresh water supplies for billions of people. I object to the claim that fresh water supplies will disappear for billions of people because of receding glaciers. And once again, the IPCC tells us that in a warmer world there will be more precipitation.
       Moderator Response:

       [DB] "And once again, the IPCC tells us that in a warmer world there will be more precipitation."

       And, once again, you take an overly simplistic view of things. As was pointed out to you earlier (did you not read it?), some areas will stay the same, some will further dry and some will get even wetter.

       In the case of the Himalayas, much of the area (if not all) is projected to receive both less precipitation and to warm even more.

       Precipitation Changes:

       

       [Source]

       PDSI Changes:

       

       [Source]

60214. Steve Case at 02:15 AM on 20 April 2012
       Return to the Himalayas
       Philippe Chantreau at 09:48 AM on 18 April, 2012 I ran two variables, all with the same volume of snow and same weather conditions. I packed snow into two identical plastic tubs and weighed them to make sure the same mass of snow was in each. One went in the freezer, the other the microwave to melt the snow. Then it went in the freezer when it was frozen out they came and went on the wall. I did the same with loosely packed or fluffy snow. Fluffy snow melted faster than the same mass of ice and packed snow melted slower. The different volume you see is that of the ice, the loosely packed fluffy snow produced a smaller volume of ice. The test ran over several days. You assert that there are no useful results from I did. What experiments have you done? What experiments have you found in the literature addressing the issue that are useful? If the moderators know of a more appropriate thread for this topic, I would appreciate their input.
60215. KR at 23:13 PM on 19 April 2012
       GISTEMP: Cool or Uncool?
       Kevin C - It would also be interesting to look at distance correlation factors per band in the RSS/UAH data, to see whether the regions not covered could be extrapolated as per the GISS data. And to see what that extrapolation might indicate. My guess would be that both would shift to higher trends if polar regions were considered as well, as opposed to left out as they are now.
60216. muoncounter at 22:43 PM on 19 April 2012
       Models are unreliable
       Manny's argument, if it can be called one, cuts both ways. Here is an extraordinary claim: We can burn fossil fuels without regard to our impact on the global environment. Where is the extraordinary evidence that supports this extraordinary claim? Or do we just carry on with business as usual, on the sole basis of 'that's what we've always done'? Particularly when we know without question that our actions do indeed impact the environment in both directions - see ozone, smog, the Black Triangle, the Clean Air Act, Asian brown clouds, etc.
60217. Anne-Marie Blackburn at 22:32 PM on 19 April 2012
       Polar bear numbers are increasing
       John, I'm working on the intermediate rebuttal so I'll update this one once I've finished it. Not sure if this has been posted on here, but here's Steven Amstrup's view on the misreporting/misrepresentation of the recent report published by the government of Nunavut.
60218. Nimbin Hippie at 21:33 PM on 19 April 2012
       Cliff Ollier: Swimming In A Sea of Misinformation
       Getting back to Ollier's article, he says "Port Macquarie Hastings Council was recommending the enforcement of a "planned" retreat because of alleged danger from sea-level rise". Actually the Council hasn't made any recommendation at all. The consultant engineers' report is still on exhibition, and it is about beach and dune erosion. Sea-level rise is only mentioned as another factor which may or may not make erosion worse. The Port Macquarie News has been dealing with the issue in a calm and factual way. When the Australian published its first article with the theme of callous Council to boot out frail old couple after bad advice based on dodgy sea-level models then all reasonable discussion ended. Ollier's article is also remarkable as it manages to convey the idea that the CSIRO relies only on models instead of actual observed data. The tide gauge at Darwin ceases to exist. "Where is this place?" He also attempts to refute the observations at a specific site by bringing in an irrelevant world satellite mean, when as fig. 7 above shows, there is good agreement between satellite and tide gauge in this region.
60219. Kevin C at 20:03 PM on 19 April 2012
       GISTEMP: Cool or Uncool?
       WheelsOC: The UAH dataset description gives coverage as from 85S to 85N, excluding some terrain over 1500m - coverage is poor over the "Tibetian Plateau, Antarctica, Greenland and the narrow spine of the Andes". While TLT temperatures are not directly comparable to surface temperatures, it would certainly be very interesting to see how the maps compare. It would be interesting from a social perspective to publish a HadCRUT3 dataset with a coverage bias correction derived from the UAH and/or RSS data. In fact there is scope for a range of indices of this kind and a suite of online analysis tools which provide a uniform view across all the data in any combination. And I guess (and this is not my native field, so my guesses are wrong more often than not) that the agreement will be much better than the current incomplete data. We could also do a mix-and-match on land and ocean series. This is beginning to sound like real research rather than a part time blog effort though. I guess I should look at funding channels for public engagement with science·
60220. Michael Whittemore at 17:36 PM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       @Tom Curtis It would seem I have to make myself clear, I was talking about the Milankovitch cycle affection the 30-60N region and that I don’t think the cooling you pointed out was caused by it. I also disagree that what Hass said is correct. The Milankovitch cycle did not warm a body of ocean that released CO2, there was no forcing involved that warmed the southern ocean which caused the release of CO2. The Milankovitch cycle was a trigger, a very small one at that. I stand by my point regarding CO2 being the only real forcing occurring. The orbit change and the stop of the AMOC did not add in substantial forcing, it really only caused an energy imbalance that would have corrected itself over time. I think Haas is wrong when saying H2O played any major part in a global forcing. H2O did not add anything to the energy system. I know that when there was a build up of warm ocean water in the south due to the AMOC stopping, water vapor would have played a part in the warming process, which eventually released CO2, but regarding the actual forcing that caused an actual global warming, CO2 is the only major added forcing. I understand that everything you have said is correct Tom, I just don’t give Haas the benefit of the doubt when it comes to his misguided comments.
60221. chuckbot at 16:30 PM on 19 April 2012
       Global Surface Warming Since 1995
       Oh dear, it's C3Headlines. They seem to be a comedy goldmine. For example, this: http://topologicoceans.wordpress.com/2012/04/04/graphing-out-loud-curves-and-lines/ and this: http://tamino.wordpress.com/2012/01/29/some-questions-for-rutan/
60222. Philippe Chantreau at 16:17 PM on 19 April 2012
       Shakun et al. Clarify the CO2-Temperature Lag
       I'm not sure what William Haas' position is exactly. It seems he would like to shift the "control knob" role to water vapor. That would be hard to square with pretty much everything known about paleoclimate. In addition, it wouldn't exactly make anything easier, as burning fossil fuels releases massive quantities of water vapor along with the CO2.
60223. WheelsOC at 16:04 PM on 19 April 2012
       GISTEMP: Cool or Uncool?
       How's the polar coverage for the satellites that give us the RSS and UAH lower troposphere datasets, compared to NCDC and HadCRUT3? Do they also show relatively hot poles where those records lack coverage?
60224. scaddenp at 14:34 PM on 19 April 2012
       Models are unreliable
       "I call these claims extraordinary". Why? Would "firing off our entire nuclear arsenal at once might lead to mass extinctions", or "a 10km asteroid impact, will lead to mass extinctions" be extraordinary claims? I would say no - both a consistent with known science. The context for that original quote and its basis from Laplace, refer to ideas that are in breach of all known science. The denialist community is making the extraordinary claim that modifying our atmosphere with a known radiative gas is somehow, in defiance of quantum mechanics and laws of thermodynamics, not going to result in a warming climate. The question over model skill is whether they are better than predicting the future than a naive assumption.(eg that man cant affect climate). The models demonstrably have that skill. Instead, Manny, you seem prepared to bet the future on the basis that known physics is wrong. I rather doubt you make similar bets against in science in other spheres (eg what you Dr tells you). Would this be because you perceive that any solution would violate your political ideals?
       Moderator Response: TC: Text edited to change all capitals into bolded. The comments policy applies for everyone.
60225. 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.
60226. 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?
60227. 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?
60228. 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
60229. 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."

60230. 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.
60231. 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.
60232. 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.
60233. 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.
60234. 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.
60235. 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.
60236. 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.
60237. 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.
60238. 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.
60239. 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.
60240. 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.
60241. 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?
60242. 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.
60243. 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

60244. 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).
60245. 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.
60246. 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.
60247. 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".
60248. 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
60249. 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.
60250. 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.

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