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Comments 60551 to 60600:

  1. DeConto et al: Thawing permafrost drove the PETM extreme heat event
    The trigger for this sudden destabilization was a variation in orbital configurations that resulted in warmer polar summers. -------------------------- I suppose these configurations happened several times earlier; so why did not the "PETM" happen earlier
  2. thepoodlebites at 03:39 AM on 13 April 2012
    NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Figure 2 (observations in blue): The 1998 El Nino peak looks overly damped compared to the 2010/11 El Nino, should be about equal. And the latest UAH 12-month globally averaged T is about 0.3 C cooler than the last El Nino event that peaked in early 2011.
  3. Rob Honeycutt at 02:16 AM on 13 April 2012
    NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    It should be noted that Larry Bell is actually an Architect.
  4. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    JMurphy @14 - yes, I was pleasantly surprised to see The Guardian picked up our story. No doubt they were looking for a rebuttal to the NASA letter and enjoyed ours. I noticed that the first few comments were just ad hominem attacks on SkS and James Hansen. Again, totally predictable.
  5. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    According to 'World Spaceflight,' approximately 530 people of various nationalities have been in space. So of the signers, take the number who've been in space and divide. Notable on this list is number of times in space record holder Franklin Chang-Diaz, who is currently: active in environmental protection and raising awareness about climate change, notably in his role in Odyssey 2050 The Movie in which he encourages young people to get motivated about environmental issues
  6. Data Contradicts Connection Between Earth's Tilt and the Seasons
    Thanks for the excellent simple example of bad science. I will definitely be incorporating this into my high school curriculum.
  7. Data Contradicts Connection Between Earth's Tilt and the Seasons
    Kevin C. Just quietly I think that there is much time and space for xkcd on Skeptical Science. Especially #386...
    Moderator Response: [Sph] Embedded image reference:
  8. Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
    Dr2chase. There are two points about your post at #24 that need to be addressed. First, the presence of particular species, in a particular bioclimatic niche, at a particular instant in time, does not actually tell you that they are persistent in that niche over evolutionary spans. To draw that conclusion one requires much more data than simple personal experience. Second (and it's really a reiteration of past posts as well as a segue from the first point), a species does not have to be immediately and profoundly physiologically stressed by a climatic parameter to be compromised by it. Even an apparently 'tolerable' but suboptimal climatic envelope can eventually push a species to extirpation in a particular environment, or, if it is a subtle pressure, to evolution to a more adapted species. This is the whole point of emphasising that humans are adapted in their current form to a mild Holocene climate. We are not adapted to an Eocene maximum, a scenario which would be quite possible if all fossil fuels are burned over the space of a mere few centuries. We just aren't cut our for the addition to mean temperature. Yes, our decendants could move poleward, but life in high latitudes, with seasonalities and with the degraded habitat that we will inevitably leave, will not be nearly as sweet as a palm-shaded beach is today in, say, contemporary Fiji, with a cold beer and an air-conditioned room two minutes walk away. Don't forget that future generations won't have the benefit of the once-off bonanza of energy density that we're chugging down today. Likely, they won't even have access to easily-obtained metals, as we've already exploited the best deposits. They'll be battling an ecosystem that will be massively deforested this century, when the oil peak is long past and wood (rather than the thermodynamically impossible pipedream of widespread renewables) is used in many regions to replace oil (and, in places, coal) for heating and lighting. They'll be battling a resurgence of diseases, including the very recent (by evolutionary standards) HIV which is only scratching its arse at the moment, waiting for a time when a degraded lack of technological capacity to manufacture drugs, combined with a rapidly developing resistance to those that are being used, allows it to sweep through humanity like a dose of Epsom salts. As social and educational sophistication decreases, the safe sex message will diminish, and the 'sleeper' strategy of HIV will ensure that it runs rampantly through many human populations, quite likely to the extent (or greater) that is occurs in places such as Swaziland and Botswana today. And there's TB, and malaria, and a host of enteric viruses, and many cryptic exotics that are simply waiting for the current human monoculture to flip them out of whichever hidden corner in which they're currently percolating. A large proportion of these diseases will all do very well in a warmer world, thank you muchly, not matter how clever the post fossil fuel generations are at shading themselves under trees, in houses, or at the beach. From physiology to ecophysiology, we're not greenhouse animals - no matter how much we can toy with basking in the sun. Heck, as persistence hunters we evolved away most of our fur - and largely during the passage of the last ice age, in fact. We did this because it allowed us to prevent overheating in what was not a greenhouse climate. And yes, it was warm in Africa, but the fact of nakedness still helps to contextualise how we adapted to a thermal upper limit. And granted, we're agricultural these days, more than predatory (although many would disagree). However, if we eschew the advantage of a high protein diet evolution might decide to select for new humans that don't have quite such a high-maintenance brain - and then adjusting to a warm climate becomes more a matter of doing what the environment tells us, and not what our descendants might want to tell it to do. In ten years, or 50 years, or a hundred years, certainly many humans will deal with the heat. Most will, in fact, as long as something else doesn't get them first. But in the longer term, on more evolutionary scales... not so much.
  9. Michael Whittemore at 23:41 PM on 12 April 2012
    Shakun et al. Clarify the CO2-Temperature Lag
    I was looking at figure 4 and could not help wonder if CO2 lagged the temperature rise when you left out the 30N-90N proxy's. It would seem to me the reduced cooling in the northern regions are so low, that they draw down the other proxy's. The basic idea is most of the planet may have lead CO2, but due to the large cooling in the far north, when averaged it makes it look like all of the northern hemisphere lead CO2. It might had only been the far north that lagged CO2. I think with more proxy's and a batter understanding of just how cold it was in the north might bring CO2 back into a lagging state. I graphed the 80 proxy's below.
  10. Eric (skeptic) at 23:20 PM on 12 April 2012
    Shakun et al. Clarify the CO2-Temperature Lag
    The feedback effect of water vapor is not just a result of temperature but varies with climate regime. For example in glacial climates the storm tracks are weaker and further south, see http://www.springerlink.com/content/r8m3117000188x52/ and folk.uib.no/cli061/pdfs/thesis.pdf. That leads to less latent heat transfer than the modern climate. Thus, the change in weather patterns from glacial to interglacial causes more warming than just from increase in WV (about 10% average) and other positive feedbacks. Another evening of water vapor (causing warming) comes from the increase in vegetation (reduction of deserts). Some of that is incorporated in fig 5 above. It is important to point out that we cannot predict the changes in weather patterns that will occur from modern CO2 warming. Some predictions are for less meridional flow (net global warming), some predictions are for more. That is obviously just one factor of many.
  11. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    @ Captain Pithart Alex (Skip) Larsen is also misspelled. It's actually Axel Larsen. He co-authored a book in 2009 titled "Satefy Design of Space Systems".
  12. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Sphaerica @3, It feels like shame and embarassment, those 8 astronauts - heroes of our childhood, but objectively, it ain't necessarilly so. How large is this sample among the total population of retired astronauts (+cosmonauts - let's be impartial)? I guess very few, less than couple %. I am optimistic that the silent majority is far less silly than those 8 vocal deniers, so I still like those heroes. Until some proper poll/survey proves otherwise: i.e. climate denialism among retired astronauts be stronger than among average population with similar education level.
  13. DeConto et al: Thawing permafrost drove the PETM extreme heat event
    A fascinating analysis. I wonder, though, about the conclusion that "we should perhaps worry more about the far greater stores of fossil carbon that we are now quite deliberately exhuming and putting into the atmosphere..." On 4 March, this site published a piece about the increases we can expect of fires in Northern forests & peatlands, made possible by thawing permafrost & ignited often but not exclusively by lightning. Enough peat (if burned) exists in those regions to render the planet uninhabitable, said that previous article. Seems to me that, though our fossil carbon emissions are "getting the ball rolling," the thawing peat is of equal or greater concern?
  14. Captain Pithart at 20:49 PM on 12 April 2012
    NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    "Tom Ohesorge" is a typo, it's "Thomas E. Ohnesorge". Several signatories also signed the Oregon Petition, for example Deiterich, Doiron, Kraft. Larry Bell is the one from Forbes. It would be interesting to have the total amount of *life years* these guys have :) George Mueller is born 1918, for example. p.
  15. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Tom Curtis, As Thomas Wysmuller is Dutch you should try the Dutch version of his last name Wijsmuller, however the result is exactly the same
  16. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    I see Dana's post is now in The Guardian in the UK. The comments should be interesting...
  17. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    You people at SkepticalScience amaze me with the speed you turn this around. I was wondering if you knew who Thomas J Harmon and Tom Ohesorge were. I have a sneaking suspicion that Harmon might be a security officer, given a Google+ page with a same name person claiming to be retired from NASA. I wouldn't want to have this guy bothered though. Perhaps you've demonstrated enough with the administrators involved. I would caution that I think there is a faint hint of validity in what the astronauts are getting at. Perhaps if NASA were to link to the hard science, like refereed papers are required to do, then the nutjobbery would have no real recourse but to go back to denying actual science rather than statements on NASA. While a web site is not a peer reviewed paper, NASA being NASA, might like strive for a higher standard than producing statement without reference. I also hope that NASA comes out firing and demands what specifically these signatories are claiming is not supported by science. Also it's not just the signatory Schmitt that is an Exxon funded Heartland board member, but also Walter Cunningham is on the board of Heartland institute and has ties to Exxon Mobil through the Tech Central Station. I wonder how many others receive Exxon funding.
    Moderator Response: [Sph] Please provide references for your assertion (and theirs) that NASA has produced a "statement without reference." That whole part of their letter confuses me. NASA conducts an amazing amount of science, generates a lot of knowledge and papers that contribute to the knowledge, and produces what are fairly detailed and informative articles. What exactly are these "unproven remarks in public releases and websites" to which they (and you) are referring?
  18. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Those making the noise are far worse than that, because any sensible pediatrician or dentist will refer them straight back to a surgeon. What the contrarians are doing is more like trying to treat cancer with homeopathy. The homepathic practitioner will just take their money, give them a vial of water, and reassure them there is nothing to worry about because doctors can sometimes get things wrong.
  19. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    In the OP, Dana says of the letter's signers that "... we have a bunch of former administrators, astronauts, and engineers who between them have zero climate expertise and zero climate science publications." I had noted that one of the signatories was billed as a meteorologist, so a little further exploration was in order. As it turns out, a search of Google Scholar for author: Wysmuller turns up no papers published by any "Tom Wysmuller" at all, so it turns out Wysmuller is not a published scientist in any field. At his very own anti-global warming web site, where Tom Wysmuller offers to lecture on global warming for a fee (from universities) or for free (for high schools) we learn that he was an intern at NASA, but that since then he has been: "•Admin Director of Govt. Operations at Pratt & Whitney, where he wrote the code that solves the Polynomial Regression Algorithm now resident in millions of Texas Instruments calculators. •Insurance Executive & Board member of insurance and other companies/orgs. •President of NYU’s Alumni Association. •Vice Chairman, The New Netherland Museum, where in May, 2001, the New York City Council issued a proclamation honoring his historical contributions." Curiously given above comments @9 and @10, from linkedin we learn he was on the Board of directors of Delta Dental. Finally, from Marc Morano we learn that he worked for the Royal Netherlands Meteorological Institute (although Morano mistranslated the organizations name) as a "weather forecaster". So Dana is right. Even from the most promising candidate, there is no actual experience as a climate scientist, or in the professional study of climate. What is more, from Marc Morano we learn that he believes that,
    "The largest contributor to carbon dioxide in the atmosphere is the warming oceans"
    which gives a the quality of evidence that the former NASA employees consider "proven". Ironically, in one essay he even uses a Steven Goddard reproduction of the IPCC First Assessment Report estimate of medieval temperatures based on Central England Temperature series back to the Little Ice Age, and an educated guess based on European anecdotal evidence before that. I guess "proven" means something entirely different when the conclusions are ones that you like.
  20. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    R Gates @9, sorry. Can't be done. The dentists and plumbers are too busy signing the Oregon Petition.
  21. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Might as well assemble a team of retired dentists or plumbers to write such a letter. Oh, but of course that wouldn't have the desired impact would it, even though their knowledge of climate dynamics would be about the same.
  22. Shakun et al. Clarify the CO2-Temperature Lag
    Shakun is a great paper and nuance is just the right word, but check out his curves for insolation, antiphase between hemispheres at lat 65.They are sooo slow. Why here, Why now? Thermite needeed. More nuances coming IMO.
  23. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Interesting that these retired gentlemen make no mention of the scandalous work done at NASA Langley: The evidence, according to Bruce Wielicki, lies in the decades of climate records that are revealing how humans are "driving our system a thousand times faster than it's ever been driven before." ... "You can't believe a single scientist, but you can believe thousands of scientists," he said, referring to several peer-reviewed science organizations–such as the IPCC group–that have arrived at the same conclusion: Climate change is happening. An astrophysics friend with some inside contacts at Johnson Space Center recently told me of a group of 'old geezers' who would argue against climate science - they're big fans of JCurry. Anyone surprised?
  24. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Pogo is a term used to refer to oscillations in rocket fuel arising from uneven acceleration of said rockets as they launch. It does, however, trace etymologically back to the pogo stick toy. To not stray too far myself, I think that it's great that the Administration has responded promptly to this kerfuffle. I also think it's a shame that these former employees decided to ignore the work of current employees at NASA, and work of climate scientists from around the world, at gathering the very evidence that they say wasn't ever examined, the very evidence that has been presented publicly and on international scale for 20+ years now.
  25. Shakun et al. Clarify the CO2-Temperature Lag
    DB - thanks! That's exactly the paper I was thinking of. danielc #79, I think the answer to your question is 'no'. AFAIK there's no threshold level above or below which the WV feedback is particularly effective - the effect scales smoothly with increased temperature. Raise the temperature, add some WV. To go into more details - WV's impact is logarithmic with increasing temperature (see Tom's comment above), as with other greenhouse gases, as they are all 'bites' being taken out of the longwave IR spectrum. We would thus expect to see the impact of WV decreasing slightly with higher temperatures/concentrations of WV. However, there's so much WV in the atmosphere in relation to CO2 or CH4, that doubling the quantity is a lot harder, and so the feedback warming effect of WV will probably be effectively linearly correlated with temperature forcing. William Haas #80, you're not providing any evidence to support you ideas. Why would H2O be more readily available, given CO2 is more effective a GHG at lower concentrations? How would that WV last in the atmosphere long enough to melt glaciers and so sustain the warming (see the paper linked by DB to my above post)? "... probably a lot more going on ..." is just hand-waving, or, to be frank, appealing to leprechauns.
  26. Doug Hutcheson at 12:40 PM on 12 April 2012
    NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    The list of signatories covers a wide range of expertise in irrelevant studies. I was particularly impressed by:
    Dr. Harold Doiron – JSC, Chairman, Shuttle Pogo Prevention Panel, 16 years
    Pogo Prevention? Is that, like, to do with things that bounce up and down, like temperatures on Earth? Well, I can see the relevance then - the guy is an obvious expert, right up there with the proprietor of Monckton's Shirt Shop. WUWT managed to add value to the cause, with this little snippet:
    When Chris Kraft, the man who presided over NASA’s finest hour, and the engineering miracle of saving Apollo 13 speaks, people listen.
    Yes, Anthony, that's the point: when someone with an irrelevant expertise agrees with your position, you choose to listen. Shame you won't do the same when a relevant expert speaks. One comment at WUWT speaks about Harrison Schmitt thusly:
    He’s also the only geologist to reach the Moon, and geologists have a much better “world view” about the impacts of climate change than people from any other branch of science.
    Well, I'm glad that's settled, then: a geologist who has been to the moon must be an expert on everything to do with his home planet. (Takes note to self: must ask Harrison Schmitt for a second opinion on everything SkS says, to be sure I am not being misled)/sarc
  27. Shakun et al. Clarify the CO2-Temperature Lag
    So perhaps you can name a plausible mechanism in contrast to the stated, and quite simple one (i.e. that orbital forcing drove up temperatures enough to release CO2 that then amplified the forcing signal)?
  28. Shakun et al. Clarify the CO2-Temperature Lag
    danieic, Thank you for your efforts. I understand a triggered reaction but since the world is not thermite your analogy works just so far. I think that starting a simple camp fire would also be a good analogy. Modeling is not really evidence. Especially in an ice age environment, H2O is a more readily available green house gas than CO2 that can be released with just a little surface heating. It is the oceans that heat up so very slowly from year to year that help moderate the reaction but only the very surface of the ocean, or a glacier for that matter, has to be heated to release significant amounts of water vapor. Yes, not only does the water vapor need to be produced but the atmosphere needs to be warmed to contain a larger amount. There was probably a lot more going on than just green house gasses that caused the climate to change over a period of more than 10 thousand years and the evidence that we have only gives partial information on what really happened. CO2 may have played an important part but I do not see any evidence that it had to be CO2 that caused the ice age to end.
  29. Shakun et al. Clarify the CO2-Temperature Lag
    Is there a sustained level of, or a sustained rate of change of CO2 concentration that is required to sustain consistently elevated H2O(v) levels? (Did I word that right? -- What I mean is: Is there a CO2 threshold beyond which water vapor in the atmosphere will provide strong and sustained positive feedback, or is there a particular CO2 input level relative to the starting level that is required to trigger and maintain the water vapor feedback?
  30. Shakun et al. Clarify the CO2-Temperature Lag
    William Haas @74, the forcing of CO2 does not scale with the CO2 concentration but with the logarithm of the CO2 concentration. Consequently for a broad range of CO2 concentrations there is a constant change of CO2 forcing by 3.7 W/m^2 per doubling or halving of concentration. As the CO2 concentration at the LGM was 180 ppmv, and in the year 2000 it was 370 ppmv, the change in CO2 forcing is just over 3.7 W/m^2. The relevant formula is that deltaF = 5.35 * ln(C/C0) where deltaF is the change in forcing, ln is the natural log, C is the CO2 concentration and C0 is the initial CO2 concentration. This formula breaks down for very low and very high values of CO2 concentration, but is valid for the range of CO2 concentrations experienced over the last 600 million years of Earth's history. The water vapour contribution to the GHE also scales with the logarithm of concentration, although I do not know the exact formula. However, concentration increases exponentially with temperature so that the net effect is an approximately linear increase of GHE contribution with rising temperature. The major problem with assuming a water vapour driven emergence from the Ice Age is that it implies a very strong water vapour feedback. The total change in GHE between LGM and Holocene is somewhere between 50 and 100 W/m^2. If water vapour has driven that change from a small initial increase, then the climate sensitivity to a small perturbation in water vapour would be in multiple degrees. As ENSO causes fluctuations of plus or minus 5% in the water vapour content of the atmosphere, a strong El Nino such as 1998 would drive us into a new regime with radically increased temperatures. Clearly that does not happen. The reason, as others have pointed out, is that water vapour precipitates rapidly out of the atmosphere. Consequently it's concentration is strongly controlled by temperature. You should also recognize that the change in CO2 forcing between LGM and Holocene is very well established. If water vapour has a very strong self fueling feedback effect, it must have an equally strong feedback effect to the change in CO2 forcing, not to mention changes in albedo etc. So if you rely on a theory of water vapour driving the transition between glacials and interglacials you must then provide an ad hoc theory as to why the CO2 forcing did not result in an equally strong additional feedback.
  31. Shakun et al. Clarify the CO2-Temperature Lag
    Thanks, skywatcher! And Thanks Moderators for both correcting my poorly formatted post and for the link to that article!! I like this site.
  32. Shakun et al. Clarify the CO2-Temperature Lag
    William Haas, water vapour is a feedback, not a forcing. It cannot be a forcing because it precipitates out of our atmosphere in a few days. A greenhouse effect composed entirely of water vapour would collapse to an ice-house as the water vapour precipitates out and gets locked up in ice sheets (IIRC there's a paper describing this). Thus, the amount of water vapour in the atmosphere essentially depends on the temperature of the atmosphere. The rapid hydrological cycle leads to two things - water vapour easily gets into the atmosphere as a response to warming, and it easily precipitates out again as rain. [danielc - all you need is any kind of warming to add a bit to the water vapour feedback, not a large forcing to initiate it as in your analogy]. CO2 forcing provides the backbone for the other feedbacks to operate, as the CO2 cannot precipitate out quickly, lasting hundreds of years in the atmosphere. A feedback incorporating CO2 release, as occurred during deglaciation, leads to extended warming, long enough to melt some of the ice sheets, reinforcing the warming through a change in albedo. Our great CO2 release experiment is doing the same thing, only using a much larger and much quicker CO2 release, where the CO2 release does not depend on the behaviour of ocean ventilation... Water vapour feedback article on SkS
    Moderator Response:

    [DB] Try:

    Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature, A. Lacis, G. Schmidt, D. Rind and R. Ruedy, 2010

  33. Shakun et al. Clarify the CO2-Temperature Lag
    @William Haas: The increase in sunlight would not have triggered anything *on its own without the prior pre-conditions being met* -- (there are many documented cases where orbital forcing/milankovitch cycles reached the same basic arrangement of insolation and heat delivery without producing a massive and global glacial meltdown... It's that the orbital forcing trigger was pulled at a time when the conditions in the Northern Hemisphere were ripe for a magnified positive feedback response to that trigger. Let's look at it this way: Do you think that over the last 30 or so million years that Antarctica has been ice-bound and covered with that sheet, there have or have not been orbital configurations (Tilt, Wobble, Precession, Ellipticity) that have delivered large and sustained highs in Southern Hemisphere insolation? I would bet that there have been such events, and that folks who model these things and try to push the orbital cycles back beyond 5 mybp have isolated just such events... And yet none of them triggered any kind of self-reinforcing feedback in anything like the way that the NH has responded to the orbital forcing over the last 3 my or so... (at least none that I know of ... and I am certainly willing to find out/admit ignorance/learn something new!!) So, even if it is the H2O(v) that is the big bad heavy hitter in the later stages of the meltdown, it's pretty clear from the available evidence and modeling that 1) these events require (or used to require!!) an orbital trigger. That the orbital trigger cannot set off the H2O(v) runaway by itself, it needs to "stage up" using more readily available, more readily releasable, GHGs to reach the threshold where there is continuous and sustainable increases year on year in GHG release and H2O(v) maintenance. I like to think about Thermite reactions when considering how this must work : 1) if you have a chunk of iron and a chunk of aluminum and a good fuse (magnesium), you have all the material you need to make thermite with not much effort.... but you cannot do it with the materials in their starting state! 2) Both the iron and the aluminum must be in the proper oxidation/reduction state, and the heat trigger must be arranged in such a way as to produce the proper amount of heat to overcome reaction barriers. 3) so only after you've powdered both metals and ensured that the Iron is in the Fe(III) oxide form and the Aluminum is pure metal (no oxides), and then mixed/homogenized the powders ... then you must trigger the reaction by attaining an ignition heat, where the magnesium comes in. So you light a match (low temperature, short lived, tiny reaction), and that lights the magnesium (much higher temperature, but slow burning, calm reaction). The lit magnesium melts the two metals at a high enough temperature that the molten aluminum (very hot!) reduces the oxidized iron in a massively exothermic (even hotter!) reaction that requires a lot of activation energy. The reaction is essentially self-sustaining, given enough reactants mixed appropriately - it supplies its own oxygen, it produces enough heat to keep the reaction going, and under water, it is hot enough to generate hydrogen, rather than quenching or smothering. So, with a little bit of sugar burning (in the muscles of your hand), you ignite a match that produces a bit of heat for a short time.... that triggers a much hotter but slow burn in the magnesium, which in turn triggers a massively hot, extremely exothermic, self-sustaining, un-smotherable reaction between Al and Fe2O3. If reactions like that can be easily envisioned and reproduced (I've done it in my backyard, and even did it with copper instead of iron, just for laughs), and involves multiple stages and triggers to climb the entropic ladder, then why would it be hard to imagine that a bit of change in insolation can trigger a bit of warming that can release a bit of CO2 that can thaw a bit of glacier... That releases a bit more CO2, thaws more glacier, and wham... up the ladder you go, releasing enough CO2 to trigger enough melting to trap enough warm water in the right place to release even more CO2... that heats the place up enough to get the H2O(v) reactions rolling, and suddenly... Some avalanches do start with a butterfly landing on a pebble...
    Moderator Response: TC: Phrase between asterixes added by request; all caps turned to bold to comply with comments policy.
  34. Shakun et al. Clarify the CO2-Temperature Lag
    Tom Curtis, thank you for your efforts and all the information you have supplied. I would think that CO2 forcing would be in proportion to the amount of it in the atmosphere. How much CO2 was in the atmosphere at LGM and how much today? I realize that the water vapor effect was less during the LGM then it is now but so was CO2. But that does not really matter. What matters is what changed because it is what changed that kept the temperture increase going. According to the article it was solar energy by means of orbital cycles that triggered the end of the ice age. According to the article CO2 levels at first did not rise because it took a while for the oceans to experieice significant warming. You state that "as temperatures continue to rise, the water vapour will contribute proportionately even more to the total GHE than does CO2" It seems to me that H2O levels alone are enough to explain the GHE effect part of triggering the end of the ice age.
  35. Scientist Sets Record Straight on Medieval Warming Research
    Update from Syracuse available here: “It is difficult for the lay public to make informed decisions about contentious issues — particularly those concerning climate change, conservation and preservation — which require objective, scientific research and discovery when news reporters fail in their duty to write accurately about the science behind the issues.” Failure to write accurately about science is a job requirement in some camps.
  36. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Can I post my intemperate comments now? They got (rightly) snipped from previous threads... but it was so much fun writing them, that I would love to reproduce them in full. If you let me, I promise that they will be even more choc-a-bloc full of inflammatory prose! :)
  37. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Somebody should ask Schmitt if he saw any other Earths out there in the great black void of space, just in case he's wrong on his assertions about this one. You'd hope that Moon astronauts, being the only people to have seen how small the Earth is in space with their own eyes, would appreciate the value of protecting the only planet we have. A good article Dana and a good response from NASA there too. Is this kind of angry letter all the so-called skeptics have left now? It would seem so. Do they not actually have any science they can stand behind, any plausible alternative explanations explaining the full body of evidence? It would seem not.
  38. Shakun et al. Clarify the CO2-Temperature Lag
    William Haas @72, in the year 2000, CO2 contributed 31 W/m^2 of a total 152.6 W/m^2 greenhouse effect. Water vapour and clouds combined to contribute 112 W/m^2. At the Last Glacial Maximum, assuming a difference in temperatures of 7 degrees C, the total greenhouse effect dropped to about 120 W/m^2, but CO2 forcing dropped by only 4 W/m^2. If we assume a temperature difference of 4 degrees C as calculated by Shakun et al, the XXXXXXX total greenhouse effect XX dropped to 114 W/m^2. That leaves a change in greenhouse effect of between xxx 33 and xxx 40 W/m^2 to be explained, primarily by changes in Water Vapour and clouds. Even if we assume all other factors (which combined for a total 7 W/m^2 GHE in 2000) drop to zero contribution, that still leaves around xxx 26-43 W/m^2 of reduced GHE to be explained by reduction in the Water Vapour effect. These calculations do not take into account either albedo from dust, or the increased pole to equator temperature gradient during the LGM. If they are taken into account, they will explain a significant portion of that xxx 26-43 W/m^2. Never-the-less it is XXXXXXXXXXXXX highly probable that the reduction in water vapours contribution to the GHE in the LGM was greater than 15 W/m^2, and hence greater than the proportional reduction to the CO2 forcing. Therefore CO2 was a more important contributor to the total GHE at the LGM than was H2O. What is more, this is just what we would expect given the rapid decline in the saturation vapour pressure of H2O with temperature: Conversely, as temperatures continue to rise, water vapour will contribute proportionately even more to the total GHE than does CO2. Another was of saying this is that as temperature increases, so does the relative* strength of the water vapour feedback. Running that back to the LGM means that the water vapour feedback was weaker during the last glacial than it is now. That means it was even less able to trigger a self fueled runaway effect as you are suggesting than it is now. * added in edit, 10:17 AM Edited 3:25 PM of 14/4/2012 to correct error in calculation as detailed below.
  39. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    When I was in 6th grade we all went down to the auditorium to share a moment of silent meditation wishing the best for the 3 astronauts on Apollo 13. I used to see astronauts as heroes having the courage to push the envelope as a way to better mankind and to seek the truth. Using their status and past accomplishments to express their own ignorance in an area of science completely beyond their experience is an embarrassment. It makes me feel like I wasted a part of my childhood respecting the wrong people for the wrong reasons. It shouldn't diminish what they contributed and what they accomplished -- but it does.
  40. Shakun et al. Clarify the CO2-Temperature Lag
    67 Sphaerica Thank you for your reply. But in the article I read things like: "The first warming was indeed triggered by orbital cycles". So it is not CO2 that started the warming that caused atmospheric H20 to increase because ice is melting, water surfaces are warming, and the atmosphere is warming, increasing its capacity to hold water vapor. It is really the increase in sun light that triggered the whole thing. As more water vapor enters the atmosphere the warming continues alowing even more water vapor to enter the atmosphere. Yes water does precipitate out but it is quickly replaced. Water is still the dominant green house gas in the atmosphere and was even more so during the ice age when even less CO2 was present. I do not understand how CO2 is needed to explain what happened.
  41. Climate Scientists take on Richard Lindzen
    Chris G - Lindzens apology was a positive indication. Unfortunately, he's been pushing much the same set of incorrect models since his (quite interesting, but quickly disproven) 2001 "Iris" paper. Which with fairly minor changes has been published yet again (3rd time?) as Lindzen and Choi 2011, in a rather off-topic journal, after being rejected from more on-topic publications. I'm not seeing any signs of recognizing and learning from past errors...
  42. Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
    dr2chase. Thanks for that. I have little to no experience with humidity. During extended hot periods here it's quite common to find several dead bees in the garden (when you find the courage and stamina to go outside again).
  43. Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
    Regarding bees/bats etc. Bees, I know from personal experience, are gloriously happy in a Florida climate. Africanized bees, which migrated north from Brazil, we can presume are pretty healthy in current-tropical climates. Bats do well in Florida, and do well in current-tropical climates. As a general rule, Florida was (and is) a much buggier place than Massachusetts or northern California. There's no doubt a maximum temperature for pollinators, but we're far from it right now in the US. People lived in the South (including Florida) back before air conditioning, though it wasn't a popular choice. If things go as predicted, I expect millions of people will leave Florida, much as millions of people moved to Florida in the previous century. Don't get me wrong, we are definitely rolling the dice on our present course, and they're loaded against us, but there's a difference between godawful costly and end of civilization, never mind end of a species. It's likely that there will be excess deaths, but elsewhere, and our civilization has developed and bumbled along in the face of excess deaths elsewhere for centuries, never mind the awfulness of calling that "civilization". What we call civilization, survived.
  44. Shakun et al. Clarify the CO2-Temperature Lag
    JosHag, Thanks!!!!!
  45. Data Contradicts Connection Between Earth's Tilt and the Seasons
    While I wouldn't normally post an xkcd cartoon on SkepticalScience, there is a time and place for everything: (It took me a while to get the final panel, but I'm a little slow.) [Mouseover text: Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'.]
    Moderator Response: [Sph] Added mouse-over text to cartoon image.
  46. Shakun et al. Clarify the CO2-Temperature Lag
    Great post. It is maybe interesting to combine it with Schmitt et al 2012, which shows a drop in δ13Catm after 17.5 kyr BP explained as a result of upwelling old carbon-enriched waters in the southern ocean. They also report a small rise in δ13Catm before 17.5 kyr and, like Shakun, link it to rising temperatures: "After a very small increase in δ13Catm at the very end of the glacial, a sharp drop in δ13Catm starting at 17.5 kyr parallels the onset of increasing atmospheric CO2. Taken at face value, this would point to an early SST rise that preceded the onset of the CO2 increase." ... "Note, however, that this 0.06‰ excursion is within the uncertainties of our data and that other effects could also lead to this small enrichment in δ13Catm." @Sphaerica #69, the Shakun paper can be found here.
  47. Data Contradicts Connection Between Earth's Tilt and the Seasons
    For a moment I thought you may be Bob Tisdale. A genuine Tisdale would have used at least 30 graphs to illustrate the same point.
  48. Climate Scientists take on Richard Lindzen
    Bob, Also, the fact that he sent an apology when he made a misrepresentation indicates to me that he has integrity. (Anyone ever seen an apology from Watts or Monkton?) And, he doesn't deny basic things, like that the greenhouse gas effect exists. I think mostly he has cornered himself into an incorrect model, and is unwilling or unable to walk over the wet paint.
  49. Shakun et al. Clarify the CO2-Temperature Lag
    68, Lazarus, If I'm reading the above analysis properly (I don't have access to the paper):
    1. Orbital changes cause a retreat in ice sheets
    2. Retreat causes warming and disruption of the the Atlantic meridional overturning circulation (AMOC)
    3. The disruption of the AMOC plus the warming causes a faster increase in temperatures in the Southern Hemisphere
    4. The increase in temperatures in the led to a rise in CO2
    5. The rise in CO2 caused further increases global temperatures, accelerating both the SH (Antarctic) and NH temperature increases, which releases more CO2.
    So the answer you're looking for isn't simple, but it's all there:
    • Initial trigger was orbital changes causing ice melt (albedo changes)
    • Ice melt added an unexpected factor in affecting the AMOC and a differential in warming in the two hemispheres
    • Warming in the Antarctic proceeded more quickly, starting before CO2 release -- CO2 was a feedback in response to the warming -- so CO2 lagged Antarctic temperatures by 800 years
    • Warming in the Northern Hemisphere proceeded more slowly, primarily driven by CO2, so CO2 (still, as a slow feedback) drove global temperatures higher and led temperature increases.
    Really, in the end, nothing has changed except to get a more detailed model of the interplay of factors and events.
  50. NASA Climate 'Skeptics' Respond with Science! Just Kidding.
    Response from NASA If I may paraphrase slightly, 'Hey, you guys are full of it... and feel free to publish some actual scientific research on the subject if you want anyone to take you seriously.'

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