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  1. Does the rate of climate warming matter ? I have read recently that the rate of CO2 release by humankind is 30 times faster than natural means alone and that this is unprecedented in the history of climate on the earth.

    [Response: This is old news! You might want to check out some of our earlier posts: here, here, and here for example. -eric]

    Comment by pete best — 26 Mar 2006 @ 11:28 AM

  2. I didn’t see a mention of Antarctica’s temperature in 2100, which is also likely to be warmer than during the last interglacial — is this because the Antarctic ice sheets are assumed to be slower to respond, and won’t be as important by 2100?
    What are current estimates on sea level rise this century? Outside of the Pacific Island States, many of which will be lost, where else will there be major impacts?
    Thank you so much for your service!

    [Response: Warming doesn’t have as direct an impact on most of Antarctica, which is so high and so cold that even modest warming won’t cause it to start melting. Still, there is already significant melting and glacier retreat on the Antarctic Peninsula (see here). And since much of the Antarctic ice sheet is grounded below sea level, it may ultimately be more sensitive than Greenland. As for sea level rise details, a good place to start is: the IPCC report section on the subject. -eric]

    Comment by Karen Street — 26 Mar 2006 @ 1:53 PM

  3. ‘And since much of the Antarctic ice sheet is below sea level’
    Eric … surely you meant: ‘And since much of the Antarctic ice sheet is grounded below sea level’

    [Response: Yes indeed, thanks! –eric]

    Comment by llewelly — 26 Mar 2006 @ 2:54 PM

  4. Dear Sirs/Madam’s, In all of the research I can sort through I have found little refference to weather modification and global warming trends. I have reviewed the site:


    Curiously, what I find interesting is the all out assault against high Cirrus clouds (water vapour ice crystals formations)with chemical aerosols. I have made many ground observations of artificial cloud formation of high cirrus clouds being absorbed into chemical trails from jets. I think that untill a full disclosure of these practices and thier ramifications and data associated with such projects is discussed openly, then the truth of artificial cloud cover and infra red heat trapping in the lower level atmosphere can help expose the artificial and perhaps deliberate heating of clouds and atmosphere. This of course impacting the sea ice maximum and minimum extents.
    Also Dr. Dmitriev , a prominant russian scientist reports a new layer of mono atomic water vapour in earths atmosphere. Do you have any confirmation of this new gas layer?
    thanx, george

    Comment by george naytowhowcon — 26 Mar 2006 @ 3:30 PM

  5. OK you people. Where do we go from here please?

    Thanks to Father William I have gone down this road to learning about our planet : thanks William.

    I really dont like what I am reading. I understand almost everything except the truly technical bits but even there I can cope with my knowledge of basic physical principles which serve everyone in good stead : understanding “Albedo” is a piece of cake with the reflectiveness of earth (and yes and by the way, I support more satellites properly positioned to measure that), or, add energy and everything expands and becomes more violent and unpredictable – good for children that, and I hope that Mr Beck has the energy and time to do a “Childs Guide” to add to his site. Mr Beck : I can do a consumer response survey with my grandchildren if you want.

    I dont really care whether the timescale is 50 years or 500 years : it is the outcome that is worrying and requires attention – the lead times for social action are often enormous.

    So what to do?

    A number of my friends have been presented by me with the question : if you were to die today would you be able to say that the world is a better place today than when you were born?

    Not an unfair question but very difficult to answer. My mother, aged 83, when asked this paused for what seemed a long time and then said : “For medicine ; yes”.

    Well, it seems to me that that question, on improving the way we live together, is the real challenge.

    Comment by Eachran — 26 Mar 2006 @ 3:34 PM

  6. Leaving aside the question of sea level rises, what are the implications of increased icemelt for warming rate? Elsewhere on this site you pointed out that icemelt forcing creates greater feedback than CO2 forcing. So assume that the sensitivity total is 2.9 degrees, but icemelt is at a higher rate than projected so we get more feed back. Can you translate that into a sensitivity equivalent so that perhaps 2.9 degree sensity is the equivalent of a 3 degree sensitivity due to the increased feedback or whatever? Or is that asking too much of current modeling?

    Comment by Gar Lipow — 26 Mar 2006 @ 7:01 PM

  7. Jim Hansen wrote in the UK daily newspaper The Independent, 2/17/06: “The last time the world was three degrees warmer than today – which is what we expect later this century – sea levels were 25m higher. So that is what we can look forward to if we don’t act soon. None of the current climate and ice models predict this.” When would he have been referring to?

    I’ve read about studies suggesting that sea levels reached over 20m above present around 420,000 – 400,000 years ago. But ice core study says that CO2 and CH4 are at their highest for 650,000 years, so presumably the warmer period described by Hansen was farther back still?

    [Response: He is referring to the mid-Pliocene (around 3 million years ago). The sea level estimates for 400,000 years ago you refer to are probably overestimates, I think there is a paper by McManus and colleagues that discusses that, but I can’t find the reference. – gavin]

    Comment by Jim Roland — 26 Mar 2006 @ 8:14 PM

  8. So, if the evidence indicates that during the last interglacial most Arctic and some Antarctic ice fields melted, and ocean levels rose to 4-6 meters above present levels, does that not at least suggest that human contributions to the present warming act largely to increase the rate (not the extent) of warming? Is it not probable that the ice caps would melt eventually regardless of human intervention?

    [Response: Not all interglacials are created equal. The peak NH summer insolation at the Eemian was signifcantly stronger than it was for the mid-Holocene – and it has been decreasing since. See the figure 1 in the Overpeck et al paper. – gavin]

    Comment by Robert Beck — 26 Mar 2006 @ 8:20 PM

  9. Re #7: Robert Beck, according to orbital forcing the globe should be in a slight cooling trend now. So, on a long-run average, I would expect small increaes in frozen water.

    Have you looked into Coby’s site, listed on the sidebar: A Few Things Ill Considered? This might clarify some matters.

    Comment by David B. Benson — 26 Mar 2006 @ 8:39 PM

  10. The nineteen foot line is clearly visible in the Exuma Cays in the Bahamas.

    Comment by Thomas Lee Elifritz — 26 Mar 2006 @ 8:46 PM

  11. Has anyone published data on changes in particulate content and chemical makeup of the paleo ice cores? Seems to me that signifcant changes in these would have a huge impact on ice sheet melt rates but I haven’t seen any published information.
    J. Cuddy

    Comment by j Cuddy — 26 Mar 2006 @ 9:58 PM

  12. Hi Eachran,

    I am thinking about a “dummy’s” guide, a children’s guide demands a bit more graphical artist skills than I have! Have you seen this site?
    Your grandchildren may appreciate that.

    Comment by Coby — 27 Mar 2006 @ 12:20 AM

  13. Lately we have heard over and over again that the computer models have been wrong. Dr. Hansen recently was quoted as calling the computer models of Greenland’s glaciers worthless. That is a strong statement. The modelers say the models have badly underestimated the damage. The skeptics say the models are just wrong. This time, both could be right.

    So, why bother with models? Why not study nature and not computer programs?

    BTW, if the models have badly underestimated the damage, there are two possiblities:
    1. The models are wrong.
    2. Nature is wrong.

    I prefer to think the models are wrong. In that case, there are several possiblities:
    1. The modelers have just made small errors in their parameters.
    2. There are factors the modelers simply don’t know about or haven’t included in their models.
    3. Some, or many, factors interact one with the other, making any attempt at modeling the weather a joke.

    You would think the modelers would be embarrassed by the failure of their models to “predict” the future. I haven’t noticed a lot of introspection from the modelers. Now, they will just tweak them a bit to make them comform to current measurements.

    [Response: You’ve made several disconnected statements and perhaps one of us will provide a more lengthy response as time permits. I’ll just note that confusion of weather and climate doesn’t help whatever case you are trying to make. If you really mean that you disbelieve that weather forecasting is possible, then you are in the good company of some well known political figures, who have disbelieved, say, model-based forecasts of hurricanes off the coast of Lousiana… Now, if you are talking about modeling climate, that’s a somewhat different topic… -eric]

    Comment by joel Hammer — 27 Mar 2006 @ 12:21 AM

  14. “*Note that we don’t actually have good constrains on the rate of sea level rise from the penultimate glacial period (~140,000 years ago) to the last interglacial (LIG, ~125,000 years ago). However, we have very good data on the more recent glacial-to-interglacial transition, between about 14,000 and 7,000 years ago. During that time, sea levels rose at an average rate of about 11 mm/year, and at rates much higher than that for short intervals.”

    Aren’t CO2 levels now much higher than they were in either of those periods? And only going to get higher? Why should the rates from either of those events be applied to the current situation?

    Come to think of it, wasn’t there also a period called the “topsy turvy century,” where truly fantastic sea level fluctuations occurred? Is that at all relevent to the situation we face now?

    Exactly how useful are either of the two periods mentioned to understanding the situation we have now?

    I’ve read this blog entry a couple of times. The title is “How much future sea level rise? More evidence from models and ice sheet observations.” You mention some papers and articles that have come out recently. Then you address the title of your entry with the following (a few things picked out):

    “What does all this news mean in practice? Reading the editorials in Science, and quotations from various researchers in newspaper articles, one might be under the impression that we should now expect “catastrophic sea-level rise” (as Science’s Richard Kerr writes). Of course, what is catastrophic to the eye of a geologist may be an event taking thousands of years. …

    Coastal managers, real estate developers, and insurance companies, at the least, would be wise to continue to take such predictions seriously.** As Don Kennedy and Brooks Hanson write in the lead Editorial, “accelerated glacial melting and larger changes in sea level should be looked at as probable events, not as hypothetical possibilities.””

    What exactly are your predictions for sea level rise over the next 100 years. Spell it out explicitly. 3mm a year is nothing. One century takes it .3 meters or 12 something inches. Over a century. No real estate developer has such a long term view of real estate unless it can be gotten for essentially nothing. If you can’t flip it relatively quickly it is meaningless. Insurance companies take a longer view, but it is more like decades, not centuries. And what the hell is a coastal manager? I’ve never heard of this office in my life.

    You certainly have some idea in your head of what you expect to see. Yet you managed to say very little in your article. Bland, inoffensive, nothing to inspire any controversy.

    But what exactly do you REALLY think will happen? Are you steering clear of coastal real estate? Looking for a position away from the coast? What? Threat of sea level rise overblown? Expect it to stay 3mm a year for the next thousand years? Rise to 5mm? What are you expecting?

    [Response: Bland, eh. If you are bored, you might try this: Day After Tomorrow. As for me, I wasn’t planning to inspire controversy actually, since as far as I’m aware this isn’t controversial. Sea level is going to rise somewhere between 1/2 and three feet in the next century or so. It could be much much more (say, two times as much). If you live 1/2 foot above high tide level (as many many many people do), either way it is a big deal. Am I personally steering clear of coastal real estate? Yes. –eric]

    Comment by frankhillis — 27 Mar 2006 @ 12:26 AM

  15. Seems like a pretty intelligent site. I have two questions. 1. Is there anything to the idea that an ice age could be created by scuttling a handful of ships loaded with iron filings in the Pacific Ocean? And 2. Regarding the calculations of how much we can expect sea levels to rise…do the calculations count only on the amount of water that derives from melting ice, or do the calculations also include the increased volume of seawater that comes from expansion due simply to heating of the oceans?
    And I guess a third incidental question: what are the relative contributions of melt water and heating expansion?

    [The answers are NO, YES, and Thermal expansion is estimated to account for about 1/2 of the total. Recent work has updated this number I believe but I’ll have to look it up. The 2001 IPCC estimtes for the various contributions of various sources is shown in the graph, here –eric]

    Thank you.

    Comment by David Howell — 27 Mar 2006 @ 1:26 AM

  16. Are ice dynamics models able to recreate the rate of sea level rise during meltwater pulse 1A yet? If the answer is still no, then I suggest that we have no idea how fast sea level rise might go in the next century…

    [Response: This is a fair point. There is no question that ice dynamics models are still in their infancy. However, it is not entirely relevant whether we understand happened in 1A because we are severely data limited. In contrast, we are quickly gathering a lot of data on the present state of glaciers and ice sheets. eric]

    Comment by Stuart Staniford — 27 Mar 2006 @ 1:43 AM

  17. I have watched the climate debate for more than 25yrs and I think the science has at last asserted itself over the politics ( even GWB agrees with the basic facts ). One of the side-effects of this “battle” is that the accepted science (IPCC) (looks like) it has underestimated the speed of the change. Maybe this a result of being extra conservative in order to fend off financially motivated and politically powerfull critics. Regardless of accuracy, I would like to congratulate all the scientists involved for defending and promoting the “republic of science” against the worst odds.

    A lot of attention has been given to sea level rises because of the direct and somewhat predictable affect on major cities. Theoretically if we can predict the extent of sea level change then we can plan our way around it without getting our feet wet.

    What bothers me is that a rapidly rising ocean is only the most visable symptom of a planet with a fever. The “birds and bees” are out of sync with each other already. If “the climate” was shifting ( say ) twice as rapidly as predicted by the IPCC, what is the likelthood of “symptoms” such as wide spread crop failures, disrupted fisheries, pasture into dust?

    Comment by Alan — 27 Mar 2006 @ 4:29 AM

  18. Re #17. Once again people want to know the effects that climate change will have on their the environment in real terms but this is not necessarily the job of climate science to do that as making such predictions can be scientifically damaging to ones career as it does not have a scientific basis.

    Generally Science leaves the fortune telling to environmental groups and the like and it is this naming of scientific literature by environmentalists that seem to land science in hot water although I believe that Jim Hansen of NASA has stated that human kind could have as little as 10 years to avert serious climate change.

    Comment by pete best — 27 Mar 2006 @ 6:06 AM

  19. How do you get paleoclimate data for an area that has been under ice for most of the past 100,000 years?

    [Response:Drill! See The Greenland Ice Cores –eric]

    Comment by C. W. Magee — 27 Mar 2006 @ 6:54 AM

  20. Would you comment on the Davis et al study published in Science since i gives a little perspective to the Velicogna and Wahl article.

    [Response: To which article are you referring? -eric]

    Comment by James Doggart — 27 Mar 2006 @ 8:25 AM

  21. “Flood Maps” mashes up NASA elevation data and Google Maps, and offers a zoomable localized visualization of the effects.

    Comment by Stephen Balbach — 27 Mar 2006 @ 12:48 PM

  22. Re No. 14 and Eric’s response to that post.

    Thanks to you for raising the chief question that I had which was “OK, Greenland and Antarctic ice are apparently declining more quickly that we once thought, but what does that translate into in terms of projected sea-level rise by 2100, provided the trends continue. I took a quick peek back at figure 11.12 referenced in Post No. 2 (the IPCC 2001 multi-scenario by AOGCM projections). Eric, these projections suggest a range of up to about 0.7 meters (2 feet) of SLR by 2100 for the A1Fi which is a rapid growth and fossil fuel intensive emission scenario. Even the most extreme combination does not yield 3 feet.

    I have three follow up questions (1) Eric, where does your estimate of 0.5 to 3 ft come from? (2) Can anyone comment on the current IPCC Fourth Assessment Report SLR projections and (3) Can the recent findings reported in Science be translated into a specific amount of increase in SLR projected for 2001? I note that Overpeck did not try to answer question 3 . . . I have not yet seen Kerr’s article.

    Comment by Tom — 27 Mar 2006 @ 2:04 PM

  23. Hi

    In the fijian news is a mention that sea level there has risen 8 cm in 13 years. That makes it 6 mm / year. Article indicates that also normal variability has some effect on this but web story is rather short on that and there is no link to in the news piece for the actual study as far as I can see.

    Comment by Seppo Syrjälä — 27 Mar 2006 @ 2:16 PM

  24. re #17 and #18. Alan has a valid point. There is lots of science regards species extinction and this may be the most salient aspect of environmental degradation, including AGW. There was a fine paper by Thomas et al. in Nature in the fall of 2004 suggesting that species extinction could be between 17 and 35% by 2050 based on mid range AGW models from the third IPCC report. Maybe Realclimate could host a guest post from a biologist on this impact. Humans need the services of coral reefs, fungus, ground hogs, pollinators, ocean fisheries, forests, and plankton to survive. Maybe we don’t need polar bears and seals, but what kills them can’t be too good for us. I think this is science.

    Comment by Tony Noerpel — 27 Mar 2006 @ 2:21 PM

  25. Re 18:

    I would disagree with you about scientists being generally cautious and environmentalists getting them into trouble by doing their own ‘fortune-telling’. The most detailed climate impact forecasts I have ever heard come from the Hadley Centre – those are the only forecasts that could conceivably remind you of ‘fortune-telling’ (particularly the way they are consistently reported by the media with absolute certainty!) They put information to the public about likely rainfall changes (with exact percentage changes) between now and 2050 or 2080 in different regions within the UK. I presume that they really want to bring home the reality of what the most likely result of climate modelling will mean for people – they want people to understand that climate change is and will be real. I sometimes worry whether such precise forecasts could be dangerous – I have seen one Guardian science editor claiming that the current drought cannot be linked to climate change because climate change will make the UK’s winters wetter (I understand that is only the most likely scenario, and if we cannot say for certain that a record-breaking drought is linked to GW then at least we know that those droughts are becoming more common globally because of GW and we cannot rule out a link with the one in the south of England just now – at least that’s my understanding).

    In the UK many of the main environmental NGOs tend to be far more cautious than, say, the Avoiding Dangerous Climate Change conference last year! There is widespread fear that we should not make it look too scary but should promote positive messages (not my own way of thinking – I think everybody just needs to be honest about what is known and what is not known for certain but is not ruled out, rather than worrying about how other people might react).

    Personally, I do think that it is important for scientists to explain their own understanding in simple enough terms for ordinary people to understand (this weblog of course does a great job at explaining complicated science to lay people!). And if James Hansen is extremely worried that sea level rises may become far more dramatic than models suggest that I am glad to know. It’s a matter of saying ‘I am worried, this could happen, and this is why I cannot rule it that it will happen’ – and those messages really can only come from experts, not (credibly) from environmentalists (other than by quoting experts).

    Comment by Almuth Ernsting — 27 Mar 2006 @ 2:55 PM

  26. This may be a reference to the same Hansen interview several recent posters have mentioned, saying they think Hansen said that modeling isn’t working – I haven’t found any original transcript or source, so I’m trying to figure out what he actually did say.

    Found at this advocacy page:

    Attributed to:
    Warm, Warmer, Warmest
    by Nicholas D. Kristof The New York Times 5 March 2006

    Part of the challenge in modeling climate is that we’re already off the charts with greenhouse gases like nitrous oxide, carbon dioxide and methane. “We’ve driven them out of the range that has existed for the last one million years,” noted James Hansen, NASA’s top climate expert. “And the climate has not fully responded to the changes that have already occurred.”
    End quote.

    Anyone got a first-hand source?

    [Response: His article in the Independent (reprinted here)
    He is specifically referring to ice sheet models, not GCMs. – gavin]

    Comment by Hank Roberts — 27 Mar 2006 @ 3:25 PM

  27. Hey folks – I thought you ought to know that Eric is the proud new father of a son. In 15 years from now, we’ll hear them arguing about whether 3-pin, randonnee or snowboarding is the best way to go ;-)

    [Response: No kid of mine will snowboard! -eric]

    [Response: You say that now… – gavin]

    Comment by Yann — 27 Mar 2006 @ 3:32 PM

  28. RE #25, it may get to the point once people are convinced that GW is real and dangerous, that people may overattribute all sorts of harms to GW, with the idea of letting science prove otherwise. (I’m a bit at that stage myself.)

    I was surprised to learn that sudden glacier movements in Greenland were causing local earthquakes. What next, GW causes or contributes to volcanos?? I’ll believe it, if scientists find it’s so.

    [Response: These “earthquakes” are just detectable seismic noise (detectable with sensitive instruments that is). Bedrock in Greenland is very old and stable, and nothing like what we normally mean by “earthquake” is likely to happen there. –eric]

    At long last yesterday ABC News started covering GW without using much of a pro-con format, though they did have George Will on This Week trot out “Scientists in the 70s were warning of an ice age,” and “it’ll cost trillions to combat GW.”

    Before yesterday major media nearly never covered GW, & when they did it was almost always in pro-con format (heavy on the skeptics for “balance”). Jim Leherer last year when speaking of GW (which is also rare on his Newhour), mentioned “GW, which SOME scientists say is happening…”

    Now ABC is wondering out loud why a huge portion the public think scientists are in big disagreement about whether or not GW is happening.

    Comment by Lynn Vincentnathan — 27 Mar 2006 @ 3:36 PM

  29. Re 25

    Science is nearly always cautious and never uses language such as the press would use to justify something. Scientific personnel may offer predictions of future conditions here on Earth based on models but this is the press labelling it as truth to the wider public rather than the scientists themselves prophesizing for they cannot do that and peer review finds people out.

    Comment by pete best — 27 Mar 2006 @ 4:08 PM

  30. Post 12. Coby how could you do that to me? The site is a disaster area.

    My offer still stands and if one sticks to basic and verifiable scientific principles one can go a long way with children/grandchildren – whom I may say are a very demanding audience.

    I see this site is now subject to AW too – not bad under the circumstances. Perhaps realclimate could set up a counselling service for all my aged and guilty friends and relatives.

    Comment by Eachran — 27 Mar 2006 @ 5:16 PM

  31. Another 40 cm? I recall that the ice in Patagonia and other locations different from Greenland and Antartica, if it were all to melt, would contribute 40 cm to the sea stand. So should we add another 30 cm or so to the guestimates given in earlier posts?

    Comment by David B. Benson — 27 Mar 2006 @ 5:23 PM

  32. David:
    I’m not sure where you got 40 cm from. If you got it by multiplying 0.4 mm/year by 100 years to get 40 cm, be aware that the 0.4 mm/year mentioned in the article is from Antarctia alone; it doesn’t include Greenland, or Patagonia, etc. Also, the melting of Antarctia’s ice sheets is unlikely to be linear. I believe it is expected to accelerate. If you got the 40 cm from elsewhere, I’m afraid I’m not much help …

    Comment by llewelly — 27 Mar 2006 @ 6:55 PM

  33. In post #14, in the response section, eric states:

    “”Sea level is going to rise somewhere between 1/2 and three feet in the next century or so. It could be much much more (say, two times as much).””

    So….it could be 6 inches, it could be 3 feet, or heck, even 6 feet. Is this not a case of “covering one’s bases” no matter what the outcome is?
    Such wildly divergent predictions seem to highlight the huge uncertainties in the science of AGW, not strengthen it.

    [Response:Gee, you’re right. I guess all this science is just hogwash, eh? Next time my doctor tells me, “well, you have a malignant tumor, but it may or may not become more serious,” I’ll decide that all doctors are charlatans and stop using their services. –eric]

    Comment by Paul — 27 Mar 2006 @ 7:02 PM

  34. Re #31, #32: I recall the figure of 40 cm from T.M. Cronin’s “Principles of Paleoclimatology”. To repeat, this was his figure for the sea stand rise due to complete melting of all ice other than Greenland and Antarctica.

    Comment by David B. Benson — 27 Mar 2006 @ 7:03 PM

  35. Re 32 (me) oops, sorry, Please ignore my post. It contains bad, bad math; 0.4 mm/year by 100 years would be 40 mm, not 40 cm.

    Comment by llewelly — 27 Mar 2006 @ 7:04 PM

  36. Does increased melting mean an increased chance of slowing the Thermohaline circulation? Wouldn’t that have the effect of cooling the SE Greenland/Iceland area of the N. Atlantic? Is it possible to model the fastest allowable rate of melting that can happen before this negative feedback occurs?

    Comment by C. W. Magee — 27 Mar 2006 @ 7:06 PM

  37. Re #27 “Hey folks – I thought you ought to know that Eric is the proud new father of a son.”

    Congratulations to Eric.


    Comment by Barton Paul Levenson — 27 Mar 2006 @ 7:43 PM

  38. Yes, congrats, Eric!

    Comment by Lynn Vincentnathan — 27 Mar 2006 @ 8:57 PM

  39. C. W. Magee, you might find this RC article helpful, particularly Stefan’s response to comment 4.

    Comment by llewelly — 27 Mar 2006 @ 9:38 PM

  40. Re: #8 & #9: Thank you, Gavin Schmidt and David Benson — points taken. So, additional facts point to a scenario something like that posited by W. F. Ruddiman of U VA, wherein orbital obliquity-driven cooling caused by declining insolation and augmented by decreasing CH4 is reversed by agriculturally induced CO2 and CH4 emissions, beginning as much as 8000 years ago. We apparently over-shot the mark in this industrial age, and now the Earth is over-heating. The situation is delicate — Too little GHG and we slip down that long, cold slope into glaciation; too much, and we lose the Everglades, Bangladesh, etc. Can we engineer our way out of this box? (Ref: “The Anthropogenic Greenhouse Era Began Thousands of Years Ago”; W.F. Ruddiman, Climatic Change 61: 261-293, 2003)

    Comment by Robert Beck — 27 Mar 2006 @ 9:45 PM

  41. This really is fantastic news! All that land currently buried beneath ice will become usable again. A vastly greater area than will be covered up by the rising sea-levels. So much more of the planet will have a comfortable climate.

    I guess the only risk to this wonderful scenario is that the fossil fuels run out sooner than anticipated and the greenhouse gases fall back into line. I am keeping my fingers crossed that that won’t happen.

    Comment by Anonymous — 27 Mar 2006 @ 10:27 PM

  42. Re: #41, “This really is fantastic news! All that land currently buried beneath ice will become usable again. A vastly greater area than will be covered up by the rising sea-levels. So much more of the planet will have a comfortable climate.

    I guess the only risk to this wonderful scenario is that the fossil fuels run out sooner than anticipated and the greenhouse gases fall back into line. I am keeping my fingers crossed that that won’t happen.”


    Comment by Stephen Berg — 27 Mar 2006 @ 10:44 PM

  43. Look for comments by Matt; if he gets his web page together, you’ll want to visit.

    Comment by Hank Roberts — 27 Mar 2006 @ 10:48 PM

  44. It is a shame the ice on Antarctica is so thick and at such high altitude, so that even with warming we won’t see the land mass of Antarctica for an awful long time, if ever. Is there anything that can be done about that? Drill lots of holes?

    Comment by Anonymous — 27 Mar 2006 @ 10:54 PM

  45. Re #42: Start buying real estate in Greenland now! Let us know how your investment goes!
    Plan carefully though. Past deglaciations have involved a bit of flooding here and there.

    Comment by llewelly — 27 Mar 2006 @ 11:26 PM

  46. RE 41, 44:

    See, sarcasm might not always work here, ’cause when glaciers retreat, there is not much organic matter or critters an’ stuff in the soil, hence it’s not arable.

    So, some folks take it literally and might not take the statements for what they are: just short of comedy. You are trying a comedy routine, right?



    Comment by Dano — 27 Mar 2006 @ 11:54 PM

  47. Hello:

    My speciality is information science, but I wanted to air an idea (or theory) in this arena. I have theorized that the Earth is akin to a giant capacitor in a closed circuit whose past climatic conditions were the result of the amount of oil underground. Simular to an oil filled capacitor in a closed circuit. Thank heaven for the dinosuars and species extinction! If my theories are at all correct, things will continue to worsten.

    Today, we are having a major impact on lowering those natural oil levels. It’s causing the Earth to loose its natural capacitance. Some have theorized a natural shift of magnetic poles may occur. But what if this purposed failure, or weakening, of the magnetized poles isn’t natural? What if the event is a natural response to the Earth’s loss of capacitance? What happens to a closed circuit when it’s oil-filled capacitor fails? My theory has many societal ramifications.

    I’m working on a basic Earth model incorporating my theories, but this will take time since there is a lot of data to simulate. I welcome input from you all.


    Comment by A.P. Storm — 28 Mar 2006 @ 12:44 AM

  48. Goodness, some rather bizarre comments here. It’s not easy being a scientist. What many non-scientists don’t seem to quite understand is that uncertainty is, and always has been, a huge part of science. So much of what we take for granted in scientific knowledge and advancement only arose out of an ocean of uncertainty just as large as the uncertainty with which we are trying to struggle with global warming. A good (ethical) scientist will admit this and, as far as he or she is able, explain the limits of his or her knowledge, only a charlatan will seek to create certainty out of incomplete knowledge or data, and only a charlatan will seek to exploit this uncertaintly for their own ends. We see to 2100 with no more clarity than H G Wells for instance could see the year 2000.

    But that does not excuse us from ignoring what we can clearly see now. For humanity, I think it is now pretty easy. Anthropogenic global warming is a proven fact beyond any kind of reasonable doubt. The quality and quantity of change is under some debate, but as every year passes the warnings from the scientists are becoming more dire. As the whole 6 billions of humanity arose and throve in the climate we now have, which has remained pretty constant for the last 8 thousand years, no-one can then greet some new climate as anything other than the most dire threat to everyone’s existence. There is now a moral or ethical obligation to accept this on behalf of our future generations, every single other consideration is now of secondary importance – politics, economics, cost, comfort, convenience, social inertia, what you will. It will require an effort on behalf of mankind equivalent to fighting the Second World War, except this time no one has to die, be maimed or psychologically scarred for their whole life, nor do cities have to be destroyed or civilisations wrecked. We cannot leave this to people who seek to weigh the health of the world against these other considerations, there is no set of scales that can accomplish this measurement. But until we fully understand this moral imperative, the necessary action to deal with this issue will never, ever come. Sermon over.

    Comment by John Monro — 28 Mar 2006 @ 1:53 AM

  49. Sorry for a frivolous question, but very recently I was reading a post on some now-forgotten science blog about the accelerating melting of the Greenland ice sheet — and they either linked to or published a beautiful picture of a waterfall of runnoff falling from an ice shelf on Greenland with some people standing along the banks of the rivulet at the top of the fall.

    Does anyone remember this and have a link for me? Thanks!

    Comment by KC Jones — 28 Mar 2006 @ 2:26 AM

  50. I think the photo you’re referring to is courtesy of Roger Braithwaite and was a cover of Science magazine 12, July 2002. See

    Comment by M. Chandler — 28 Mar 2006 @ 4:14 AM

  51. Re 46: Closest I can find is everyone’s favorite moulin shot . (it’s the pic on the right – click to enlarge). It looks like a waterfall, and there are people around it, and it was taken on Greenland’s ice sheet. But not on an ice shelf, and not precisely a waterfall…

    Comment by llewelly — 28 Mar 2006 @ 5:43 AM

  52. Re #18

    I don’t understand your apparent grudge against environmentalists. How does “naming of scientific literature by environmentalists”, land the authour in “hot water”, would you rather they sourced the forest fairies?

    If the ultimate “job” of climate science is to predict climate, and you are willing to give weight to Jim Hansen’s timescale for averting climate change, why does investigating the environmantal impacts suddenly become a “fortune telling” exercise? ( Note: To the vast majority of punters and journalists who do not understand the scientific method, the difference between scientists and soothsayers is based on an individuals notion of common-sense. )

    I will whole-heartedly agree that we do not have the ability to predict next years global harvest but ever since humans started planting seeds and milking cows we have come up with more accurate and better educated “guesses”. One thing has not changed in 10,000yrs of agriculture, when our “guess” is seriously wrong, civilization goes out the window and we starve.

    Turning a deaf ear to environmental groups is just as foolhardy as turning a deaf ear to fossil fuel advocates. Both groups have their dogma and both groups make plenty of dramatic assertions that have been investigated in a scientific manner. Doesn’t science itself progress by constantly finding ways to test the validity of popular, interesting, crazy, politically suicidal, blasphemous, scientific,,,assertions?

    Put another way, the concept of black holes floating around in the cosmos started with a geologist in 1783, it took at least 200yrs before anyone took the idea seriously and another 100yrs for us to find one!

    Comment by Alan — 28 Mar 2006 @ 5:43 AM

  53. Re 40.
    I thought that the agricultural CO2 theory had been disproved by Broecker’s demonstration of no -d13C anomaly prior to the industrial revolution.

    Comment by C. W. Magee — 28 Mar 2006 @ 6:49 AM

  54. I would like to know your views, after having watching the recent BBC programme on the slowing and potentional ceasing/reversing of the gulf stream, what kind of effect this would have on the rising sea levels? Surely this would reverse the melting of the ice-caps, as it would encourage a new ice-age. All be it in a 100 years or so. What can we possibly expect to happen? As this would effectively give us a greater area of ice-cap, forming along the length of the British Isles and pack-ice around our own coast-line.

    [Response: Absolute cooling is extremely unlikely, a new ice age an impossibility, and very little impact on global sea level. See – gavin]

    [It is further worth noting that the particular modeling experiments discussed in this post find that while Greenland meltwater does slightly affect the ocean circulation, even the very high rates of melting are insufficient to cause any cooling; at the most, they slow down the local rate of warming a little bit. Of course, more extreme scenarios can be imagined, with the glaciers accelerating even more. Since many of the important details of glacier dynamics are not well represented in the models yet, this can’t exactly be ruled out on the basis of these experiments. But this is all very much in the realm of speculation. The likelihood of a new ice age as a consequence of global warming has been grossly exaggerated in both the popular media and the scientific literature. –eric]

    [Response: Eric, do you have any examples for the latter?
    Concerning sea level impacts, a paper on this is here. -stefan]

    Comment by A Lincoln — 28 Mar 2006 @ 7:12 AM

  55. Re #18

    Environmentalists are potentially alarmist as they are in the world of politics and part of the free for all system of hype and hyperbole. It is not necessarily their fault, only hype gets peoples attention in the modern world, the press live and thrive on it. Science on the other hand cannot act that way and does not follow that method. Therefore scientists including Jim Hansen when they say things other than what they actually know are in the realm of speculation and conjecture even if it could end up being right.

    Contrary to popular scientific belief no black hole has ever been found. What has been shown is that taking relativity as gospel black holes can exist and may even exist but as yet none has been verified to exist. what has been shown is areas of space with massive gravitational strength but these could be one of a number of things and not necessarily a black hole.

    Climate science is complex and requires many variables in order to be able to predict second and third order effects such as the thermohaline systems faltering or the amazon drying out and releasing massive amounts of CO2. None is proven or has been shown to actually happen so we wait and try and predict with greater accuracy.

    Real climate is showing me personally just how complex climate is and we see very little here in the way of predicting or prophesizing doom and destruction for humanity.

    I sometimes wonder about the term “Abrupt” or “sudden” climate change as climate even under our deluge or fossil fuel burning is taking a long time to change (by human terms)radically enough to worry anyone in Government. Makes me wonder if there is a major scientific basis (younger dryas maybe but the cause is currently unknown)for it or is it a political tool.

    Comment by pete best — 28 Mar 2006 @ 10:49 AM

  56. #Re 54 Eric

    Does this mean that the thermohaline system in not in any present danger of stuttering or faltering at the present or near future time. Russian rivers increased discharge inot the atlantic, increased arctic ice melt and increased salinity and evaporation at the equator marked by increased freshness and precipitation at the poles which is increasing the flow rate of the thermohaline system (or so I have read) is not leading to issue with it at the present time and the recent measurements that showed a 1/3 slowdown in the flow rate were contentious at best ?

    Comment by pete best — 28 Mar 2006 @ 11:08 AM

  57. Thanks Chandler and llewelly, that’s the image I was after — the version in particular. Awesome image.

    Comment by KC Jones — 28 Mar 2006 @ 2:26 PM

  58. Post #48 by John Monro:
    ===It will require an effort on behalf of mankind equivalent to fighting the Second World War, except this time no one has to die, be maimed or psychologically scarred for their whole life, nor do cities have to be destroyed or civilisations wrecked. We cannot leave this to people who seek to weigh the health of the world against these other considerations, there is no set of scales that can accomplish this measurement. But until we fully understand this moral imperative, the necessary action to deal with this issue will never, ever come. Sermon over.===

    That wasn’t a sermon John, but an example of Churchillian oration.
    Still, addressing AGW, just like any other issue, remains in the realm of public policy which requires the assent and support of the general public.

    And combatting AGW must we weighed against other considerations. The sacrifices that scientists are proposing are so radical, so drastic, and so costly that only the public can decide if it is a truly worthwhile battle.

    Comment by Paul — 28 Mar 2006 @ 3:57 PM

  59. Re 58 Here is a sermon, or at least the views of the Archbishop of Canterbury, head of the Anglian Church.

    “And yet unless there’s a real change in attitude we have to contemplate those very unwelcome possibilities if we want the global economy not to collapse and millions, billions of people to die”.


    Paul, I wonder whether you think saving billions of lives is a “truly worthwhile battle.”?

    Cheers, Alastair.

    Comment by Alastair McDonald — 28 Mar 2006 @ 4:12 PM

  60. Re #48 & #58: Regional climate change?

    Quotes from “Forest insects at epidemic levels”, Associated Press:
    COUR D’ALENE, Idaho — THe region’s largest infestation of mountain pine beetles in 20 years has hit more than a million acres of forests in northern Idaho and Montana, while 2.5 million acres in Washington face desease and insect problems. … But she said it would take several years of normal moisture for forests to return to health. … Mountain pine beetles have also been a problem in British Columbia, where at least 20 million acres of forest have been killed. Officials there say warmer-than-average winters have led to the outbreak.

    Comment by David B. Benson — 28 Mar 2006 @ 4:15 PM

  61. Re 60: So, yet another positive feedback! We also have them beetles here in Bavaria. Spruce monocultures dying off.
    Re 58: O the immense sacrifices…
    Here´s a low-tech solution I currently ponder: Produce terra preta. Not slash&burn but slash&char them forests! Bury half of the char coal (=carbon sequestration plus valuable soil production), burn other half for energy plus refinery of the oils & methanol you get from wood pyrolysis.

    What do you experts think about that?

    Comment by Florifulgurator — 28 Mar 2006 @ 5:25 PM

  62. RE #58, AGW is not only a public realm issue, but ultimately a private realm issue. Each person has to decide whether or not to abate GW in his/her home, workplace, school, etc. As Hunter Lovins put it, “The national energy policy comes down to the cracks around your windows.”

    Since we in the rich world can actually save a lot of money, while saving the earth (I’ve reduced by more than 3/4 cost-effectively & save $100s every year), this should be a no-brainer. When will people reach down to pick up those $100 bills for their meager efforts at energy/resource efficiency/conservation? Are we so rich, gluttonous, and evil, that we would rather lose money & in the process kill people?

    But, of course, it is also a public issue at every level, from one’s town, state, country, & the world. It has to be addressed at all levels.

    Comment by Lynn Vincentnathan — 28 Mar 2006 @ 5:49 PM

  63. Re. 55:

    Contrary to popular scientific belief no black hole has ever been found. What has been shown is that taking relativity as gospel black holes can exist and may even exist but as yet none has been verified to exist. what has been shown is areas of space with massive gravitational strength but these could be one of a number of things and not necessarily a black hole.

    The theory behind black holes does a pretty good job of explaining what we see going on in the cosmos. Sure, the theory could be wrong – but until something better comes along, I’ll stick with black holes (If you’re aware of something that I’m not, please let me know).

    AGW does a pretty good job of explaining what’s happening to the planet. And until I see a credible alternative theory, I’ll stick with that as well.

    Falling into a black hole would provide some proof that it exists, but it would be pretty terminal for the observer. I don’t really want to take that chance with climate change.

    Comment by Stewart Argo — 28 Mar 2006 @ 7:10 PM

  64. Hosts, forgive the digression; Stewart, try this theory.

    Recent cite:

    Snippet from old 2001 news item:
    “… Emil Mottola of the Los Alamos National Laboratory in New Mexico and Pawel Mazur of the University of South Carolina in Columbia think gravastars are cold, dense shells supported by a springy, weird space inside. They’d look like black holes, lit only by the material raining down onto them from outside. In fact, they seem to fit all the observational evidence for the existence of black holes….”

    Comment by Hank Roberts — 28 Mar 2006 @ 7:39 PM

  65. Eric, I’m a bit confused about the magnitude of these icequakes in Greenland. You describe them as microquakes, and seem to view them as pretty insignificant, but news reports claim they are as big as magnitude 5 on the Richter scale. What’s the story? Are earthquake and icequake magnitudes incommensurate? Are the news reports wrong? I’ve been in magnitude 5 quakes, and I wouldn’t call them micro – just ask my dry cleaner.

    Comment by S Molnar — 28 Mar 2006 @ 10:03 PM

  66. Based on monitoring these on Taku Glacier in Alaska most ice quakes are truly microquakes. In a glacier with a high velocity they occur very frequently. They can be caused by 1. Basal sliding events, which have a low frequency a short duration and no glacier surface signal. Calving events which are also low frequency, short duration but due have surface waves near the glacier front and the scariest when standing on a glacier nearby the source are surface crevassing events which are low frequency, short duration and provide a surface wave very close to the event on the glacier. Only a basal sliding event will trigger a seismic wave in bedrock.

    Comment by Mauri Pelto — 28 Mar 2006 @ 11:19 PM

  67. Famous modeller: “I wouldn’t want to fly in a modelled airplane. I’d worry to much about what was left out”.

    Of course, this doesn’t mean that models are worthless! There are always uncertainties in a science where the experimental options are extremely limited or non-existent. The papers described above seem to have taken the best possible approach in that they compare their models to a historical record; and of course a historical record is going to have more uncertainties then a real-time experimental observation.

    So, take the above estimate of 0.5 to 3 ft of water (all over the surface of the Earth’s oceans). Add a warmer ocean. Send a tropical disturbance out from Africa towards Florida. Do this enough times and eventually Miami get flattened – direct hit by a full-strength category 5. So, yes, there is cause for concern. There might be even more cause for concern since we are heading into a CO2 regime that hasn’t existed for millions of years, according to the detailed, peer-reviewed and published work of hundreds or thousands of full-time scientists.

    Note: Biofuels are a good idea. Building a coal-fired ethanol plant, on the other hand… no comment.

    Comment by Ike Solem — 29 Mar 2006 @ 12:03 AM

  68. Re 63

    There have been recently some alternatives put forward to the notion of black holes but all present cosmology indicates that they do exist and are real cosmic phenomena.

    Global Warming is at present best explained by human induced fossil fuel burning but it is the consequences of that burning that concern me. I believe it to be true also but what we are discussing here is the environmental consequences and ramifications of that burning. At present according to the Keeling curve we are increasing the amount of CO2 in the troposphere by 2 ppm per annum. So by around 2040/50 we will have reached some 450 ppm and by 2100 it will be around 550 ppm. A doubling of pre industrial CO2 might happen and I personally believe that it will cause us a lot of issues but what those issues are are the issue.

    Is the Amazon going to dry out for instance, can it be shown to definitely be so ? Will the THC slowdown or become severely disrupted thus plunging Europe into colder and more frequently so winters ? Will rainfall change, will sea levels rise significantly ? Or will we just experience warmer weather and less and more rainfall depending on where we live.

    Indeed do we even have enough fossil fuels to make 550 ppm, we have plenty of coal but Oil and Gas are both getting towards their peak and alternatives need to be found before we experience an energy and transport crisis.

    For me at the present time the climate scientists are being ultra cautious and tell us that climate change is occuring, that it is human made but leave the impact of it to others to say and that makes for some extremely wild cliams to my mind anyway.

    Comment by pete best — 29 Mar 2006 @ 3:29 AM

  69. Re: #55 #63 #64 Off Topic, black holes DO exist…

    Quoting from the wiki link in my post…

    One of several definitions, I am using the general one…

    “The gravitational field is so strong that the escape velocity past its event horizon exceeds the speed of light.”

    And this is what I meant in the original post by the term “find one”…

    “…our own Milky Way. Sagittarius A* is now generally agreed to be the location of a supermassive black hole at the centre of the Milky Way galaxy. The orbits of stars within a few AU of Sagittarius A* rule out any object other than a black hole at the centre of the Milky Way assuming the current standard laws of physics are correct.”

    As we currently understand physics, what is inside the hole can never been seen so we will never observe the internal workings, we can also never directly observe the event horizon. No matter what is inside that region of space at the center of our galaxy, it will be forever known as a “black hole”.

    Off course, extreme skeptics can always come back with, “I doubt therefore I maybe!”

    [Response: No more black holes please. -gavin]

    Comment by Alan — 29 Mar 2006 @ 4:47 AM

  70. What I am trying to suggest is that there are people say who want everyone to sit up and take notice of climate change in order to get it at the top of the political agenda, to sell newspapers and magazines, to get the ratings up on the TV etc and there is what people who are peer reviewed say. The media has a responsibility to whatever it wants to, Science owns it to itself.

    Every climate computer model that fortells of doom is picked up on by the political lot and told as if it is gospel and it will happen. The peer reviewed mob on the other hand tell us within their sphere of influence/expertise what is happenning such as CO2 levels rising and correlating that to rising global temperatures etc. But it is a big leap to suddenly link beetles ravaging forests in Canada to climate change of humans doing although personally I do believe this sort of thing is related to human induced climate change but lots of people do not as yet thought seemingly the holistic systemic nature of climate change does make for some wild claims it is also right in many ways.

    One burning question is the acidification of the Oceans via increased CO2 absorbtion. This sort of thing worries me as second order effects in the systemic view (GAIA) of Earth.

    Comment by pete best — 29 Mar 2006 @ 9:47 AM

  71. There’s the other side to the sea level rise issue — the glaciers that are melting that in part lead to such a rise. While sea rise is slow & we could get out of the way in time to save our lives, once, say, Himalayan glaciers are all melted that will put an estimated 40% of China and India at severe risk of no water for irrigation, and consequent famine. And that story is repeated around the world where people depend on the annual cycle of glacier melt & replenishing to feed their rivers (& fishing industries) and irrigation canals. That’s the big story on the other side of the sea rise coin.

    We’ve got to keep looking at the big picture & the whole picture.

    Comment by Lynn Vincentnathan — 29 Mar 2006 @ 10:23 AM

  72. Re 70:
    If I’m understanding you correctly then you are saying that there is no evidence as yet to link worrying responses of plants, insects and animals to climate change, and that the peer-reviewed evidence is more about atmospheric warming, sea level rises and ocean acidification. Okay, I don’t know if there are studies yet about beetle infestations in Montana. But there are a lot of peer-reviewed studies into phenology, species extinctions, insect behaviour, etc. I understand that they are not discussed here because the people runnign this blog are climate scientists and not ecologists or biologists. This does not make those reports unscientific – it just means that we are yet to get a good weblog where climate scientists and biologists and ecologists work together. Meantime, the many peer-reviewed findings about the biosphere responding to climate change are no less scientific for this!

    Comment by Almuth Ernsting — 29 Mar 2006 @ 11:47 AM

  73. Re #70 I personally believe that as the atmosphere warms so there will be knock on effects to earths other sub systems including those studied by ecology and the like and that they are as scientific as other empirical sciences it is just that often what I read and believe to be possible in the more popular media even the more scientific media ends up being mistaken, wrongly reported or just plain misguided.

    This site has proved many things to me and cautions us all not to rush to conclusions just because a respected magazine or TV program says so.

    Comment by pete best — 29 Mar 2006 @ 12:03 PM

  74. Regarding the applicability of these studies to future climate trends:

    Warmer than a Hot Tub: Atlantic Ocean Temperatures Much Higher in the Past

    This is the general reason why some people are saying that climate models which focus on the relatively recent geological past (ice age era) might be of limited use in predicting future climate trends. Not to say that these studies aren’t valuable in their own right in terms of benchmarking model performance.

    Comment by Ike Solem — 29 Mar 2006 @ 2:03 PM

  75. Ike, who are the “some people” — what’s your source for the opinion stated about models?
    The press report you link to is about the recent Woods Hole study of marine sediments deposited when CO2 was over 1000 ppm. The article then talks about methane feedbacks. Current models don’t incorporate methane feedbacks, last I recall.

    The “some people” seem to be casting doubt on the models by asking the question asked long ago of Charles Babbage:

    “‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’ I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.”

    Comment by Hank Roberts — 29 Mar 2006 @ 3:06 PM

  76. Changes in the timing of winter-spring streamflows in eastern North America, 1913-2002 . From the latest GRL. Related, but older, online material . Also related, but older, and about the western US .

    This snow-melt stuff isn’t really on topic for a thread about sea-level rise, but it does seem related to flooding, and to intensification of the hydrologic cycle, which keep coming here. Also, it’s more closely related to sea-level rise than black holes …

    Now, I have a question – does intensification of the hydrologic cycle play a role in glacier melting? If so, what role? (Ignore for the moment the relative paucity of glaciers in the aforementioned areas …)

    Comment by llewelly — 29 Mar 2006 @ 3:40 PM

  77. Re: #74-75,

    “Some people” are weasel-words often used by those on FOX News and by climate skeptics. It tries to inject questions and disagreements where there really aren’t any.

    [Response:Allow me to interject with a couple of points of clarificatoin.
    1) The link in #74 about warm Atlantic temperatures is about a time millions of years ago, when carbon dioxide levels in Earth’s atmosphere were higher than present. That web site actually says “researchers say they may be an indication that greenhouse gases could heat the oceans in the future much more than currently anticipated. The study suggests that climate models underestimate future warming.”
    2) I think it is fair to say that climate models which focus on the ice age might be of limited use in predicting future climate trends. In spite of the analogy made between the present and the Last Interglacial by the authors of the papers I’ve discusssed in this post, it is arguably a pretty weak analogy. The summertime insolation anomaly glacial-to-interglacial is something like 60 W/m2. That’s why the glaciers melt! Even at 1000 ppm, CO2 doesn’t provide that much forcing. –eric]

    [Response: I think the LGM is a somewhat better test for CO2 sensitivity than Eric implies, if used properly. To be sure, the summertime glacial to interglacial anomaly is 60 W/m**2, this is in the seasonal cycle, not the annual mean; the main response to this is in the NH, where the ice sheets are. The response to this seasonal anomaly is much attenuated in the tropics, and even more attenuated in the Southern Hemisphere. In the SH midlatitudes, the LGM cooling is mostly due to CO2 reduction amplified by cloud and water vapor and sea ice feedbacks — plus a wildcard for what you think interhemispheric ocean heat fluxes are doing. In this regard, the SH cooling at LGM time provides a pretty pure example of the sensitivity of temperature to a reduction of CO2. The main assumption one then needs to make is that the sensitivity to an increase in CO2 from an interglacial base state is similar to the sensitivity to a reduction from the same state. The largely unexplained nature of the ice-free Cretaceous hothouse climates does suggest, however, that there may be some things going on at the warm end that aren’t analogous to the glacial-interglacial transition. –raypierre]

    [Response: Well, the climate sensitivity estimate from the LGM data, discussed by Gavin in the previous post, is just out. As both the LGM climate and the CO2 doubling climate are simulated with the full model ensemble, this does not use the assumption that climate sensitivity is the same, going up to higher CO2 or down to lower CO2 levels. -stefan]

    Comment by Stephen Berg — 29 Mar 2006 @ 4:03 PM

  78. Well i have read lots here, and it’s nice to get a consensus of some scientific thought

    Sorry for bursting in as a newbie, but

    It seems that we (being a climatologist myself, although young) are predominantly stuck in our pidgeon holes looking for variable a to explain b etc

    What of the other environmentalists…phenological studies…how can people accept our fears when they are stuck in one percepted area of science…why cant we do some correlations with more fields of study…how can we combat politicians with agendas of (dare i go there)or corporations bent on profit or even the guy on the street that is worried but sees NO instruments of change

    This may seem out of context but who give a fat lying pancake if sea level/temp rise x.y or x.z I mean really
    it’s all looking worse and I am, in my youth, surprised at the distraction/cowering tactics to face the problem/TRUTH…The young didn’t create this, but are now perpetuating

    No, I see a perpetuation of greed and feigned ignorance, especially in the US leadership, and now with Chindia….give me reason for hope

    With my few climate studies as a youth in here in Canada, I know there are always complaints about not enough intergration or communication(or data!)between scientists (e.g the man that looks at the river and the man that looks at the sky, even though they may be atop one another)

    IMVHO opinion to survive now (bird flu?)…Lets all get togethor in the name of humanity.

    Sorry if this is spam, but it cuts to the heart
    I don’t want to give up personally on humanity and hope the planet ‘gives us’ what we have from ignorance or laziness now apparently deserve.
    (we need Q to force a trial again)

    Comment by Jason Burford — 29 Mar 2006 @ 9:32 PM

  79. Re: 71

    One of those places “around the world” is most of the western US. Up here in Seattle, we have a reputation for lots of rain, but in fact, the summer here is usually bone dry for 3-4 months. Most of the water supply during those months comes from snow melt in the Cascades, but if the snow line rises and rain starts melting it earlier, that could cause big problems here.

    Comment by Richard Wesley — 30 Mar 2006 @ 1:31 PM

  80. Stefan (Response, bottom of #78) thanks for the link to Schneider et al. “just out”- it’s a PDF file.

    Brief snip:
    ” … a close link exists between the simulated warming due to a doubling of CO2, and the cooling obtained for the LGM. Our results agree with recent studies that annual mean data-constraints from present day climate prove to not rule out climate sensitivities above the widely assumed sensitivity range of 1.5-4.5C(Houghton et al. 2001). Based on our inferred close relationship between past and future temperature evolution, our study suggests that paleo-climatic data can help to reduce uncertainty in future climate projections.
    “Our inferred uncertainty range for climate sensitivity, constrained by paleo-data, is 1.2-4.3C and thus almost identical to the IPCC estimate.”
    [and add one degree C at the top, says their next paragraph]

    Comment by Hank Roberts — 30 Mar 2006 @ 2:45 PM

  81. I’ve just been reading the above article when I noticed the following

    Finally, in a very nice bit of work Velicogna and Wahr use data from the “Gravity Recovery and Climate Experiment” (GRACE) satellites to show that the Antarctic ice sheet has been losing mass at a rate of 150 +/- 80 km3 each year since 2002.

    Is this correct? I mean the bit about “losing mass at a rate of 150 +/- 80 km3 each year since 2002”. Isn’t this rather a short period from which to be drawing any conclusions? Mind you I can see the advantages. No need to bother trawling through decades of data which can be a bit time-consuming. In fact, the more I think about it the more I like it – so much so I’ve even decided to do my own study.

    This study analyses land-based winter (Dec/Jan/Feb) temperatures in the Northern Hemisphere for the period 2001/02 to 2005/06. The data used in the study is from the GISS NH temperature record (that should keep everyone happy). OK …………….finished!

    Our results show that land-based NH winter temperatures have cooled by -0.028 deg C per year since 2001. If this trend continues NH winter temperatures will be -2.8 deg C (-5.0 deg F) below current levels within 100 years. The implications could be catastrophic. Snowfall levels in northern Europe may be up to lots more than they are at present.

    [that’s dealt with the “could bes”, “up tos”, & “may bes” – now we need to finish with the heart-tugger for the media]

    Mammals which are native to the high northern latitudes may be forced to migrate in order to escape the harsher conditions. Some scientists believe Santa Claus may be forced to relocate as far south as Scotland. In a worst case scenario, Father Christmas may well be speaking with a glaswegian accent within 150 years.

    [Response: Maybe if you just kept reading:

    It is also important to remember that the data showing accelerating mass loss in Antarctica and rapid glacier flow in Greenland only reflect a very few years of measurements — the GRACE satellite has only been in operation since 2002, so it provides only a snapshot of Antarctic mass changes. We don’t really know whether these observations reflect the long term trend.

    – gavin]

    Comment by John Finn — 31 Mar 2006 @ 6:36 AM

  82. “Unexpected warming in Antarctica”:

    “Winter air temperatures over Antarctica have risen by more than 2C in the last 30 years, a new study shows.

    Research published in the US journal Science says the warming is seen across the whole of the continent and much of the Southern Ocean.”

    Comment by Stephen Berg — 31 Mar 2006 @ 11:14 AM

  83. I recommend everyone look at what your local newspapers are printing about this subject in the past few days — this narrowly defined search found mine, sad to say:

    Write an editor — help stop the madness!

    [Response: Try clicking through. The original SF Gate article has actually been corrected and has had its title changed to ‘3 feet by 2100’ (down from 20!). Most of the other hits are pick ups of the original (mistakenly headlined) article. There is some hope! – gavin]

    Comment by Hank Roberts — 31 Mar 2006 @ 8:31 PM

  84. ===Post #83
    [Response: Try clicking through. The original SF Gate article has actually been corrected and has had its title changed to ‘3 feet by 2100’ (down from 20!). Most of the other hits are pick ups of the original (mistakenly headlined) article. There is some hope! – gavin]===

    Only the headline for the SF Gate article has been corrected. The actual article still states (four times)that there could be a 20 foot rise in sea level by 2100.

    Comment by Paul — 31 Mar 2006 @ 11:59 PM

  85. Why is the public so slow to respond to what is being reported concerning the rapidly changing climate? They are confused.

    Could the scientific community do anything to inspire public support for the needed changes? Yes.

    It is understandable that people are confused about changes in sea levels, melting ice and other results of global warming. For decades, the scientific community has used the phrases, â??present rate of changeâ?? and â??present rate of increaseâ?? when discussing continually changing projections. The rates are changing with every new discovery.

    The public is left believing that there are, in fact, great uncertainties in the conclusions and predictions of those in the scientific community. The great differences in recent reports on seal level changes bring this problem into better focus than other projections that seem to change over months or years of time. But, the variations in projected changes make skeptics of the people in the U.S.

    It is also understandable that modeled projections are based on presently observable rates. It would not be very scientific to base them on anything else. If the public is to be swayed, the reporting can not be left to environmental activists. They are not trusted by the people who need to make the greatest changes.

    There is now a critical need for an ambassador to assist the scientific community in its relations and communication with the rest of the world. The world needs to have a person with understanding of the science, a personable presentation and the respect of both the public and their peers. This person needs to present the uncertainties as what they are; the greatest reason of all to take action now.

    Then the scientific community needs to find a way to report its findings, based on present rates, but without giving the impression that they believe the rates will remain the same.

    Comment by Melvin Landers — 9 Apr 2006 @ 6:00 PM

  86. Cilmate Change and the Media, Reality and the Future
    We are of course deeply heartened by the sudden clamor over climate change. 2006 may just be the year in which climate change will finally…

    Trackback by WorldChanging: Another World Is Here — 10 Apr 2006 @ 7:44 PM

  87. Climate Change and the Media, Reality and the Future
    We are of course deeply heartened by the sudden clamor over climate change. 2006 may just be the year in which climate change will finally…

    Trackback by WorldChanging: Another World Is Here — 10 Apr 2006 @ 11:37 PM

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