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  1. You all correctly note that there is good degree of natural variability in the Greenland ice system:

    “We should be careful to point out though that this is only for one decade, and doesn’t prove anything about the longer term. As many of the studies make clear, there is a significant degree of interannual variability (related to the North Atlantic Oscillation, or the response to the cooling associated with Mt. Pinatubo) such that discerning longer term trends is hard.”

    I think it would be remiss not to also mention that longer-term variations in the Atlantic Multidecadal Oscillation (AMO)are likely impacting the current climate conditions in and around Greenland. There is a fine illustration (Figure 1) in Knight et al. (GRL, 2005) that shows this to be the case. Or, see the illustration from Goldenberg et al. (Science, 2001) reproduced here.

    [Response:I’m afraid that the idea that the AMO explains everything is pretty weak. Indeed, the evidence that the AMO is anything other than random noise (in constrast, for example, to ENSO), is pretty weak. In fact, the evidence that the AMO does anything is pretty weak. The AMO is a statistical description of climate phenomena. As far as I am aware, no one has made an even slightly compelling case that it is a physical phenomenon in and of itself, the way that ENSO is. Hence it is unpredictable, and very difficult to separate from other effects, like global warming. –eric]

    Comment by Chip Knappenberger — 2 Mar 2006 @ 11:33 AM

  2. Terrific post. Thanks for putting all the recent studies in context!

    Comment by Ana Unruh Cohen — 2 Mar 2006 @ 11:54 AM

  3. This recent research is extraordinarily valuable. Having worked on one of the accelerating glaciers, Jakobshavns Isbrae in West Greenland, it seems difficult to slow these glaciers down. Their momentum is such that it is hard to envision a quick slow down now that the velocities have increased. The acceleration should reduce basal and sidewall friction and promote a continuation of the current velocity without a notable change in a boundary condition.

    Comment by Mauri S. Pelto — 2 Mar 2006 @ 12:08 PM

  4. I gather that even if the acceleration were found to be caused by a greater snow load pressing down on it, that could also at least in part be attributed to GW, since we expect increased precip (incl. snow) in that region from GW.

    Or am I missing some point?

    Comment by Lynn Vincentnathan — 2 Mar 2006 @ 1:53 PM

  5. Very nice overview, but regarding your: “Unfortunately, the physics of basal lubrication and the importance of ice dynamics highlighted in the Rignot & Kanagaratnam results are very poorly understood and not fully accounted for in current ice sheet models.” This issue was dealt with only superfically in R&K by ref. to Zwally et al,2002. Surface melt-induced acceleration of Greenland ice-sheet flow. Science, 297(5579). Also, what R&K actually said is: “Current models used …. do not include such physical processes and hence do not account for the effect of glacier dynamics.” Inclusion of melt-acceleration was a central feature of the modelling by B. R. Parizek, R. Alley, Implications of Increased Greenland Surface Melt under Global-Warming Scenarios:Ice-Sheet Simulations, Quat. Sci. Rev. 23, 1013(2004), and most models do include glacier dynamics in some form.

    [Response: Thanks for the clarification. The point was to highlight the low level of understanding of that physics, not to imply that no-one had ever thought about it before. – gavin]

    [Let me also add (for the sake of our general readership) that it is not so much that the “physics are not well understood”, because we do of course know what is required to make glaciers speed up, or slow down. The problem is that without a detailed image of the bottom of the ice sheet (and I mean really detailed), we can’t possibly track all the intracies of water flow, basal water pressure, etc. Incorporating this kind of thing into models is something people are working on (Richard Alley among them), but is computationally very expensive and cannot yet routinely be done in 3-dimensional ice sheet modeling. –eric]

    Comment by Jay Zwally — 2 Mar 2006 @ 1:57 PM

  6. Here are Rignot’s presentation slides from the Fringe 2005 workshop:

    Comment by smyyga — 2 Mar 2006 @ 2:15 PM

  7. As it seems that there is quite a bit going on with modeling the ice dynamics, it would be nice to hear more about progress on that.

    It should also be noted that in the same issue as Rignot & Kanagartnam Science published a commentary by Julian Dowdewell synthesizing it and Johanessen et al, although I think the discussion was along the same lines as RC’s.

    Chip Knappenberger’s comment reminds me to also mention that the coal industry-funded World Climate Report (written by Chip and Pat Michaels) harshly criticized both R+K and the editors of Science based on the idea that R+K had ignored the results of J et al and that the editors were complicit in this lapse. In addition to the synthesis commentary I mentioned above, a quick fact check showed that the R+K paper was accepted for publication (i.e., was final) a few days before J et al was published, which is to say there’s a more than fair explanation for why the former didn’t cite the latter. In any case, as the RC post points out, R+K can hardly be accused of ducking the accumulation issue since they did discuss the results of Hanna et al. Drawing the obvious conclusion from all of this would get me into ad hom land, so I’ll leave it at that.

    Comment by Steve Bloom — 2 Mar 2006 @ 3:13 PM

  8. Re #3 (MSP): Mauri, could you provide more information on the point you made? Is there a paper? Also, wouldn’t the existence of such an effect tend to argue against any sort of direct synchronization of the acceleration with the rather short-period NAO?

    Comment by Steve Bloom — 2 Mar 2006 @ 3:18 PM

  9. This is speculative on my part as I am going to put 2 and 2 together here and suggest that if Greenland is not that significant then what is causing thermohaline slow down in the north atlantic ?

    I presume that someone is going to tell me that the thermohaline system is in fact fine and no slowdown has in fact been scientifically validated due to bad measurements and the like

    [Response: Yep. See here. – gavin]

    [Response: But, aside from that, melting Greenland is not the only way to change the freshwater balance of the North Atlantic. You can do that to some extent by changing sea ice transport (brine rejected where ice forms, fresh water put in where ice melts), and also by changes in the river runoff minus oceanic evaporation –raypierre]

    Comment by pete best — 2 Mar 2006 @ 4:15 PM

  10. Has your view that ‘thermohaline system is in fact fine…’ altered in the light of subsequent papers from Schlesingeret al. and the UK’s National Oceanography Centre?

    Comment by Ben Coombes — 2 Mar 2006 @ 5:37 PM

  11. Regarding #4 Lynne The acceleration is not due to a greater snow load. The snow load has been less near the margins of the ice sheet due to warm summers, and at this point the terminus region of the glacier has no idea what is happening near the center of the ice sheet. The response time of these large glaciers is too slow for the communication of a positive mass change of the the last 20 years to be communicated down the length of the glacier already. Reagrding #8 two recent papers examining this issue are Thomas, R. H. et al (2003)
    Investigation of surface melting and dynamic thinning on Jakobshavn Isbrae, Greenland. J
    Glaciology 49, 231-239.
    Thomas RH (2004), Force-perturbation analysis of recent thinning and acceleration of
    Jakobshavn Isbrae, Greenland, J Glaciology 50 (168): 57-66.
    These papers refer to other key papers as well.

    Comment by Mauri Pelto — 2 Mar 2006 @ 5:39 PM

  12. I want someone to explain to me then (if it is true of course) why tropical waters have become saltier and temperate waters fresher.

    I would like realclimate to run an article on how in fact the ocean and air and the process of evaporation and precipitation are causing this effect will more water vapour and less or more rain result from human kind climate change.

    Comment by pete best — 2 Mar 2006 @ 6:44 PM

  13. Surely if the density of ice is 0.917 g/cc, 1 km^3 of ice will have a mass of 0.917 Gt? I’m assuming that “Gt” is “gigatonnes”….

    [Response: Whoops. You are of course correct. I have updated the numbers. Thanks – gavin]

    Comment by Nick Barnes — 2 Mar 2006 @ 6:52 PM

  14. As discussed before in a few other topics, the retreat of Greenland glaciers started already a long time ago. For the largest one, the Ilulisat (Jacobshavn) glacier probably before 1850 (and according to another source, since the LIA, see Csatho ea., last paragraph).

    Unfortunately, we have no satellite measurements prior to the 1980’s, only aeral pictures which show a huge thinning of the glacier (70 m) in the early 1950’s. This thinning followed a very rapid retreat of the break-up point of the glacier in the period 1930-1950.

    As around Greenland’s edges, the summer temperatures probably are important for glacier dynamics (lubrication by melt water), it is interesting to note that the summer temperatures in the period 1930-1960 were as warm or warmer than after 2000. The 1970-1990 period was considerably colder all around Greenland. This seems to be AMO (more than NAO) bound. The comparison of the recent accelleration with the previous period of rapid melting/retreat is what I missed in the different papers about Greenland glaciers…

    As Mauri in #3 pointed out, at this moment, it seems impossible that the trend reverses, but as shown in the 1960-1990 period, there was some stabilising of the trend with cooler temperatures. But of course, if temperature stay high and/or increase further, the accelleration will go on…

    [Response: And as I mentioned the last time you used this argument, and in many other contexts on RealClimate, it is an utter fallacy to say that because X thing started happening in 1850, the continued happening of X thing today is due to whatever made X happen in 1850. This appealing and recurrent bit of nonsense comes up all the time for mountain glacier retreat, too. If you follow the fallacy to its conclusion, you’d have to conclude that, no matter what evidence you find today, you could never conclude that Greenland ice retreat had anything to do with CO2– even if the whole glacier melted and dumped itself in our proverbial laps. To be sure, until models get to the point where they can do a proper CO2 vs natural variability attribution study on Greenland (and Antarctica) we won’t have a good answer, but please its getting tedious hearing the old “X started in 1850” argument over and over again. –raypierre]

    Comment by Ferdinand Engelbeen — 2 Mar 2006 @ 7:48 PM

  15. Re: Thermohaline implications. Greenland melt isn’t the only source of extra freshwater for the North Atlantic. There’s also the extra river runoff due to increased precipitation over land and also decreased evapotranspiration due to the CO2 fertilisation effect on stomata.

    Comment by Timothy — 2 Mar 2006 @ 8:01 PM

  16. We put together an educational exercise that uses the GISS Model II (8×10) GCM to explore the potential impact of global warming on Greenland’s ice sheet. The idea for the exercise came about as a result of the Johannessen et al. (2005) paper and the interest it was generating amongst teachers we work with. In case some of you are interested here’s the link:

    For those interested in paleoclimate, I would also point out that during the last period in Earth’s history when the global temperatures were more than 2°C warmer than modern (mid-Pliocene, ca. 3 Myr ago) there is strong evidence that the Greenland and West Antarctic ice sheets were gone….how long that takes to occur is something we sure would like to know.

    Comment by Mark Chandler — 2 Mar 2006 @ 9:37 PM

  17. There is nothing , really nothing better than near live events as examples, such as North coast of Ellesmere Island Canada loaded with mountain and Fjord glaciers now having SAT’s +20-30 degrees C above normal. IR pics of Ellesmere shows it covered by what seems to be a huge very dark cloud,there are some, but a closer look merely demonstrates heat covering its huge landscape, totally a-typical, at this time of the year, Ellesmere would shine bright white, with -45 to -50 SAT’s instead of -9C , with imppecable clarity and contrast as seen from space with IR eyes. Further East, Greenland lost its IR white shine, greyish signatures is a norm on the ice cap during the last few winter years, while around its edges, darkness steep darkness.

    Comment by wayne davidson — 3 Mar 2006 @ 12:47 AM

  18. Re #17: Links to the site(s) with those pictures, Wayne?

    Comment by Steve Bloom — 3 Mar 2006 @ 3:21 AM

  19. Many thanks for this post. It is a continuation of its many excellent predecessors.

    There is no real excuse for anyone, reasonably intelligent and interested (and who in our present circumstances would not be interested?) not to know the basics in the climate science field and to have, strongly or weakly held opinions on public policy as a consequence.

    I have to say that I become just faintly depressed when I read of scientists (in The Guardian 28th Feb on some “leaks” from the next IPCC) talking about, say, a 95% chance of everything being all right. They should be invited to run a lottery on the following proposition – roll up, roll up for the last chance saloon : stake all you have on buying a ticket, you stand a 95% chance of not losing and getting your money back but a 5% chance of losing everything – and see how many tickets they sell!

    Comment by Eachran — 3 Mar 2006 @ 7:03 AM

  20. Regarding #14: Well put Raypierre. In fact I published a paper in 1989 on “The Equilibrium balance of the Jakobshavns Isbrae”. This was based on observations from 1950-1988 when observations had begun that the terminus was stable, the mass losses from melt and calving equalled the snowfall, and that velocity had been consistent. The glacier had achieved relative equilibrium with climate during this interval. Thus, to rouse the glacier from this state, as has happened, did take a significant warming. This point is echoed by the same stable and then accelerating mass balance response of other Greenland Outlet glaciers. Something is afoot in Greenland, it is not ordinary and it is triggered by warmer conditions.

    Comment by Mauri Pelto — 3 Mar 2006 @ 9:49 AM

  21. Re: the response to #14

    …but please its getting tedious hearing the old “X started in 1850” argument over and over again. –raypierre ]

    I disagree. This is one of a number of crucial (if inconvenient) observations which bring into question the extent of the role of CO2 in climate.

    Comment by John Finn — 3 Mar 2006 @ 11:07 AM

  22. Is it me or is according to climate scientists the average global temperature rising but it is having no preceptable effect on the planet ?

    Greenlands glaciers are fine, river water run off could be happenning anyway, thermohaline system is fine and if it is weakening then it is not necessarily down to human made climate change, antartica is fine and if it is melting its a natural cycle, drought happens anyway and weather system and hurricanes are not different then before human made climate change was detected.

    So what and where is the problem if human made climate change is not affecting anything ?

    Comment by Pete Best — 3 Mar 2006 @ 11:24 AM

  23. Eric,

    Thanks for your comment about the AMO in Comment #1.

    However, a quick check of my comment will show that I wrote that the AMO is “likley impacting the current climate conditions in and around Greenland.” I never said that it explained everything (although I supposed that it could).

    Anyway, since my description of the AMO impacts in the North Atlantic is along the lines of the Real Climate Glossary entry for AMO which reads:

    Atlantic Multidecadal Oscillation (“AMO”)

    A multidecadal (50-80 year timescale) pattern of North Atlantic ocean-atmosphere variability whose existence has been argued for based on statistical analyses of observational and proxy climate data, and coupled Atmosphere-Ocean General Circulation Model (“AOGCM”) simulations. This pattern is believed to describe some of the observed early 20th century (1920s-1930s) high-latitude Northern Hemisphere warming and some, but not all, of the high-latitude warming observed in the late 20th century. The term was introduced in a summary by Kerr (2000) of a study by Delworth and Mann (2000).

    perhaps you ought to confer with your other Real Climate colleagues and tone down the part about the AMO signal in the Arctic.

    What evidence do you have that the recent warming in the North Atlantic around Greenland is NOT part of the AMO phenomena? Knight et al. (and the RC Glossary) clearly suggest that it is, and even go as far as to predict its future behavior.

    Comment by Chip Knappenberger — 3 Mar 2006 @ 12:06 PM

  24. Re #14:

    The problem is that the largest retreat of the break-up point of the Ilulisat/Jacobshavn glacier was in the period 1930-1950, just before the more intensive observations. And about the equilibrium, I see some discrepancy with the observations of the begin fifties by Csatho ea.:

    This record shows two periods of rapid thinning by about 70 meters, in the early 1950s and since 1997. Observed changes in glacier behavior during these two events are markedly different. The recent thinning, which involved several episodes of retreat followed by large thinning, resulted in a rapid retreat of the calving front toward grounding line. Thinning in the 1950s occurred during a period when the calving front was stationary with only minor annual fluctuations. Nevertheless, aerial photographs collected in the 1940s and 50s indicate that thinning extended far inland.

    To be noted: the retreat of the break-up preceding the 1940/1950 thinning.

    Agreed that warmer conditions are at the base of the recent speed-up. But around Greenland summer temperatures after 2000 do not, or just reach 1930-1960 temperatures…
    Thus may I disagree, and IMHO the current Greenland glacier retreat (still) is within “normal” limits?

    Which doesn’t include that GHGs play no role at all, but in the Greenland temperatures/glacier retreat this is not (yet) detectable (opposite to the average worldwide glacier retreat, but that will be discussed in a next message in reaction to the comment by Raypierre).

    Comment by Ferdinand Engelbeen — 3 Mar 2006 @ 12:14 PM

  25. re 21 (JF):

    I disagree with your disagreement. Your argument presumes the same causation for the time period in question. You haven’t shown that to be true.



    Comment by Dano — 3 Mar 2006 @ 2:56 PM

  26. RE: #15. Consider the fact that there is drainage from the Canadian Shield’s array of slow moving surface waterways entering both the Arctic and Atlantic that is essentially relic water from the great melt. Consider also the damming of multiple north flowing rivers in Eurasia.

    General comment about this thread. Lots of energy going into explaining Greenland ice conditions in a way that tries to exclude / discredit naturally occuring oscillations. It is a mind set.

    Comment by Steve Sadlov — 3 Mar 2006 @ 3:11 PM

  27. How does the new finding that Antarctic is losing ice mass fit here? See:

    [Response: Quite possibly it doesn’t; see here – William]

    Wasn’t that one of Crichton’s arguments against GW, that the Antarctic was gaining ice mass? Or was it simple getting colder?

    Comment by Lynn Vincentnathan — 3 Mar 2006 @ 3:32 PM

  28. Re #4 – Again no proof but a statement “that could also at least in part be attributed to GW”.
    Do you have the temperature statistics for Greenland? Is it rising? the western Arctic may be, but is Greenland?
    Re #5, #11 and others – I do not see any proof that increased thickness is not causing some of the acceleration. Check the temperatures first.

    Comment by Gerald Machnee — 3 Mar 2006 @ 3:35 PM

  29. Re#27 It has been noted that the key accelerating glaciers have thinned considerably in the lower reach accompanying the retreat. Hence, there is not a thickenning of the lower reach of the glaciers that would influence velocity there. The change in ice thickness at the center of the ice sheet of less than a meter will hardly matter to an ice sheet that is generally over 1500 m thick. One can easily do the math on this to see the lack of potential influence. Also the response time of an outlet glacier to a climate change at its head is more than a couple of decades. However, changes at the terminus have an immediate impact on that area. Sadlov makes a good point about the lack of a detailed look in these papers at natural cycles, since they focus on such a short term data set. I will point that in a J of climate paper in 2002 by Jason Box, working with Greenland temperature records particularly near Jakobshavns, it is noted that from 1990-2001 a statistically significant warming of 2-4 C was observed in West Greenland which is statistically significant. It is also noted that the temperature record is highly correlated with NAO as one would expect. However, it the unusual degree of current warmth and melting that, leads me to suggest that this is stamped upon the existing natural trends accentuating the warm periods and dampening the cool periods.

    Comment by Mauri Pelto — 3 Mar 2006 @ 4:08 PM

  30. RE 25:

    Do you have a citation that some of the current drainage is as you say (whatever that means)? Thank you.

    Do you have a citation that the current Greenland ice conditions are due to naturally occurring oscillations? And what are those oscillations? Thank you.

    RE 27:

    Greenland’s temperatures are rising in some places, as Lynn implies. As Greenland is a large place, it is best to consider it not as a whole.



    Comment by Dano — 3 Mar 2006 @ 4:31 PM

  31. Re 25 “… in a way that tries to exclude / discredit naturally occuring oscillations. It is a mind set.”

    As written in the above article: “As many of the studies make clear, there is a significant degree of interannual variability (related to the North Atlantic Oscillation.”

    I for one, do not appreciate political statements in a scientific dialogue.

    The peer-reviewed literature is filled with studies on naturally occuring oscillations and all possible causes for climate change including naturally occuring oscillations.

    Comment by Richard Ordway — 3 Mar 2006 @ 5:02 PM

  32. RE:#29

    Mauri – You are obviously all over this stuff. But couldn’t there be a “hydraulic press” type effect going on? I agree that a 1/1500th gain in depth on the central ice sheet is not huge, but if the pressure were channeled narrowly towards an opening that then reached a glacier, couldn’t it have a dramatic effect?

    Comment by Tom Cecere — 3 Mar 2006 @ 5:32 PM

  33. Re #29,

    Mauri, all stations around Greenland (as far as still in use) show a recent warming, but most stations don’t or just reach the 1930-1960 summer temperatures.
    Specifically the station in Ilulisat/Jacobshavn (West-Greenland), had a significant increase of 4 degr.C in the period 1920-1930. But it ceased operation in 1980. The nearby Egedesminde station started operation around 1950 and parallels the Ilulisat station within a few tenths of a degree for the yearly averages in the overlapping period. It shows a 4-6 degr.C cooling in 1979-1993 and a 5 degr.C warming thereafter. The temperatures after 2000 just reach the temperatures in the 1930-1960 period of Ilulisat.
    The same for summer temperatures, where temperatures after 2000 just reach the 1950’s for Egedesminde, but here is an offset against Ilulisat, the latter shows average 2 degr.C higher summer temperatures in the overlapping period.

    Thus for Greenland as a whole and West-Greenland in particular, there is little difference in temperatures between today and 65-85 years ago.

    Btw, my comment in #24 was in reply to your comment #20…

    Comment by Ferdinand Engelbeen — 3 Mar 2006 @ 6:20 PM

  34. Re #14 (comment)

    Raypierre, if the speed-up/break-up point retreat of the Greenland glaciers now is less (for which we have evidence from the largest Greenland glacier) or similar to the 1930-1950 period, when CO2 levels were app. 25 ppmv higher than in the pre-industrial period, and current levels are 95 ppmv higher than in 1850, then one can safely conclude that natural forcing was responsible for most, if not all, of the speed-up in the period (pre-)1850 to 1950 and in part for the period 1990-current. The more that the relation of Greenland temperatures with the AMO/NAO, another natural phenomenon, is linked to the temperature decrease in the period 1960-1990 and the recent upswing. Further, as in many other climate responses, there is a short-term response of glaciers to temperature changes and a long-term, which may need several decades, even if temperatures stay steady after a change…

    About the influence of the CO2 increase on glaciers in general:
    The increase of CO2 in the period 1850-1950 was mainly by the use of coal (1-4% sulphur). SO2 emissions in that period were directly related to coal use (see e.g. the US figures), thus any effect of the 25 ppmv increase of CO2 on temperatures is (in part) countered by parallel increases of sulphate aerosols (this pleads against the huge influence of sulphate aerosols in the post-1945 period…). Thus the increase in global temperatures in the period 1850-1950 was mainly from natural variations (IMHO mainly solar, but internal oscillations may be involved too).

    Now back to the study of Oerlemans: This study shows that near all (extratropical) glaciers have their largest decrease in the period 1850-1950, but the average is relaxing after 1950, while the tropical glaciers are receding faster than ever. The latter seems not directly related to local/regional temperatures, but there is a trend to less clouds in the last decades in the tropics, which implies more direct sunlight (~2 W/m2) helping with the sublimation of ice fields.
    For mid-latitudes, clouds play less role in the radiation balance, but play an important role in precipitation.

    Thus in summary, there is little evidence for CO2 emissions influence on glacier retreat in the 1850-1950 period, and mixed evidence for an increased influence after 1950.

    Comment by Ferdinand Engelbeen — 3 Mar 2006 @ 6:42 PM

  35. Thanks for addressing the AMO. Anyone with experience with data handling knows you can apply time series analysis to any dataset and pull out ‘frequency modes’ that may or may not have anything to do with reality, even if you are working with an almost completely random dataset. These analysis are still valuable if they lead to a plausible mechanism or point towards an interesting phenomenon that may be buried under layers of other signals (such as El Nino, which does have a physical mechanism, if still under discussion whether it’s an atmospheric or oceanic driver). It’s worth noting in this context that the AMO was heavily played on a number of popular news shows as the cause of last year’s hurricane season. It looks like noone has a plausible mechanism of any kind for the AMO, however.

    Comment by Ike Solem — 3 Mar 2006 @ 8:15 PM

  36. With respect to #32 first. Most people tend to think of changes in glacier behavior being communicated from the head of the glacier to the terminus. However, in the recent glacier acceleration the acceleration is greatest at the terminus and is indetectable by the time you are 10% of the way to the head of the glacier. This indicates it is a change in the terminus region, that is changing the force balance within the glacier system. The Jakobshavns is easily 300 km wide in the upper accumulation zone and constricts to 6 km wide in the fjord reach. This constriction does lead to the glacier having such a rapid speed. The ice streaming nature of the glacier extends some 60 km inland from the terminus, but the acceleration does not extend this far. This is still only a small percentage of the distance to the head of the glacier and does not reach the area where thickenning is noted. A 0.67% increase in thickness in a portion of the accumulation area, will not make the glacier flow faster in the accumulation area. If it does not flow faster there it will not flow faster in the ice stream section. The glacier is 50 times thinner in the ice stream section but also moves close to 50 times faster, which is a necessary volume balance. Picture a traffic jam. If more cars come into the back of the traffic jam, and cars in front are forced ahead faster, how quickly does this affect flow at the front of the jam? An increase in traffic flow at the front of the jam does communicate somewhat into the jam? This is not ice, but does provide some reference.

    Second #34: We do not have data indicating that Greenland glaciers were moving faster during the period prior to 1950. Thus, the current change is not necessarily comparable.
    As to non-tropical glaciers I have seen four glaciers disappear in the last decade. Despite having already retreated, thus requiring even warmer conditions than before to continue the retreat, the rate and ubiquitous nature of current retreat in the Alps, North Cascades, Himalaya, Andes and other areas is unprecedented since 1900. Wikipedia Glacier Retreat covers this in detail.

    Comment by Mauri Pelto — 3 Mar 2006 @ 8:48 PM

  37. I have been tracking the global warming debate back and forth for some time now, and truthfully for someone who approaches the issue from objective point of view it is exhausting. The point, counterpoint, counter counterpoint, and so on is endless. I have no reason to believe your account over others, or their account over yours. Everything has ring of legitimacy and everything is cloaked in the interpretation of dubious statistics. We need a better model for this, we need a better model for that, we need more data here … I’m sorry, but as an outsider reading both sides I can only conclude there is a lot of passion but very little substance. No offense, but anything that has this many interconnecting parts, unknowns, overly simplistic models, and noisy data is getting nowhere slowly. We will just have to wait. Only then can we look back in retrospect to see who was right, and even then thanks to the miracle of cognitive dissonance, magically somehow those in the wrong will find a way to spin it so they weren’t really wrong after all. I give up.

    Comment by Ian — 3 Mar 2006 @ 10:04 PM

  38. Re #37: I suppose you can come to that conclusion if you grant equal weight to the vast majority of climate scientists on the one hand versus a tiny handful of outliers (most of them funded by the fossil fuel industry) on the other. Simply waiting might be a little dangerous. Have you read Jared Diamond’s “Collapse”?

    Comment by Steve Bloom — 3 Mar 2006 @ 11:35 PM

  39. Re #38: I’ve seen this ad hominem attack a few times. Could you list the scientists (outliers you call them) and which fossil fuel industry is funding them. Personnally, I feel the earth is warming. A proportion of this warming is natural variation and the rest is AGW. What that proportion is remains beyond my grasp. I think scientists on both sides of the debate are doing the best they can with limited knowledge to uncover the truth.

    Comment by Tony Knudson — 4 Mar 2006 @ 12:23 AM

  40. Re #39: It’s not an ad hom given the extensive evidence. I suggest starting with the narrative discussion here. Other useful pages are (essentially a links page) and . Ross Gelbspan’s book “The Heat Is On” is very good on this subject as well, but isn’t on the web.

    Maybe somewhat telling relative to the current news and discussion on glaciers is that the skeptic/denialist side appears to lack even one glaciologist. The same seems to be true of most fields related to climatology.

    Comment by Steve Bloom — 4 Mar 2006 @ 1:09 AM

  41. There simply is no scientific debate left on these points:
    – the earth is warming rapidly
    – the warming is primarily driven by human actions
    – the warming will very likely continue and accelerate unless GHG emissions are reduced or offset in some way.

    The political debate does not care about scientific validity. The scientific debate is now about how much and how fast will temperature rise, how quickly will sea level respond and what will be the exact impacts on regional climates and the biosphere.

    Comment by Coby — 4 Mar 2006 @ 1:31 AM

  42. Ian,

    If it is too hard for you to tell for yourself, what is wrong with trusting the experts in the field? All of the major scientific institutions dealing with Climate, Ocean, Atmosphere and Earth Sciences agree with the conclusions of the IPCC. Absent extraordinary evidence showing why they are all wrong, you should not worry about believing them.

    Comment by Coby — 4 Mar 2006 @ 1:34 AM

  43. Why not just trust the experts? I don’t just trust the IPCC sanctioned experts, because I read the sceptics sites and they bring up really good points. I am not a climate scientist, but I do have a graduate level mathematics background and after reading Steve McIntyre paper I can’t help but agree with him. He makes sense. On the other hand glaciers seem to be shrinking, but in some places they are actually growing and ….. ugh. You can’t just write off the sceptics as easily as you would like to, at least I can’t. Crackpots have crackpot arguments and are usually pretty obvious, many of the sceptics have good arguments. Published/peer-reviewed arguments! There is really no distinguishing them if you truly approach the subject from a objective perspective.

    [Response: If you’re at the level of “On the other hand glaciers seem to be shrinking, but in some places they are actually growing and…” and then giving up, you’re not really trying very hard. You’ve just allowed yourself to get confused by the skeptics shouting at you. Try; or perhaps You’ve also allowed yourself to get confused about the state of the literature; there are no skeptic answers to any of the attribution studies – William]

    [Response: Not to mention this nice map: – William]

    [Response: Wahl and Ammann (in press)]

    Comment by Ian — 4 Mar 2006 @ 2:06 AM

  44. #40 Even if everything you said is true, you are missing two very important parts of the debate:
    – How much warming will occur and is it significant (has similar warming occurred naturally in the past and therefore the earth has show the ability to ‘weather’ it just fine).
    – Can we do anything to stop it.

    Although I have tried to be objective the one conclusion that I have come to is that in my opinion there is nothing that we can realistically to do stop it — which makes a lot of the arguing pretty much moot except from an academic perspective. But also that is just my opinion I have formed. If someone can point me to a paper that shows how Kyoto or some such measure would actually make a difference … well I havn’t seem any such paper. Seems like people going on wishful thinking.

    Comment by Ian — 4 Mar 2006 @ 2:23 AM

  45. Tony — here’s one such list, for one big company (shareholders find this sort of thing interesting, and it’s supposed to be disclosed, so it gets collected):

    Documenting Exxon-Mobil’s funding of climate change skeptics. …

    Comment by Hank Roberts — 4 Mar 2006 @ 3:29 AM

  46. This is fascinating new research and understanding of the dynamics of glacier and ice field melting and acceleration coming out of Greenland and Antarctic. Though, it leaves a novice bewildered without the help of an excellent paper by Fountain and Walder: “Water Flow Through Temperate Glaciers”, Reviews of Geophysics, 36, 3/Aug 1998 at —

    It includes a glossary and photos which aid an understanding of the chemistry and physics at work here.

    Much discussion ahead on the recent papers and contributors will benefit from the Fountain/Walder paper.

    And, a housekeeping comment:

    This page is too valuable to be hijacked by commenters who complain about the perks and grand lifestyle of IPCC Working Group members and AGW researchers. And I have a special peeve about wild idea advocates and quick fixers who believe (among other wierd ideas) seeding the melting tundra to fix CO2 back into the vegetation.

    How about creating a BOZO BIN for those contributions that so obviously intend to distract us and worse – make light of the serious topics Real Climate offers for discussion.

    Since we do not ever want to sensor scientists or their opinions, the BOZOS will have their own page to rant and diddle around. The rest of us can keep the conversation flowing closer to truth and understanding.

    I trust the Real Climate managers can make honest judgments and separate the wheat from the gaffs. Please consider this. It will help all of us – even the BOZOS.

    John McCormick

    Comment by John L. McCormick — 4 Mar 2006 @ 10:05 AM

  47. It seems to me that the skeptics have not moved an inch from their position in nearly 20 years. No amount of evidence will ever convince them. They wrap their views in apparently scientific language, in reality however, they are far from being scientific, they are absolutely dogmatic.

    I found this news item:
    This article will help the genuinely open-minded realise the seriousness of the situation and that the majority of climate scientists are very much closer to the truth than any of the skeptics.

    It really sickens me to hear the lament of the skeptics that they are being treated the same as Galileo. The skeptics are the dogmatic ones. Galileo based his views on objective reality, as do the climate scientists. Galileo was hounded by the dogmatic authorities and forced to recant even seeing the moons of Jupiter!

    I often read this site and as I am not a climate scientist, I very rarely make comments, this one was prompted on reading some of the comments in this thread.

    Comment by Lawrence McLean — 4 Mar 2006 @ 11:25 AM

  48. Past the oil era, there will still be a demand for carbon fuels because of portability and energy content. The energy competitors will derive from photoshynthesis, coal, and residual oil. (And manufactured hydrogen)

    So, the glacial cycle puts us in the opposite dillema for the next few millenia, competition for atmosphere carbon. We will be in a race against natural photosynthesis, rather than a race against natural oxidation. But we will also be in a race between regions for atmospheric carbon.

    Hence, an intriguing economic model, the Northern regions hold vast amounts of untapped tundra and forest carbon. As climate engineers, they will want to release that carbon in stages over the millenia as southern regions remove it.

    Comment by Matt — 4 Mar 2006 @ 2:18 PM

  49. As I posted elsewhere, the most important theory that should be applied to the global climate changes we are seeing is Chaos theory and though a few are looking at it from that perspective, most are still applying old models in trying to predict what effects we’re going to see as our planet warms rapidly. Trying to apply any theory or model, such as predicting exactly what will happen in the melting of Greenland, is almost futile as it is part of the beginning stages of a Chaotic event. There are general Chaos Theory principles here that all scientists should begin to adopt related to climate change:

    1. Old models and theories may be valuable but incomplete because there are too many variables and therefore, the system should be considered from a Chaotic perspective…the steady state of the global climate is being disrupted in a unpredicatable way. The more rapid melting of both the Artic and Anarctic regions than predicted by “theory” is exactly what one would expect from a system at the beginning stages of heading into a Chaotic state. The sytems are already outside the bounds of theory and will get further away (as predicted by Chaos Theory).

    2. The best theories for what may be ahead are be those that are based on Chaotic transitions. Unpredictable disruptions, multi-varible events that are far to complex to be modelled, etc.

    3. It may be more of a service to governments and policy makers to let them know that much of what is ahead in global climate change is unpredictable, but better policies would be to plan for disruptions and general catastrophic repsonse coordination. Hurricane Katrina is likely the first of many such examples of the chaotic and catastrophic events that are ahead. Smart policy makers simply should be planning for lots of disruptions as the earth’s climate goes into a chaotic and unpredictable period.

    4. In Chaos theory of course “tipping points” occur, when sudden changes occur rapidly. This was not even considered as possibility in mainstream climate modelling just 10 years ago. Now of course we know that tipping points are very important in the earth’s climate and nothing could be more important for us to understand than finding out just when such points are reached. We may not be able to tell policy makers what exactly will happen after a tipping point is reached, but we can tell them it is unlikely to be pleasant for humans and they ought to prepare for major climate and weather related disruptions.

    [Response:I think your ‘Chaos model’ is a bit too simpistic. True, the ‘chaos theory’ was illustrated by the very simple idealistic numerical Lorenz model on a computer, but we are pretty sure nature is far more complex. The argument that we cannot predict because a system is chaotic is wrong and based on misunderstanding or mix-up of concepts. While it is true that we cannot predict the exact state (eg weather), we may however be able to predict how the pattern of behaviour (climate) may change under altered contitions (forcings). For instance, eventhough we cannot predict the exact weather on Greenland in July (summer), we can be fairly confident it’s going to be warmer than now (late winter). Furthermore, despite the presence of chaos, we can predict milder conditions over Scandinavia for the next winter than say along the west coast of Greenland (same latitude). The reason is that the strange attractor (describing the chaotic behaviour) may shift systematically in the presence of ‘external’ factors. It’s a bit ironical to see that the ‘chaos theory’ is used as an argument against the GCMs, as it was similar type models – albeit numerical weather models – that played a cental role in its discovery, and Lorenz was a meteorologist (the Lorenz model was a simplified ‘atmospheric model’). There is a valid point related to what time scales the system acts chaotically, is it just weather or are there chaotic fluctuations on much longer time scales? Even if the latter is true, external forcings may have systematic effects on our climate. Take the thought example, and say superman towed the Earth away from the sun – it would get colder… And finally, the climate models do describe the chaotic bevavious very realistically. -rasmus]

    Comment by Randall Simpson — 4 Mar 2006 @ 2:20 PM

  50. Re 44, Ian:

    Please read

    These tips from the Union of Concerned Scientists can result in
    significant cuts in greenhouse gas emissions – if widely
    implemented, much bigger cuts than the first round of Kyoto can
    hope for. Most of these tips also reduce cost of living. The money
    you are no longer using to keep yourself alive can saved,
    invested, donated, or put back into the economy. (Aren’t we always
    told consumer spending drives the economy?) There is much that we
    can do ourselves.

    The IPCC’s Climate Change 2001: Impacts, Adaptation and
    Vulnerability, at, and Climate Change 2001:
    Mitigation, are well worth reading, and give an excellent picture
    of how big a difference GHG cuts can still make. The summary for
    policymakers (SPM) for each report is probably what you should
    read first. However, note the IPCC’s Mitigation report is directed
    at governments, which are so far proving much harder to turn than
    aircraft carriers. We can each cut down our own GHG emissions much
    easier than we can bring government regulations into effect.

    But most importantly, no matter how severe climate disruption
    becomes, more greenhouse gasses will always make it worse. (Until
    we run out of GHG sources …) The cost of adaptation is most
    likely nonlinear with respect warming. Probably, 4 degrees of
    warming is more than twice as bad as 2 degrees of warming.

    There is no point at which it might be reasonable to throw up our
    hands and say ‘it’s too far gone, so we should do nothing’,
    because more greenhouse gasses will always make it worse.

    Comment by llewelly — 4 Mar 2006 @ 2:27 PM

  51. John, until killfiles* are implemented for web comments, without burdening the moderators grievously, it helps if we all ignore trolling no matter how tempting the bait. Do not bite. See the history, Usenet was just getting fairly good at this, then the web came along. So it goes.

    Comment by Hank Roberts — 4 Mar 2006 @ 2:28 PM

  52. These warmer winters, are they down to human induced climate change or natural climate variation. A series of warm winters is often the case is it not ?

    Can we show it is down to human induced climate change ?

    Comment by pete best — 4 Mar 2006 @ 2:42 PM

  53. I don’t just trust the IPCC sanctioned experts, because I read the sceptics sites and they bring up really good points

    Firstly, it is not just IPCC santioned experts, the list of reputable scientific organizations that have done the hard work of verification and found the arguments sound is very long, as presented in the link I provided:

    Secondly, the sceptic sites do not bring up really good points. They only sound plausible to people, like most people, who do not have the time or the desire or the ability to verify them. When you do start to verify them you will find they do not hold up. You will also discover quite a few out right falsehoods and this may make you feel like you have been duped and taken for a ride.

    You are also seriously misled to believe that the sceptics are publishing in the reputable scientific journals.

    Don’t give up, keep learning and you will come to the only supportable conclusion.

    “How much warming will occur?” is a legitimate area of debate, but the doubt is between “alot” and “a hell of a lot”, not between “a bit” and “nothing worth worrying about”.

    “Can we do anything about it?” is a socio-political issue, not a scientific one, though there is surely alot of good science needed to make sure we know the best choices.

    Comment by Coby — 4 Mar 2006 @ 3:35 PM

  54. Ian —

    I found the following two books of considerable value in understanding modern climatology (and being able to follow RealClimate posts):

    W.F. Ruddiman
    “Earth’s Climate: Past and Future”

    F. Oldfield
    “Environmental Change: key issues and alternative approaches”

    Comment by David B. Benson — 4 Mar 2006 @ 3:43 PM

  55. Re #49
    I feel that no serious scientist could disagree with your post.
    You are right. “….the most important theory that should be applied to the global climate changes we are seeing is Chaos theory and though a few are looking at it from that perspective, most are still applying old models in trying to predict what effects we’re going to see as our planet warms rapidly…..”
    Most of us are worried due to our ignorance. Models are extraordinarily useful, but are empirical tools no matter how complex they are.
    The more we know greater is our concern about our ignorance.

    Comment by grundt — 4 Mar 2006 @ 4:29 PM

  56. Thank you to those who have posted further references. I guess I won’t give up trying to understand the situation quite yet and will do some further reading, but I will also read Patrick Michaels books for a balancing perspective. Keeping objective is hard, but I want to seriously attempt to do so. I have a further question (one of the minutiae from the infinite minutiae that seeme to arise in this area). Looking at the rising CO2 it most definitely seems to have a strong linear trend. However, I would expect the trend to be exponential (exponential GDP, exponential population growth …). Does anyone know of a mechanism to explain why CO2 growth has been linear instead of exponential? Maybe it is as simple as increased absorption by the oceans (but don’t warmed oceans release CO2?), or perhaps it is in additional biomass growth (fertilization effect of CO2). Again … ugh. It seems to me ironic that only a decade ago or so I remember articles talking about “the end of science” as if we were close to knowing everything, but obviously those authors had not looked very closely into climate science ;-)

    [Response: What time period are you thinking of? See – William ]

    Comment by Ian — 4 Mar 2006 @ 5:01 PM

  57. Just a note to moderators. It is admirable to try to keep the conversation high-level and to reduce the amount of spam, unnecessary flaming, etc. Unfortunately there seems to be quite a large delay between posting and that posting showing up on the site. This seems to really drag out threaded conversations. Perhaps this is just an unavoidable trade-off.

    P.S. To those that posted book references, I am heading to the store right now to take a look ;-) but also as I mentioned I will browse through Patrick Michaels and the “other side” books as well.


    Comment by Ian — 4 Mar 2006 @ 5:05 PM

  58. #49 While the chaos approach is interesting I don’t know if it really adds very much. The thing about chaos is that you do not know the effect of a perturbation, and “stuff” will happen even without any obvious perturbations. In fact, skeptics could easily latched on to chaos theory as an example of why not to worry about global warming (if random inputs, or indeed no inputs results in random outcomes, then outcomes are outside of our control — so why worry about it).

    Comment by Ian — 4 Mar 2006 @ 5:22 PM

  59. Ian, get a copy of the Patrick Michaels book “Meltdown”, and read chapter two very carefully. A lot of common skeptic myths are dismissed in this brief but reasonable overview of climate science. But note while he is critical of the results of climate models, he confidently predicts the next 100 years based on simple extrapolation, which is a rather simple-minded model.

    Comment by Blair Dowden — 4 Mar 2006 @ 6:06 PM

  60. #56 William — Specifically I am thinking of this graph — and those like it i.e. the actually measured increase of CO2 in the atmosphere.

    Comment by Ian — 4 Mar 2006 @ 6:27 PM

  61. Sorry my last post was not very clear. Yes of course there is absorption by oceans and other natural processes to absorb CO2. I guess if the absorption functions were logarithmic then that would transform an exponential growth of CO2 production into a linear growth of CO2 concentration in the atmosphere. Anyways it was just a curiosity. Totally getting off track. Time to go read some books.

    Comment by Ian — 4 Mar 2006 @ 6:35 PM

  62. Ian,

    If you’re going to read Patrick Michaels, I do hope you keep in mind that he’s been caught blatantly lying about Jim Hansen’s 1989 predictions. He was caught doing it in testimony to Congress. Despite his lie being pointed out, he continues to repeat it.

    Personally, I don’t pay much attention to proven liars …

    Comment by Don Baccus — 4 Mar 2006 @ 7:08 PM

  63. Re #14, #21, #25,… At the risk of annoying Ray P. again, on the “X started in 1850” argument I find myself closer to Ferdinand and John Finn than to him or Dano. If we observe an X event occurring around 1850 and then again around 1910 and 1978 it is reasonable to ask ourselves “did the same cause Y necessarily provoke X in all 3 cases?” But much more pertinent in the context of this debate is to ask ourselves “how can we be so sure that it is Z what caused X in 1978 if we still don’t know what exactly caused X in the 2 previous occasions?”

    I think that the burden of proof clearly lies on the side advocating that Z provoked X in the 3rd case but (obviously) not in the 1st or the 2nd one. Assuming that the same kind of force Y must have been behind all three X events seems in principle the logical thing to do and one need not justify it further until all 3 events and their causes are well understood.

    Besides, the corollary Ray P. imposes on Ferdinand’s argument is unreasonable. Very long before the whole Greenland ice-sheet melted away (!) we would all conclude that it was not quite X what we were observing this time but something of a different nature and causation.

    Comment by Mikel Marinelarena — 4 Mar 2006 @ 10:20 PM

  64. Re #62: I haven’t read any of Michaels’ books, but do bear in mind that he has also been caught out a fair number of times fabricating claims on his World Clinate Report site, the latest instance being just last month as described in the last paragraph of my comment 7 above. As someone else noted, many skeptics engage in this sort of tactic because most of their readers lack either the necessary journal subscriptions or the time to check the facts themselves.

    Comment by Steve Bloom — 4 Mar 2006 @ 10:35 PM

  65. Re #40 **I suggest starting with the narrative discussions here**
    – Rather a slanted discussion. No further comment.
    Re #41 **the warming is primarily driven by human actions**
    – I do not know of any study which has measured the percentage of the warming due to human activities. All I see is statements.

    Comment by Gerald Machnee — 4 Mar 2006 @ 10:47 PM

  66. Re #63: It’s an interesting dilemma you pose, Mikel. Do we have any means of knowing the exact degree of insolation in 1850? No? So really you’re saying that we can never draw any conclusions with regard to the present glacial retreat even though modern measurements techniques allow us to exclude insolation changes as a major factor. Or are you arguing that there is some other cause entirely for the 1850 retreat that we don’t know about and/or can’t measure? I would suggest that a better approach would be to take our modern knowledge and measurements of all of the possible forcings and engage in a detection and attribution analysis to figure out the cause(s) of the retreat. It’s useful to look at historical glacier records to see if the results of our D+A exercise makes sense given what we do know about the history of the various forcings, but that can never be an exact exercise. I suggest you carefully read comment 36 and the responses to 43, plus look at the linked material.

    Comment by Steve Bloom — 4 Mar 2006 @ 11:04 PM

  67. RE: 49,55,58 and mathematical methods.

    The obvious method, must have already been done.

    Take the glacial function over as many periods as we have acccuracy for. Deconvolve the known solar forcing function, perform a least squared frequency analysis on the rest, and of the frequency response, retain only the moments you know are related to ocean/ice timescales. The rest would be the biomass forcing functions, short term ocean circulation, and geologic changes.

    This approach gives us very important information if we can go back to a particular cycle, remove the solar and ocean/ice driver, then look at the result as possibly changes in biomass feedback from cycle to cycle.

    But, this is what everyone is doing, I presume.

    Comment by Matt — 4 Mar 2006 @ 11:21 PM

  68. Re #64: Gerald, just as it’s hard to figure out the right gift for the person who already has everything they need, it’s hard to know what to say to someone who questions the entirety of climate science while believing that it’s all based on some sort of International Climatological Conspiracy involving the IPCC, the national academies of science, most climate scientists and all the major environmental organizations. All I can think of is to suggest that you read the History of Global Warming and the TAR, both of which are linked from this site. To get the answer to your attribution question I’m afraid you’ll have to read the hard bit of the TAR, which unfortunately will take a bit more time and concentration than “Climate of Fear” did. Sorry to be so brief, but the weekend is short and my tsunami generator is in desperate need of a wash and wax. :)

    Comment by Steve Bloom — 4 Mar 2006 @ 11:22 PM

  69. To #55:

    That certainly could be one argument made to do nothing…but in fact, Chaos Theory is quite scientific and of course quite mathematical too. Going in line with even the uncertainty of quantum events themselves. But what scientists can begin to say to policy makers and others is this: We can’t tell you exactly what will happen, but we can tell you that it will not be pleasant. In this sense Lovelock is exactly right…he senses the tipping point is already passed and that something quite nasty is ahead. this is Chaos Theory applied to Gaia and global systems. Just like when you stick your hand under a smooth running stream of water, and the spray is Chaotic by nature, you know that you’re going to get splashed, but no theory in the world can tell you exactly where any individual drop will fall. This is the message that scientists, in all good conscience must begin to get across to policy makers. We don’t know exactly where the next mega-hurricanes will occur, but we do know they will occur because of global warming and we do know that people in their path will get hurt.

    Chaos Theory is quite precise is telling us how systems reach tipping points and then go chaotic. This is the most important message and one that Lovelock is once more ahead of the pack on. For him, he’s convinced some major tipping point is already past and we’re headed for extremely chaotic and species threatening events. His message seems radical now…just like Gaia did 20 years ago, but I wonder how it will sound 20 years from now after we’ve experienced whatever Chaotic climate events are just ahead.

    One final note in my long winded reply: One of the greatest unknowns right now is the methane clathrates. With Siberia and other northern hemisphere permafrost melting…this positive feedback loop with methane being so much more potent a greenhouse gas and being released now from these regions is something that only increases the Chaotic nature of what lies ahead.

    Comment by Randall Simpson — 5 Mar 2006 @ 1:02 AM

  70. I read and reread the post on Lovelock, and the thing that strikes me his his choice to stabilize at the glacial maximum. In the background, some mute voices make a similiar plea, that if we are to be stuck, then is the glacial minimum the right spot? A quick glance would suggest one choice for best spot is the glacial midpoint, for that spot is mid-range in the ice/water interface, the most linear region, the spot where we can have the most control.

    I am assuming the majority will prevail, and we will be stuck at these temps for some time, with some blips along the way. It often bothers me that the global warming alarmists seemed so intent on defending the glacial minimum, for the ice data tells me that is the most unstable.

    But this seems strange, because if it was so unstable, then how are we stuck here? That question is the most haunting, for to have such a stable point, just a degree celsius from a very unstable point, indicates an extreme non-linearity.

    Comment by Matt — 5 Mar 2006 @ 2:38 AM

  71. #68 Stick ourselves at glacial maximum in a chaotic system … Interesting idea, but I doubt we have the necessary understanding or control. Can anyone flap their arms in just the right way to stop the next hurricane yet?

    Comment by Ian — 5 Mar 2006 @ 3:11 AM

  72. re 40 41 64

    In 64, Gerald Machnee wrote … “I do not know of any study which has measured the percentage of the warming due to human activities. All I see is statements.”

    During the last 50 years, polar ice, glaciers, ice sheets and permafrost have been thawing much too rapidly to be from anything other than human activity. In thawing episodes in Earth’s past, given similar starting conditions as 50 years ago, how quickly were polar ice, glaciers, ice sheets and permafrost areas reduced within a 50 year period? I think we all should know the answer to that question… minimally. Thus, the percentage of global warming due to non human activities now is minimal, i.e essentially all global warming since the 1960s is due to human activity, mainly from our greenhouse gas emissions. There is no need to attempt to extract a minimal effect on global warming from non human activity, it’s too small to measure or estimate.

    Comment by Pat Neuman — 5 Mar 2006 @ 8:09 AM

  73. I usually work on the assumption that the phrase “chaos theory” is an HTML tag meaning “insert handwaving here”. Is there really any other intellectual concept that is the basis for as much ill-thought-out bollocks?

    Comment by Alex — 5 Mar 2006 @ 10:06 AM

  74. Re #72 – You illustrate exactly what I have been pointing out – NO DATA or CALCULATION. You then pick an abstract number – 50. You then make a statement “Thus, the percentage of global warming since the 1960s is due to human activity, mainly from greenhouse gas emmissions. There is no need to attempt to extract a minimal effect on global warming from non human activity, it’s too small to measure or estimate.” – with no backing.
    It does not look like you have been following to discussion of the Greenland Ice Cap or you would have seen some discussion of measurements of flow and thickness. Summarizing the points, it indicates that the ice cap has been advancing and retreating over the last 150 years of records. However the records are not perfect so a definite conclusion cannot be made even though some scientists have tried to say that based on the last 10 years or so, the ice cap is retreating and the oceans will rise significantly. Some have made this their whipping boy for rising sea levels. You are treating AGW like a religion.

    Comment by Gerald Machnee — 5 Mar 2006 @ 10:22 AM

  75. re 74 Actually,

    In 72. I wrote … During the last 50 years, polar ice, glaciers, ice sheets and permafrost have been thawing much too rapidly to be from anything other than human activity. … i.e essentially all global warming since the 1960s is due to human activity, mainly from our greenhouse gas emissions. There is no need to attempt to extract a minimal effect on global warming from non human activity, it’s too small to measure or estimate.


    I’ve seen the recent data, calculations, and photography, including video presented at the Minnesota state capitol in 2005, by polar explorer and dog-sledder Will Steger from Ely, MN.

    I’ve studied the Cretaceous and Paleocene/Eocene evidence, and subsequent. There is nothing remotely close to the high thaw rate with similar starting conditions. GHG emissions are now at rates determined to be 30 times larger than the rate of GHG emissions which contributed to the Paleocene Eocene Thermal Maximum, about 55 myrs ago, according to a presentation given last month in St. Louis by Dr. Zanchos. We’ve spent way too much time looking back for things that aren’t there or don’t matter much. It’s beyond the time to focus on the future of the planet. Forward!

    Comment by Pat Neuman — 5 Mar 2006 @ 12:03 PM

  76. Re #75 – Pat, your last paragraph does not entirely make sense. There was no thaw rate in the Cretaceous or Paleocene/Eocene because there was no ice. There have been rapid melting rates in the past, eg. at the end of the Younger Dryas. Present GHG emissions may be higher than during the PETM, but those lasted for thousands of years. If we are smart we will stop long before that, hopefully as soon as possible.

    But there is no credible explanation for the warming of the last 40 years that does not involve anthropogenic greenhouse gases. One study claimed it might be 10% to 30% solar, a) that is disputed, and b) so what?

    A relevent observation from paleoclimate data is that the previous interglacial period (the Eemian) was one or two degrees warmer than the current one, and sea levels were 6 meters higher. The question is how long did it take for this sea level rise to occur?

    Comment by Blair Dowden — 5 Mar 2006 @ 12:32 PM

  77. In 75. Blair wrote … “There was no thaw rate in the Cretaceous or Paleocene/Eocene because there was no ice.”

    Blair, I’ve seen studies and articles that refer to ice during the Paleocene Epoch. I posted this excerpt and link to RC in Oct or Nov of 2005. There are other studies (in Science, which mention sea level changes from rapid ice thaw in the ancient past, some as rapid as over thousands of years, but none as rapid as over hundreds of years.

    Large (“rapid”) climate changes preceded the PETM, 65-55 mya, as shown
    in work by Robert Speijer. “A relative sea-level fall (~30 m)
    immediately preceded the late Paleocene thermal maximum, during which
    sea-level rose again by ~20 m. This rise may have been eustatically
    controlled, possibly through a combination of thermal expansion of the
    oceanic water column and melting of unknown sources of high-altitude or
    polar ice caps in response to global warming.”

    Comment by Pat Neuman — 5 Mar 2006 @ 1:03 PM

  78. Today’s Doonesbury cartoon:

    Comment by Hank Roberts — 5 Mar 2006 @ 1:38 PM

  79. re 77 … “Based on sea-level history, we have proposed that ice sheets existed for geologically short intervals (i.e., lasting ~ 100 ky) in the previously assumed ice-free Late Cretaceous-Eocene Greenhouse world (36).” … These ice sheets existed only during “cold snaps,” leaving Antarctic ice-free during much of the Greenhouse Late Cretaceous-Eocene.” …

    25 Nov 2005 article in Science, The Phanerozoic Record of Global Sea-Level Change (Miller, K.G. et. al.).

    Comment by Pat Neuman — 5 Mar 2006 @ 2:39 PM

  80. Re: #43
    Those wishing an independent evaluation of the science of past temperature reconstruction may wish to follow the progress of the National Academies’ project “Surface Temperature Reconstructions for the Past 1,000-2,000 Years: Synthesis of Current Understanding and Challenges for the Future,” which had its first meeting and heard testimony last week. Reporters were in attendance, so accounts of the meeting may become available to the general public.

    [Response:. The most significant development here is the paper that has just gone to press by Wahl and Ammann]

    Comment by Armand MacMurray — 5 Mar 2006 @ 5:49 PM

  81. re 75. Correction to spelling of name: James Zachos, professor of Earth sciences at the University of California, Santa Cruz

    Ancient Climate Studies Suggest Earth On Fast Track To Global Warming

    by Staff Writers
    Santa Cruz CA (SPX) Feb 16, 2006
    Human activities are releasing greenhouse gases more than 30 times faster than the rate of emissions that triggered a period of extreme global warming in the Earth’s past, according to an expert on ancient climates.
    “The emissions that caused this past episode of global warming probably lasted 10,000 years. By burning fossil fuels, we are likely to emit the same amount over the next three centuries,” said James Zachos, professor of Earth sciences at the University of California, Santa Cruz. …

    Comment by Pat Neuman — 5 Mar 2006 @ 6:09 PM

  82. The climate of the Cretaceous is still not well understood. We are unable to explain why warmth was so evenly distributed between the equator and poles. Now we have evidence of rapid sea level changes (how often these occur is not said) that can be best explained by short (100 ky) glaciations, but no evidence of such events. If true, the interesting question is what kind of cooling event triggered them? I have not seen an explanation of the 30 m sea level fall preceeding the Paleocene Eocene Thermal Maximum (PETM).

    As for the article on the Zachos study, they claim 4.5 trillon tons (4,500 gigatonnes, or Gt) of carbon entered the atmosphere in 10,000 years, ie. at a rate of 0.45 Gt / year. Present emissions are around 7 Gt/yr, which I make to be about 14 times higher, rather than 30. 5,000 Gt is the estimated coal reserves, and it is very pessimistic to assume we will burn it all in 300 years. Surely we will invent better technology before then.

    Comment by Blair Dowden — 5 Mar 2006 @ 9:51 PM

  83. WRT “Surface Temperature Reconstructions for the Past 1,000-2,000 Years: Synthesis of Current Understanding and Challenges for the Future,” the schedule of the first meeting is at

    It looks like something I am sorry I missed, but still I think “taking testimony” is the wrong description. They use the term “invited speaker” which is more in keeping with NAS processes I am familiar with.

    Comment by Eli Rabett — 6 Mar 2006 @ 12:28 AM

  84. The comments on the Cretaceous period and that other thermal maximum sent me off looking things up only to discover man is planning to mine methane hydrates and convert coal to portable carbon fuels.

    There will be a continual need for 2-3 Gigaton/year of portable fuel emissions for another 300 years. It doesn’t matter where you get it, the only solution is to have photosynthetic carbon be more competative than the alternatives, either by collective wisdom or dynamic markets. We need economic incentives to extract atmospheric carbon, even if we need 75 year planning cycles.

    Back to climate. How is the climate going to be for large scale carbon sequestering during the warm period?

    Comment by Matt — 6 Mar 2006 @ 3:25 AM

  85. Matt – I would say it is a bit unwise to try to project human fuel usage 300 years into the future. Photosynthetic carbon is not really a long term alterative in any case; farming is by definition very destructive of the environment.

    Methane hydrates are a very unlikely fuel source indeed; they are far too distributed in nature.

    Comment by Andrew Dodds — 6 Mar 2006 @ 4:27 AM

  86. Re: Response to No. 80. Where is the Wahl & Ammann paper to be published?

    Comment by PHEaston — 6 Mar 2006 @ 8:46 AM

  87. Re: Steve Bloom’s Comment #64 and #7


    I don’t see where you are going with these comments. According to my copy of Rignot and Kanagaratnam (R+K) the date of submission of this article was October 14, 2005. According to my copy of Johannessen et al. (J et al.) it was published on-line on October 20, 2005. Although your timeline (re:#7) is wrong, the point I guess you are trying to make is that R+K did not reference J. et al. because J et al. was published a week AFTER R+K was submitted. However, this seems to neglect that period between October 20, 2005 and January 17, 2006 (the date R+K was accepted) during which time any of the reviewers and, in fact, R+K themselves could have modified their text to include at the very least a reference to J. et al. Reviewers suggesting that references should be added happens all the time. In fact, in a new paper that we have under review examining the relationship (or lack thereof) between SSTs and hurricane strength (which we hope will appear in the peer-reviewed mainstream scientific literature belive it or not), we added references (to our original submission) at the insistence of reviewers and, in fact, added an additional reference ourselves to a brand new paper that was published AFTER our original submission. There was plenty of opportunity for R+K to have done the same in regards to J. et al.

    Further, as the RC article mentions, in addition to the interior Greenland mass gains reported by J. et al., the study by Zwally also reported mass gains. Therefore, it would seem appropriate to ask, as Pat Michaels did, why then did R+K only decide to incorporate the interior mass loss modelled (rather than observed) by Hanna et al.

    Heck, even RC doesn’t suggest that using Hanna et al was the correct thing to do. Instead, they point out simply that the losses reported by R+K were larger than to gains reported by J. et al. and Zwally et al. And this is what R+K probably should have done–recognize the results of J. et al. and Zwally et al. and then put them into context–not simply ignore them and use Hanna et al. instead. This gives the impression that they were attempting to make their results more extreme and thus noteworthy.

    As always, we invite everyone to fact check our stories and we make every attempt to provide the references to do so.

    And further (re: #64) it is not a valid criticism that we make reference to articles in journals that no one else has access to. A trip to the nearest University library should remedy that situation. That’s what we do!


    [Response: You’re missing the point of the criticism. The criticism isn’t that professionals with time to delve into the literature fail to check your facts. The remark only says that World Climate Report can count on getting away with misquoting or distorting the scientific literature because most of your readers don’t bother to do so, still less the newspaper reporters who used to quote WCR for the sake of “balance.” If more people checked your spin on the issues (and that is one of our jobs here at RealClimate) WCR would probably lose what little credibility it has left. –raypierre]

    Comment by Chip Knappenberger — 6 Mar 2006 @ 12:14 PM

  88. Dodds –

    I am going to have to challenge you a little on this fuel use projection.

    The steam engine is 300 years old. For 100 years the four cilinder carbon combustion has been the transportation of choice. The peak oil projections from: have us using oil 50 years from now at 1960 levels, and extending their graph beyond has us using at 1950 levels in 75 years. I have not seen serious projections of a commercial fusion reactor for 50 years. Carbon and hydrogen are the only real energy carriers in contention. The population will still be in the billions at 2300. Automotive manufacturing has a depreciation life of nearly 75 years. Rail transportation still occupies a second place to the automobile.

    If we are not using mainly carbon as a portable fuel in 300 years, then give me the alternative.

    Comment by Matt — 6 Mar 2006 @ 2:03 PM

  89. I find it fascinating that, reading raypierre’s reply to checking source material (current 87), the comment immediately above asks where a paper is to be published. The journal name is both in the HTML page properties (the joys of tabbed browsing) and in the abstract immediately below the affiliations.

    I guess that is a good example to make Steve Bloom’s point (and my often-stated point, just not here). The skeptics get away with some of their standard tactics because no one “audits” their work.



    Comment by Dano — 6 Mar 2006 @ 2:30 PM

  90. Re #87: Thanks, Raypierre. Chip, there might have been something to what you say except for the fact that the editors of Science, recognizing the need for all of these results to be synthesized, commissioned Dowdeswell to do just that (and in the same issue as R+K). You then proceeded to attack the editors and R+K for their failure to address the material Dowdeswell covered, and never told your readers that Dowdeswell even existed. But of course if you’d done so, the whole premise of your article would have evaporated.

    Comment by Steve Bloom — 6 Mar 2006 @ 3:18 PM

  91. Gerald, Re #74 —

    I’ll do a rough-and-ready calculation of the proportion of GW which is AGW, and obtain vastly more than 100%! The argument depends upon probability and some work on Ruddiman, specifically
    the figure on page 83 of F. Oldfield’s book cited previously in comment #52. First the probabilities, given via a standard marble-in-box argument.

    There is a line of eight boxes, the first seven of wood and the last carved from jade. Each box contains a marble, either black or white. Before opening the first box, you need to have some a priori probability that the marble is black. Suppose you choose 50%. So after opening the first seven boxes and discovering all the marbles are black, you are now in a position to assign a probability to the hypothesis that all marbles are black, 99% and a little more. But upon opening the last box, the one of jade, the marble is white. So either you were terribly unlucky or else you require a more refined hypothesis in which the nature of the box, wood or jade, is taken into account. At this point, the hypothesis that all wooden boxes have black marbles is well supported, 99%. About jade boxes there is only the one observation on a white marble. The hypothesis that jade boxes are different from wooden boxes, regarding the color of the marble inside, is also highly confirmed.

    The climate hypothesis, corresponding to all boxes, is that after every time in the Vostok ice core record that methane concentration rose above 550ppb, it then declined subsequently
    following orbital forcing. Looking at the figure cited just above, the first seven times support the hypothesis. Using the wooden box analogy, this hypothesis is now highly confirmed. However, the eighth is the Holocene and like the jade box we discover something very different: not only did methane concentration fail to decline, it rose dramatically, in complete disaccord with the previous 400,000 years of methane concentration records. Clearly the Holocene is a jade box.

    Thus my claim of more than 100% of GW is AGW. Methane etc should be declining, not rising.

    Ruddiman’s book “Plows, Plagues and Petroleum” makes the case in a different manner, and for a non-technical audience.

    Comment by David B. Benson — 6 Mar 2006 @ 3:51 PM

  92. Dr. Pierrehumbert (re: #87 response),

    The funny thing is, I always thought that we (World Climate Report et al.) existed to counter the alarmist spin on this issue and do the work for the man-on-the-street who doesn’t have the time and resources to fact check everything he reads or hears in the media. And now RC exists to counter us.

    My this is a cozy little self-perpetuating existence that we have created for ourselves isn’t it!


    Comment by Chip Knappenberger — 6 Mar 2006 @ 3:57 PM

  93. Please respond to the criticism of your description of the Science Magazine contents; if you made a mistake, correcting it is appropriate.

    Comment by Hank Roberts — 6 Mar 2006 @ 4:46 PM

  94. Chip (92), you can go on sci.env to see a rich history of folk pointing out stuff that ‘counters’ ‘you et al.’, so I don’t see that particular niche being filled in quite the way you say.

    Unless you mean that the folk that write the source material are addressing ‘you et al.’ now, instead of people who read the articles and regurgitate the scientific literature…



    Comment by Dano — 6 Mar 2006 @ 4:49 PM

  95. #47. 20 years ago I was a borderline Earth Firstoid, hard core Gaia worshipping worst case scenario promoter. I subscribed to the world views espoused by Amory Lovins, Malthus and James (“Greenhouse: It WILL Happen in 1997.”). Now I am not so sure. I don’t work for big oil. I *do* work for big “we are going to get rich if people take Kyoto seriously.” Sorry that I don’t fit into your pigeonhole. I am a skeptic even in the face of my own financial conflict of interest (which would make me, in terms of raw interest, a natural “warmer”). I am therefore a pure skeptic, with absolutely no conflict of interest pushing me in that direction. Only my own sense of ethics pushes me in that direction.

    Comment by Steve Sadlov — 6 Mar 2006 @ 5:10 PM

  96. #48. At some point, it will have to come to resemble the precious metals economy albeit with a much more intensive recyling component “fueled” by photosynthesis. That is, unless we colonize space and find a new home that is as good as or better than Earth.

    Comment by Steve Sadlov — 6 Mar 2006 @ 5:13 PM

  97. Re:#83
    Eli, “taking testimony” was purely my own phrasing, intended to describe the speakers giving 45-minute presentations, answering questions from the panel, and participating in the open discussion. I’m sure there’s a better phrase for that process… :)
    Also, there are some initial reports of the events there at climateaudit (for those who don’t know, the site is what many here would call a “skeptic” site).

    Comment by Armand MacMurray — 6 Mar 2006 @ 5:27 PM

  98. I am yet another concerned layman who has been following the climate change debate for 20 years or so,
    and I am left with a feeling that a very major aspect is been neglected by those most able to address it, namely professional climate scientists. That is the way that one aspect of the changes brought about by elevated co2 affects another and so on that often changes the base assumptions of The rate of melting of say the Greenland ice cap is based on an assumption about likley global temperature rise which in turn is based on expected levels of atmospheric co2.
    Projected rates of rise of co2 (for given anthropogenic emissions scenarios) assume (?) that current natural carbon sinks remain basically unchanged but melt water from say Greenland may reduce the thermohaline circulation which would reduce the rate of absorbtion of co2 by the oceans (various mechanisums such as reduced displacment of co2 rich surface water by co2 poor deep water, reduced activity of photosynthetic plankton because of reduced nutrient levels, loss of shell forming plankton due to acidification, all of which resulting in higher than projected atmospheric co2 for a given anthropogenic emmissions scenario. This would then lead to higher than projected air temperatures (also as a result of higher sea surface temperatures due to reduced mixing) with consiquent increase in the rate of melting of Greenland ice and so on. Do you see the point.
    I know that there are enormouse uncertainties in maney of these effects but I think someone ought to do a best guess calculation because I think that in these ,as yet, unquantifiable feedback loops the potential for more rapid and extreme climate change than is currently been predicted is present.

    A quick personal response to this comment would be much appreciated if it dosen’t merit posting on the blog

    [Response: This is indeed a plausible postive feedback on CO2 concentrations, as are melting permafrost releasing carbon, changes in soil respiration as a function of temperature etc. When they are quantified (though they are still uncertain) they add up to about a 10% increased effect (if memory serves me – you might want to look up some relevant literature – Friedlingstein et al, and Cox et al have published on this). However, the postulated increases in CO2 from fossil fuel sources completely dominate what is likely to happen. -gavin]

    Comment by Peter wright — 6 Mar 2006 @ 6:01 PM

  99. Re #91 – you have also illustrated my point. So if you come up with more than 100 percent you are exagerating and also making errors in math. I would sometimes get 100 percent in math and science(before multiple choice), but, damn, I could never get more than 100. I have heard of hockey players putting out at 110 percent, but I did not play hockey.
    To measure the percent of AGW contribution, you have to get right into it, marbles may illustrate a point, but they have not measured it. So, it remains – we may have increased the temperatures in the last several decades – but what caused it?

    Comment by Gerald Machnee — 6 Mar 2006 @ 6:09 PM

  100. 95:

    Speaking of recycling and comics in another thread, I’m reminded of a comic that highlighted a similar tactic a couplea years ago, that approached the anecdote assuming about the same level of credulity.



    Comment by Dano — 6 Mar 2006 @ 6:16 PM

  101. Re #99 —

    Gerald, I am sure I could have phrased it better. Comment #91 points out that all the warming is AGW but also there is the gap between the predicted cooling during the Holocene and no cooling or warming at all. That gap is what I meant by more than 100%.

    So I did get right into it. The marbles illustrate the point that we expect the future to be like the past. It is not. The globe should be cooling slightly. It is not. The highly confirmed cause is the increase in greenhouse gases. And we know what/who put those there, don’t we?

    I don’t know how to reply to your last (and new) point: “we may have increased the temperatures in the last several decades — but what caused it?” Are you aware of the effects of greenhouse gases? If not, that is what caused it. If so, I do not understand your question.

    Anyway, I hope I have clarified that I did do the calculation. It was so easy that climate scientists, who have other things to occupy themselves, couldn’t be bothered. In this comment I hope I have sufficiently explained why I said “more than 100%”.

    Comment by David B. Benson — 6 Mar 2006 @ 6:28 PM

  102. Regarding the comment for 98 on the Friedlingstein et al and Cox et al studies regard positive feed back of land process:

    How positive is the feedback between climate change and the carbon cycle? , a 2003 article.

    If I read this correctly, the authors conclude about 180 ppm due to land feedback when the total co2 reaches 980. So a 600 ppm rise (from today) yields a 180 ppm feedback, starting from the current position, or 30%.

    Comment by Matt — 6 Mar 2006 @ 7:51 PM

  103. Hi David (#s 91 & 101). I understood where you were going with that. But I have a different question. Why were you 99% sure after the first 7 boxes?

    This relates to a problem I have been having using the binomial expectation to calculate standard deviations for low proportions. It’s a frequentist thing to do, whereas a Bayesian approach is probably better (but I don’t know how to do it). In any case, to adjust for the limited sample size, and using your prior of 50%, I would have estimated the frequency of black marbles to be 7.5/8 = 94% (I added one marble with a 50% chance of it being black). That’s the proportion I would have used in the binomial formula for the purposes of determining my ‘certainty’.

    So I guess I’m asking for an explanation of 99% and for some help in my own problem.

    Comment by Steve Latham — 6 Mar 2006 @ 9:13 PM

  104. Re #103 —

    For my argument in #91, 94% would work almost as well. I’m not sure that a Bayesian would approve of the fast method I used. I’ll work out the correct details tonight and post it tomorrow afternoon, PST.

    Comment by David B. Benson — 6 Mar 2006 @ 9:20 PM

  105. Gerald, in case David’s clarification still wasn’t quite clear:
    (numbers are hypothetical)
    We have warmed 1oC recently, absent anthropogenic influences we should have cooled .2oC, therefore the percentage of the warming would be anthropogenic is 1.2/1 or 120%.

    So it is not as ridiculous as you indicate.

    Comment by Coby — 6 Mar 2006 @ 10:22 PM

  106. Re #91,#101,#103,#104,#105.
    You speak of calculation. You can throw any figures out(which you did) and calculate. But you have not scientifically measured. You make reference to thousands of years ago. Temperatures went up and down at that time. How would they have gone up without AGW – according to your theory? Was there AGW then? Likely close to zero. So I have a hard time accepting the more than 100 percent or anywhere near that amount. With those figures you are suggesting that without AGW we would be rapidly approaching an ice age.
    My point still remains – If we went up One Degree – the percentage of that increase due to AGW has not been measured. It is being attributed(linked)by association to CO2 because the amount of CO2 has been measured as increasing

    Comment by Gerald Machnee — 7 Mar 2006 @ 12:19 AM

  107. Estimates of the net change in land carbon since the glacial maximum seem to be converging betwen a
    and a
    30 percent rise

    But, from ,”The Migrating Boreal Forest”, I notice that much of the Canadian boreal forests occured after the holocene epoch, and in previous glacial cycles, never would have appeared.

    So, this is quite confusing to me, In previous glacial epochs the rapid melt would have exposed barren tundra soils in the Northern hemisphere causing a peak in co2 rise. In our epoch, the melt was gradual enough to allow migration of large forests north.

    During the younger-dryas collapse, co2 levels were 40 ppm lower than previous cycles, and thanks to our experiment with co2 spiking, I conclude, some 12,000 years ago, a missing 60 gigatons of atmospheric carbon. The suspect is carbon sequestering in land biomass.

    Comment by Matt — 7 Mar 2006 @ 12:32 AM

  108. Gerald,

    AGW theory does not say that all warming at all times must be anthropogenic. It only states that the current warming trend is dominated by human emissions of GHG’s. Other flucuations are the results of different combinations of different forcings. If they are unknown due to lack of adequate data, that does not mean they did not exist.

    As for how much forcing comes from which factors, you might enjoy this link:

    BTW, my throw away figures were intended as a proof of concept only, because you had indicated you thought it a ridiculous notion on its face that we could cause more than 100% of a warming trend. I think they served their purpose.

    Comment by Coby — 7 Mar 2006 @ 1:16 AM

  109. The key issue about Greenland is the air which surrounds it, air is warmer so will be the surface of the ice sheet. Never mind about that + 1 C increase, it is at this time in many regions experience temperatures way above that number. I like to sympathise with those who believe that AGW is not happening, perhaps they have not felt regular +4 to +6 C monthly mean temperature anomalies, nor +30 C above daily average temperature warming, or 40 C SAT variations within a few days, all around Greenland, but I can’t. What does these temperature variations do to ice? We know what they do to mountain rock.

    Comment by wayne davidson — 7 Mar 2006 @ 1:47 AM

  110. #68 – “Stick ourselves at glacial maximum in a chaotic system” and other posts about chaos.

    Not a bad idea and also seems to be the only post with a constructive suggestion on how to use chaos as a decision making tool. Unfortunately we cannot stick ourselves anywhere until we have the power to manipulate climate. We won’t have that power for a long time (if ever) but we do have the power to change climate in an uncontrolled manner and we are forced by our infrastructure and lifestyle to use it.

    Let’s for a minute disreagard predictions that have already been realised and pretend we don’t know anything about climate. To be able to manipulate climate we need a model of how it works, the chaos advocates tell us this is impossible in a climate system because chaotic influences will invalidate any prediction. So we are lead to belive models are not worth developing without chaos, and if they are developed with chaos then they are useless random predictions. In other words there is no point in mitigation or even analysing any of the data since conclusion are no better than “random predictions”.

    The point of the models at a civilisation level is not to find the date of armmagedon or even Katrina-II, it is to put a number against a percived risk as best as is practicable (as any insurance company would do). Even if we accept that there are chaotic elements to climate change would it not be prudent to control our activities to reduce the unintended use of our power to change the current climate? And doesn’t chaos theory just increase the logic behind controlling those activities to reduce the percived risks?

    The basic argument from the chaos advocates is that the climate is unpredictable so why bother changing our activities? If they look at the logical risk implications of chaos they may find an answer to their own question. Chaos theory implies the one thing we don’t want to change is climate, our climate changing activities can be changed and are negotiable via treaties and regulations but Peak Oil may make it a mute point in the next few decades.

    Maybe I’m just too close to 50 but it seems to me the industrial revolution, like many well intended revolutions, is about to fail spectacularly. I just hope there are enough people left to start the next one.

    Comment by Alan — 7 Mar 2006 @ 5:08 AM

  111. Re # 108 – There is a related factor to CO2 – Increased condensation nucleii (which is not a GHG) which would cause increased cloud cover and consequently higher temperatures. I do not know if anyone is looking at it.

    [Response: ??? Start here. This is one of the hottest current topics in climate – gavin]

    Comment by Gerald Machnee — 7 Mar 2006 @ 10:10 AM

  112. Re Response in #111 – many studies cite aerosols as creating a cooling effect. However the point I was making was that some contributors spoke about the increase in cloud cover. My comment was addressing the reasons for the increase and a possible increase in temperature.

    [Response: This is the ‘indirect affect’, and that is generally thought of as a cooling as well. However, there are a number of different processes involved which make the net impact rather uncertain (but it is almost certainly negative). – gavin]

    Comment by Gerald Machnee — 7 Mar 2006 @ 11:21 AM

  113. Man is an intelligent squirrel, and tends to sequester carbon on land. We use oil because we have a land scarcity and need an efficient energy source to take ocean carbon and leave it on land. The atmosphere has been a transport system for us, moving ocean carbon to land, where we sequester the stuff.

    So, we adapt to the scarcity of fossil fuel by engineering photosynthesis and gaining a 10 fold increase in solar efficiency. We engineer microbes to make cellulose a viable fuel source. Now, the atmosphere is a transport mechanism between underground carbon and land carbon. Photoshynthetic scientists are moving us through a major techological advance, as they alwas have done.

    There is something innate in mammals, they collect carbon. In 300 years we will be facing an atmospheric carbon shortage. Maybe man’s destiny is to ultimately collect every bit of carbon from the oceans and from underground, bury it under a kilometer of ice while we huddle around our fusion fire at some oasis in on the equator.

    Comment by Matt — 7 Mar 2006 @ 1:04 PM

  114. Rasmus,
    It’s as much your language as your climatolgy skills I’m drawing on here.

    Wikipedia has been linked to many times here on RC presumably as a scource of reliable information. After viewing the Danish version under “Menneskeskabt drivhuseffekt” ( anthropogenic greenhouse effect)
    I have the gravest misgivings!

    Three quarters of the blurb highlights the reasons why sceptics believe the whole thing is invention or exaggeration, while there “is great uncertainty as to how large the anthropogenic effect is.”

    There is a link to Svensmarks graph in all its glory:

    Sigh! Do any of your colleagues at DMI feel a moral obligation to contribute?:

    Can Wikipedia get hijacked by minority views?

    Comment by Rick — 7 Mar 2006 @ 5:15 PM

  115. Inductive logic the Bayesian way. This is the first of a two part post. This part contains useful references and an important idea due to I.J. Good which appears rather neglected.

    E.T. Jaynes
    “Probability theory: the logic of science”
    Cambridge Univeristy PRess, 2004

    is recommended in a review as the book on Bayesian reasoning which is the ‘most fun to read’.

    J. Hawthorne, “Inductive Logic”, Stanford Encyclopedia of Philosophy, 2005.

    quickly, but thoroughly, shows most aspects of how to use Bayesian reasoning in science. Jim also e-mailed to me a site where there is a free Bayesian network program one might care to use/try:

    In Bayesian reasoning, the important concept is the ‘odds on’ aka ‘likelihood ratio’ between competing hypotheses, given the data. With hypotheses H and K with data D,

    L = p(H | D)/p(K | D)

    is the measure of how much better or worse H is in comparison to K. But it is much better to take the base 10 logarithm with units of bans and even better to take units of a tenth of a ban, called a deciban and abbreviated db. (The name ‘ban’ is due to A. Turing, 1941.) Now I.J. Good suggests that “A deciban or a half-deciban is about the smallest change in weight of evidence that is directly perceptible to human intuition.” So if

    10 log L < 0.5

    there is no perceptible advantage of hypothesis H in comparison to hypothesis K.

    [Response: Use ‘& l t ;’ for the less than sign. Otherwise it thinks it is html. – gavin]

    Comment by David B. Benson — 7 Mar 2006 @ 6:07 PM

  116. Applying some Bayesian reasoning —

    To keep the application simple, we are ignoring any background information and treating the situation as simply a sequence of
    Bernoulli trials: opening boxes one after the other to discover whether the marble inside is black or white. We are certain that there is exactly one marble in each box and it is either black or white. As Bernoulli trials, there is a number, r, which is the probability of discovering a black marble. We then have the infinitude of hypotheses H(r) for r in [0,1]. Finally, as p=1 is special, write B=H(1). We will compare all the hypotheses H(r) to B.

    The data, D, consists of opening the first 7 boxes, the wooden boxes, to discover a black marble in each one. Now clearly the probability of the data D given B is 1, p(D | B) = 1. It will be the odds on,

    L(r) = p(D | B)/p(D | H(r))

    that determines how much better the hypothesis of all black marbles is in comparison to the hypothesis of random fraction r are black. (This is the correct ratio, I said it backwards in #115.)

    For example, consider H(0.5). In this case we have r^7 = (0.5)^7 = 0.0078125 = p(D | H(0.5)). Now computing the logarithm of 1/0.0078125 and multiplying by 10,

    10 log L(0.5) is about 20 db.

    This means that hypothesis B is vastly superior to the hypothesis H(0.5).

    We now turn to those hypotheses H(r) which are indistinguishable from B under I.J. Good’s claim that a half-decibel is resolvable to the human intuition. It turns out that 98%, i.e., H(0.98), gives about 0.607 db but 99% gives about 0.294 db. So H(0.99) is neither better nor worse, under this criterion, than B. But H(0.98) is worse than B.

    Summarizing this part, after opening the first seven boxes, those made of wood, we have only a small range of hypotheses left to consider, B and those very nearby. What happens when we open the jade box?

    Under the hypothesis that all boxes have the same statistics, we are quite unlucky in finding a while marble. We had thought there was only about a 1% chance of this occuring. Another hypothesis is that the composition of the box makes a difference. In this case we specialize our previous hypotheses to apply only to wooden boxes, starting over for jade ones.

    I claim that this is exactly what scientists will do in such a situation. Of course the actual background knowledge will make a difference here. Furthermore, I claim that the hypothesis that wooden boxes and jade boxes have different values for the proportion r of black boxes is highly confirmed by the weight of the evidence, in much the same way as has already been done just for the wooden boxes.

    Comment by David B. Benson — 7 Mar 2006 @ 7:01 PM

  117. > 114: “Wikipedia has been linked to many times here on RC
    > presumably as a scource of reliable information ….”

    Was that meant to say “source” or “scourge”? (grin) Both happen.

    Wikipedia often does get hijacked; over time, given attention, it should be self-correcting, and there’s a procedure for evaluating writers, something like current editors can vote to stop taking changes from particular IP numbers proven to be malicious or misinformative, I think — it’s been much in the news lately as US Congressional staffers were abusing the process.

    Comment by Hank Roberts — 7 Mar 2006 @ 8:45 PM

  118. RE: #113. I would not rule out that scenario. In fact, I tend to think it likely.

    Comment by Steve Sadlov — 7 Mar 2006 @ 9:05 PM

  119. I sort of got into the bayesian debate, and it reminded me of a task I once performed for some government agency.

    The correct procedure to determine if the temperature curve is related to greenhouse gases is:

    Take your temperature measurements over, say 1000 years, and perform a spectral analysis to compute its linear model. Go out to some number of spectra, get the number of terms to make everyone feel happy. Then you have a linear model of temperature, and the variance of the residual white noise is the gaussian covariance of the frequency terms. (There is a reference for this somewhere).

    Now, compute the expected temperature curve from your gas law, normalize for average temperature (go back 1,000 years, zero is valid). Compute its spectra.

    Then you can ask the gaussian question, what is the probability that the spectra of your computed gas law could have have been sampled from the linear temperature model driven by white noise.

    Any other alternative hypothesis should wash out.

    Someone did this, I think, for I saw it announced with great fanfare.

    Comment by Matt — 7 Mar 2006 @ 9:07 PM

  120. Thanks DB (#115, 116); I’ll have to read that again. I should probably just take some time and try to learn Bayesian methods. My only critique of what you produced is that you should probably have r^7 x 2(because it could just as easily have been all white marbles — or maybe you should have used r^6 because once the first marble’s colour is known, you are just seeing if the rest are the same colour). Hmm, now I’m having trouble with basic probability. In any case, the calculations also don’t consider temporal autocorrelation. I think we’re assuming that each box is independent….

    Sorry to all who find this irrelevant. Perhaps this will make it up to some of you:

    This is a simple little freeware tool to do contingency analyses. It will give results equivalent to Fisher’s exact test, but you can have several rows and columns. I used it to get a p-value for the hypothesis that marble colour is not contingent on box type. I got a p-value of 0.125 (i.e., fail to reject).

    Comment by Steve Latham — 8 Mar 2006 @ 1:49 PM

  121. Re #120 —

    I am sure I did the calculations correctly. There are seven wooden boxes. Assuming Bernoulli trials does indeed mean an assumption of independence of the trials. This means that the probability of seeing seven black marbles is precisely r^7, since the trials are assumed to be independent.

    I am now going to do one more comparison of two hypotheses.
    The first hypothesis is that all wooden boxes contain black marbles and jade boxes contain white marbles. Call this hyptotheis Y. The second hypothesis, N, is that all boxes are the same, Bernoulli trials, with r=7/8 for the probability of seeing a black marble. The data D consists of 7 black and 1 white marbles. The probability of seeing this data, given Y is p(D | Y) = 1. The probability p(D | N) = (7/8)^7*(1/8) = 0.0491

    10 log(p(D | Y)/p(D | N)) is about 31 db.

    This is a large value of decibans, confirming that the weight of the evidence strongly favors hypothesis Y over N as explaining the data D.

    Translating this back to AGW, recall that boxes correspond to the last 8 times that methane concentrations were over 550 bbp as recorded in the Vostok icore core record. Black marbles refer to subsequent decrease in methane concentrations tracking orbital forcing. White marbles refer to increase in methane concentrations despite the lower global forcing. Wooden boxes are the first 7 in the record. The jade box is the Holocene. The hypothesis Y corresponds to increased methane due to human activity, essentially Ruddiman’s thesis. The hypothesis N corresponds to a probabilitistic statement that methane concentrations only track orbital forcing 0.875 of the cases. We see that Y is much the better explaination, this being AGW as opposed to ‘just happened’.

    There are, of course, an infinitude of hypotheses which could be
    compared against Y. But Ockham’s Razor encourages one not to unnecessarily add concepts. Hypothesis Y is a simple and as explainatory as can be — and I was surprised to see how much
    more so when I computed the 31 decibans.

    Comment by David B. Benson — 8 Mar 2006 @ 2:20 PM

  122. Re: #111, “There is a related factor to CO2 – Increased condensation nucleii (which is not a GHG) which would cause increased cloud cover and consequently higher temperatures. I do not know if anyone is looking at it.”

    CO2 emissions alone do not create more condensation nucleii. Other industrial and transportation-related pollution may, but water vapour cannot condense on CO2 molecules.

    What CO2 emissions do is heat up the atmosphere, which in turn heats up the oceans (at a lag and far less rapidly), which leads to greater evaporation. This causes the increase in cloud formation, which is the condensation of which you mention. This increase in cloud formation will increase the overall albedo of the planet, but also, will trap longwave radiation inside the troposphere.

    This is theorised by the IPCC in their prediction that overnight minimum temperatures will be much warmer than previous and that minimum temperatures will rise at a greater rate than daytime maximum temperatures. The reason: increased cloud cover at night. This is also the reason for the much warmer-than-normal (and possibly record-setting) December and January temperatures for areas of North Dakota and Minnesota and over much of the Canadian Prairies.

    Comment by Stephen Berg — 8 Mar 2006 @ 2:21 PM

  123. Re #122 – What I meant by related was that combustion produces nucleii in addition to CO2. That would lead to the increased minimum temperatures with more cloud forming on the nucleii.

    Comment by Gerald Machnee — 8 Mar 2006 @ 3:31 PM

  124. Re: #123, “What I meant by related was that combustion produces nucleii in addition to CO2. That would lead to the increased minimum temperatures with more cloud forming on the nucleii.”

    Possibly, but what an increase in CO2 emissions will do is increase the quantity of water vapour in the atmosphere, increasing the humidity, which will make cloud formation more likely.

    Temperatures will go up, but so will dew point temperatures. This also leads me to think that severe thunderstorms and tornadoes will likely occur, as higher Ts and Tds lend more convective energy into a system.

    Comment by Stephen Berg — 8 Mar 2006 @ 6:53 PM

  125. Re # 124 – In the first part – that is generally what I said. Re severe weather – Dr Madhav Khandekar of Environment Canada did a study on it and could not find conclusive evidence that severe weather would increase(in Canada). You may have more thnderstorms but to get severe ones you need dry and moist areas to form plus upper support. These synoptic conditions vary from year to year and would not necessarily increase in frequency.

    Comment by Gerald Machnee — 8 Mar 2006 @ 8:08 PM

  126. re 27.

    Impact Of Climate Warming On Polar Ice Sheets Confirmed

    Comment by Pat Neuman — 9 Mar 2006 @ 12:18 AM

  127. Re #126 – That is outdated. It covers to 2002 and does not take into account the Zwally study of 2005 quoted at the top of this post.

    Comment by Gerald Machnee — 9 Mar 2006 @ 9:54 AM

  128. re 127 126
    The survey was published this week in the Journal of Glaciology.

    This link has nice photos by NASA/SVS.

    Comment by Pat Neuman — 9 Mar 2006 @ 1:03 PM

  129. Re #127: Actually Zwally 2005 just covered data through 2002 and it’s the recent R+K paper in Science that discusses the rapid glacier flow of the last few years. There’s no conflict between the studies as they were measuring different things. See the original post, which places all of these studies in context, and Jay Zwally’s comment 5. (What is confusing is why Zwally 2005 is just being published now. Maybe that journal makes papers available electronically for a while before paper publication.)

    Comment by Steve Bloom — 9 Mar 2006 @ 10:07 PM

  130. For an average person who tries to follow this subject, I don’t know what to make of the data. A couple of weeks ago, there was another alarmist article about the Antarctic losing 36 cubic miles of ice per year. Yet the Antarctic is composed of over several million cubic miles of ice, is it not? In that context, how significant is the loss of 36 cubic miles of ice?

    The melting in Greenland likewise appears to be very minor compared to the total overall mass of ice. Yet articles state that Greenland’s ice could possibly melt in several hundred years. Is this good science reporting when the current data supports no such conclusion? And why are scientists themselves fostering such misconceptions?

    Comment by Paul — 10 Mar 2006 @ 5:12 PM

  131. Paul, how much calculus do you have? The rate of change is changing, and the question is — how fast is the change in the rate of change.

    That’s — for those like me who stopped just past algebra — not easy, and I agree the science journalists aren’t doing a very good job. Your posting makes clear that what your read didn’t convey the info.

    Let me try the simple summary and then let the scientists correct me (“the way to get good information on the Internet is to post what you know and await correction”).

    Snow falls and slowly gets packed down making ice. Ice builds up until it begins to flow slowly (pressure from above and warmth from the earth below). That makes a glacier, if the terrain lets it move.

    Glaciers flow, slowly at the edges, faster at the middle.

    Glaciers that flow out over cold water build up layers of ice (ice shelves).

    Ice shelves ‘push back’ and keep some limit on how fast the glacier flows out from the land.

    The ice shelves are floating on ocean water.

    Ocean water is getting warmer.

    The top of the ice caps is getting warmer, and water lakes form on top of the glaciers, water flows down through crevasses to the earth below, and makes a lubricating layer.

    Ice shelves break up and float away (happening in Antarctica, quite unexpectedly, in the last few years).

    Glaciers start to speed up. Until last November, only a few were speeding up. Now several more are speeding up, and so we have a pattern rather than a few exceptions. The pattern is that the speed of glaciers is changing.

    We don’t know how fast the change is changing — will the glaciers be moving faster next year? Will more of them be moving faster? But this was a surprise.

    Once a glacier gets moving — and it’s moving into warmer ocean water so it doesn’t make ice shelves, in fact it melts faster so there’s less ice to push back.

    The concern is that we didn’t think the ice caps and glacial ice was going to change its motion, especially not so early in the warming period we know is happening, and the ice — both in Greenland and Antarctica, both ends of the planet — has started moving faster in many places, not just a few.

    Okay, one of the glaciologists, please correct me (grin). (And please note your credentials, there are a lot of opinions but few informed ones)

    Comment by Hank Roberts — 10 Mar 2006 @ 6:20 PM

  132. Whoa, Paul. In the space of eight sentences, you’ve gone from “an average person who tries to follow” to an accusation of scientists fostering misconceptions without supporting data. And you did that by reading journalism on a brand new finding. That is fostering misconception without supporting data.

    As for the finding in the Antarctic, it is still early and yes the numbers are not that large (but you should think of it in terms of sea level equivalent, not relative to the millons of km^3 total ice). It is new however. Greenland is much more significant and it is not just the amount of mass loss it is the acceleration. So your linear extrapolation to “why worry” is not very sound. Ice sheets are complicated and not well modeled but historical sea level rises suggest once things start to move, they can move quickly.

    Comment by Coby — 10 Mar 2006 @ 7:04 PM

  133. Realistically, if this is a long term warming (and not a simple cycle in periodicity) Greenland’s ice will mostly likely take a few thousand years to completely melt away. Were that to happen, long before that point was reached, sea level would rise noticeably. But how long is long? Probably about 1000 years, realistically. Worst case scenarios are rarely realized in fact.

    [Response: Curious. You appear to be quite suspicious of very well established physics of the greenhouse effect (for instance, as implemented in GCMs), and yet completely confident about the much more poorly understood mechanisms and rates of ice sheet melting. Hmmm…. -gavin]

    Comment by Steve Sadlov — 10 Mar 2006 @ 8:50 PM

  134. Thank you for your comments.
    Comment #131
    Hank, I can appreciate that the rate of change is changing, but that still does not address the issue. In the case of the Antarctic, we have recently been informed that 36 cubic miles of ice has melted. Out of how many million cubic miles of ice? To a layperson (me), that appears completely insignificant.

    Comment #132
    Coby, some scientists have been fostering misconceptions. The rate of increase in the ice melt in Greenland is a concern, yes, but there is no good data for some scientists to contend that Greenland’s ice could be gone in a few hundred years.

    Comment by Paul — 10 Mar 2006 @ 9:38 PM

  135. re 134.

    The atmosphere is becoming more humid, increasing condensation. The significance of latent heat for snowmelt has been described by Dunne and Leopold (1978):

    â??If water from moist air condenses on a snowpack, 590 calories of heat are released by each gram of condensate. This is enough energy to melt approximately 7.5 gm of ice, which when added to the condensate yields a total of 8.5 gm of potential runoffâ??.
    Dunne, T., Leopold, L.B. (1978) Water in Environmental Planning.

    Added heat from condensation applies to ice fields, glaciers, sea ice and seasonal snow depths in mid-high latitudes. Snow melts quicker with higher dewpoints, increasing runoff and flooding in the Upper Midwest and other areas.

    Comment by Pat Neuman — 10 Mar 2006 @ 10:19 PM

  136. RE #135 – Your study applied to a limited area(Minnesota).You state “Added heat from condensation applies to ice fields, glaciers, sea ice and seasonal snow deplths in mid-hogh latitudes” If you are now looking at the global picture you have to account for the latent energy used in melting and evaporation of the ice (670 cal/gram) to get that heat of condensation. If you mean that moisture is increasing globally, it had to use up the latent heat to get there.

    Comment by Gerald Machnee — 10 Mar 2006 @ 11:26 PM

  137. Paul, ’til someone who actually studies the area answers, my pointers just as a regular reader.

    The ice that’s melting is melting from underneath — what disappears is the bottom of floating ice shelves, because the ocean water is warmer. Eventually the ice shelf becomes unstable and breaks apart.

    Possibly there is a level of CO2 that toggles the polar ice — either growing — or melting:

    Much of the Antarctic ice is displacing ocean water, because the solid land surface is well below current sea level.
    Compare the topography — see how little solid land is above sea level (compare this to any contemporary picture of Antarctica showing the extent of the ice cap:

    Comment by Hank Roberts — 11 Mar 2006 @ 12:38 AM

  138. Oh, and (forgive me RC hosts for drifting further from the Greenland thread — I realize this is going way off topic)

    From the bottom of the first link I posted, this:
    gives a picture of the current ice extent, with links to detail on all the ice shelves in the Antarctic.

    Comment by Hank Roberts — 11 Mar 2006 @ 12:47 AM

  139. Re: #136, “If you are now looking at the global picture you have to account for the latent energy used in melting and evaporation of the ice (670 cal/gram) to get that heat of condensation. If you mean that moisture is increasing globally, it had to use up the latent heat to get there.”

    Yes. This is true. However, with the latent heat energy exhausted by the evaporation of water and melting of ice, the global atmospheric temperature continues to rise at an increasing rate. This means an accelerating rate of evaporation and melting is likely as temperature and latent heat continue to rise. There is an imbalance there, and these environments are equilibrium-seekers, so one rate will accelerate to meet the other.

    Comment by Stephen Berg — 11 Mar 2006 @ 5:40 PM

  140. re 136.

    On February 23, 2006, Luna Leopold died at the age of 90. Luna was a vital force, a man of extraordinary creativity and originality, whose passion about science and the natural world permeated all he did.

    Comment by Pat Neuman — 11 Mar 2006 @ 7:54 PM

  141. The different blogs tend to converge so I thought I would blog here : I hope you dont mind.

    1. The first reference is to a report on carbon levels over the poles which is worrying to say the least.,,1729256,00.html

    2. There was a reference by Mr Benson to Scottish research on “adaptation” for farmers. Does he have any references for this please? I was talking to my daughter last night who farms with her family in South West France and is also one of the few remaining white farmers in Zimbabwe and we were discussing the impact of climate change on farming, world trade in agricultural products and the security of food supplies. I didnt know of any work done on “adaptation” and wonder if others may be able to add to Mr Benson’s comments.

    3. Just to cheer everyone up the following reference is to a letter in The Guardian,,1728721,00.html

    You will note that it is signed by 8 MPs. What were the other 600 odd doing then?

    Great website. Keep going and don’t weaken.

    Comment by Eachran — 12 Mar 2006 @ 8:46 AM

  142. Hosts — the forum software here isn’t recognizing the double comma in those Guardian URLs Eachran posted above. Meanwhile, for working links see:

    The Mount Zeppelin station is the northernmost settlement and measures a lot of gases; they are reporting increasing rates of change for CO2 and methane.

    Comment by Hank Roberts — 12 Mar 2006 @ 1:10 PM

  143. It seems Hank is the only one still focussing on the actual post. As a glaciologist who has worked on Jakobshavns Glacier and Pine Island Glacier, it is evident why one has an ice shelf and the other does not. Ice shelves exist only in areas where ablation is small and an accumulation zone extends to the edge of the glacier system. Ice shelves do not survive once surface melting and an ablation zone develops. The Larsen Ice Shelf was thinning already, as noted in the links of comment 137, however, I agree with the first comment after the paper on the link page, and that is thinning did not lead to the loss of the ice shelf alone. The more important component was the first noted development of substantial melting on the surface of the ice shelf. Ice shelves do not endure simply by ice flowing from feeder glaciers and spreading out over a portion of the ocean, they need an accumulating snowpack to survive the summer season on their surface.

    Comment by Mauri Pelto — 12 Mar 2006 @ 3:46 PM

  144. Re #130, #134 — Paul asks if it is responsible for a scientist to state that the Greenland ice gap “could possibly” melt in a few centuries. This question deserves an answer. I will try, although I am no expert in any aspect of climatology.

    I’m going to treat this as a matter of sea stand. I will treat the melting of the Greenland ice gap as the equivalent of an increase in sea stand of 5 meters. (Experts please correct if this is badly wrong!) So the question might be posed as asking if it is responsible of a scientist to state that the sea stand could possibly rise 5 meters in a few hundred years.

    One way to determine this is to look at periods in the past records when sea stands have risen by 5 meters or more within a few centuries. Looking at Figure 6.1 on page 98 of F. Oldfield’s “Enviromental change: key issues and alternative approaches” we discover a record of sea stand versus time from 26,000 to 10,000 years ago. From 14,500 to 14,000 years ago occured an event marked MPW-1A. During this interval the sea stand rose about 25 meters. From this same graph, after the end of the Younger Dryas 11,500 years ago, the sea stand rose at least 10 meters in about 500 years.

    Given this has happened in the past, is a statement of “could possibly” a responsible statement? Note this is not a statement with a probability attached. The statement simply says that such an event, rise of sea stand of 5 meters in a few hundred years is not impossible. Given the historical facts listed above, what would you say?

    Comment by David B. Benson — 12 Mar 2006 @ 5:34 PM

  145. 144. I think that you are correct.

    The problem is being the party pooper whether politician or scientist. You can imagine the excuse :

    Well I know that I have been plugging growth as the panancea….but….anyone can make a mistake….cant they?


    There is a 95% chance of everything being OK. OK?…OK maybe?

    I dont like the odds or the timescale either and as a non-expert I am impressed by people like Mr Hansen (and the people who run this blog) who alert us all to the possibility of catastrophic collapse – of ice sheets but also of civilisation.

    What to do? Well I cant say that I am impressed by 8 MPs in the UK asking us all to be a bit more attentive to climate change but I am impressed by scientists who try doggedly to get to the “truth”.

    I am curious to know if the the added carbon in the atmosphere at the North Pole implies a faster melting of the Greenland sheet. Just so I know how long I have to build my Ark in the back garden.

    Having read the IPCC WG2 and 3 I am curious also to know the up-date : I suspect it will make ugly reading.

    Comment by Eachran — 12 Mar 2006 @ 6:21 PM

  146. The carbon in the recent story is carbon dioxide and methane; the high levels are local (not yet averaged out by mixing worldwide) around that far north sampling site because it’s wintertime (not much photosynthesis using it up as it’s released). Where it’s coming from and how fast in that local area is the issue (is there more coming out of peat bogs for example).

    The report — I haven’t found anything besides press stories — is from the same lab that gave us the report of increased gas from peat and permafrost five years or so ago, if I recall correctly.

    They’re sampling at the far north extreme of human settlement — as far from local human sources as possible.

    Comment by Hank Roberts — 12 Mar 2006 @ 6:45 PM

  147. Re #145 – **I am curious to know if the the added carbon in the atmosphere at the North Pole implies a faster melting of the Greenland sheet. Just so I know how long I have to build my Ark in the back garden.**
    If you read the introduction at the top of this post, you will see studies that discuss accelerating of the glacier, increased melting at the leading edges, and increased accumulation in the middle of Greenland. They are having a problem calculating which is faster – melting the glacier at the leading edges or actually causing it to accumulate faster in the middle. Do not worry about the ark – it will take too long to melt. But I would be more concerned about pollutants in the air if they do not clean up industry.

    Comment by Gerald Machnee — 12 Mar 2006 @ 8:21 PM

  148. Re #146: There was an “exclusive” story a few months ago in the Independent (UK) that claimed the Mauna Loa (Kea? – I can’t keep this straight) CO2 readings for 2005 (not yet officially released, which is interesting) had jumped considerably. If I recall right the article speculated that the cause might have been a big increase in peat burning in Indonesia. Maybe, and maybe there’s a local explantion for what’s going on in the Arctic, but OTOH the combination of the two reports causes one to wonder.

    Comment by Steve Bloom — 12 Mar 2006 @ 10:55 PM

  149. Re #147: While it’s true that the dynamic melting is unlikely to proceed quickly enough to have a big effect on coastal regions of the First World during the next 20 to 30 years, Gerald’s response seems to assume that we can discount to zero impacts on future generations. I find that morally objectionable.

    On the science, IMHO Gerald misinterprets the post. While the exact current balance of ice loss vs. snow accumulation is interesting, the concern with Greenland is that as things continue to warm the rapid growth of the ice loss will quickly overwhelm the snow accumulation such that the rate of ice loss will increase vastly. Exactly how quickly the collapse could really occur has yet to be established, but the signs (the recent speed-up of glaciers in southern Greenland and the apparent progress of this speed-up into the north, plus the equally rapid growth in the surface melt zone) are very bad.

    The much greater size of the Antarctic makes it less vilnerable to these effects in the short term, but the fact that the Greenland-sized West Antarctic ice sheet is largely grounded below sea level and has a clearer route to the sea than Greenland potentially makes it prone to collapse in a similar time frame.

    I have yet to hear a scientist working on these issues say, e.g., we can categorically exclude the possibility that Greenland amd/or the WAIS might substantially collapse within a century or so. That makes me very nervous indeed since while we night hope to adapt reasonably to such melting on a scale of centuries, I doubt that would be true if it happened more quickly. A glance at topographic coastal maps to see the effect of a 10-15 meter sea level rise makes that point very clear.

    Comment by Steve Bloom — 12 Mar 2006 @ 11:33 PM

  150. Re #143: I wanted to take the opportunity to thank Mauri and the other scientists, climate amd non-climate, who participate in the comments on this site. It takes part of the load off the RC authors, which I know they appreciate since this is a volunteer effort, and adds further valuable perspective.

    Comment by Steve Bloom — 12 Mar 2006 @ 11:53 PM

  151. Re # 149 – **On the science, IMHO Gerald misinterprets the post. **
    I do not believe that I have misrepresented the post. There is no conclusion or proof of what will happen. Several studies are quoted.
    **Gerald’s response seems to assume that we can discount to zero impacts on future generations.**
    I have not said the impact is zero, but I have said that before we have significant rise we will pollute ourselves, among the other things not discussed on this blog.
    **Exactly how quickly the collapse could really occur has yet to be established, but the signs (the recent speed-up of glaciers in southern Greenland and the apparent progress of this speed-up into the north, plus the equally rapid growth in the surface melt zone) are very bad.**
    And I do not buy the alarmist collapse of the Greenland Ice Cap. Here is where I indicate that scientists are not sure if warming is actually contributing to an increase in ice mass through more precipitation as warmer air holds more moisture.
    **I have yet to hear a scientist working on these issues say, e.g., we can categorically exclude the possibility that Greenland amd/or the WAIS might substantially collapse within a century or so.**
    I do not believe that too many scientists actually believe that Greenland would see enough melting to even raise the sea level even half a metre in a century. I still say “let’s work on the pollution”

    Comment by Gerald Machnee — 13 Mar 2006 @ 1:19 AM

  152. Re #151: I think you’re being a little evasive, but in any case there’s no point in you and I continuing to go around on these issues. However, I am curious as to what you personally are doing about air pollution. Details, please.

    Comment by Steve Bloom — 13 Mar 2006 @ 4:40 AM

  153. 146 onwards. Thanks to all and yes I have read the master post at the top.

    My point was more to do with hotspots. As with preferring ozone holes to steer clear of populated areas I wondered if having a carbon hotspot at one pole was very healthy for us : it cant make the current small (? and rate of change uncertain) negative mass balance for the Greenland sheet any better.

    Ozone holes, I understand, are having significant problems repairing themselves and for carbon hotspots I havent a clue.

    This seems to me like a really technical question to do with source(s), sinks, mixing or lack of it in the atmosphere and no doubt other issues.

    [Response:CO2 in the atmosphere is well mixed. It doesn’t matter where you add it – William]

    Comment by Eachran — 13 Mar 2006 @ 4:55 AM

  154. Thanks William but your answer does beg some questions.

    For example, you refer to CO2 but not methane : does that matter?

    For example, if I am to take Hank’s 146 comment then it will be only a matter of time (how long?) before the carbon is dispersed around the globe or absorbed or both. However I cant really believe that the Swedes would report on carbon levels which are that innocuous.

    If on the other hand the reported carbon levels are not local then what are the implications for that?

    For Gerald, I am now going to go stone wall building and leave the Ark for another day. Stone wall building has more Zen attached but it is very exhausting.

    Comment by Eachran — 13 Mar 2006 @ 7:46 AM

  155. Methane is also well mixed in the atmosphere. The only greenhouse gas that varies in concentration is water vapor, which we only affect indirectly. The implication is that local emissions of greenhouse gases have a global effect.

    [Response: Not quite true, ozone is also a GHG, is very heterogeneous and is an important forcing that is mostly driven by local emissions (of ozone precursors like NOx, VOCs, CO etc.). – gavin]

    Comment by Blair Dowden — 13 Mar 2006 @ 8:39 AM

  156. Re # 152 – Evasive? Not sure, but I do not accept everything I read without data.
    Pollution – Well, I worked for the gov – they do not listen, so my message is not getting thru. They “approved” Kyoto, but are doing nothing. They falsify information(will not go into details).
    Me – drive fuel efficient vehicle, Electical heating in house – insulated long ago to well above new standards – beats gas heating. That is enough.

    Comment by Gerald Machnee — 13 Mar 2006 @ 9:48 AM

  157. Re #156: Ah. So, broadly speaking, let others (me, e.g.) work on the air pollution problem while you spend your spare time on the internet developing arguments against solving global warming. Fair enough.

    Comment by Steve Bloom — 13 Mar 2006 @ 1:27 PM

  158. Re #144 — Correcting the Greenland ice cap sea stand equivalent.
    According to T.M. Cronin in “Principles of Paleoclimatology”, page 30, the rise, should it all melt, would be 7.4 meters.

    Comment by David B. Benson — 13 Mar 2006 @ 2:35 PM

  159. Re #156, #157 – If you think that only getting rid of CO2 will solve global warming, you are dreaming. Look at the history of temperature fluctuations over the past thousands of years. There is more to the variation than CO2. Melting Ice Caps and rising sea levels are only a possibility – pollution is here now. My son is in Japan where people wear face masks on the street. California had(and still has some) a problem, so they imposed stronger standards for cars. It is time to go much farther. If we develop the technology to clean up pollution (in land, sea, air, and food), there will be related technologies which will also take care of CO2.
    If you only talk CO2, there is less chance of a gov response. The last Canadian Minister of the Environment was fron Victoria, British Columbia. His own city has been spewing raw sewage into the Strait for years.
    The new government under Stephen Harper in their campaign indicated they would redo Kyoto into a workable program. We will see if they carry it out, but we can try a test – write to the minister and see if she responds to our communications more than the last one. I am doing that.

    Comment by Gerald Machnee — 13 Mar 2006 @ 3:53 PM

  160. RE 157, 159:

    Gerald has a good point that needs to be contextualized. It is absolutely true that – implicit in Gerald’s comments – is that human land use/landcover (LU/LC)changes have impacted the environment. China has started their dust storms this year and the cloud should be in Japan soon (if it isn’t now). And I moved from Sacramento, CA because I couldn’t take the air pollution any more.

    But focusing on LU/LC changes or short-term air pollution concerns shouldn’t dismiss our focus on CO2 – the argument in 159 implies the two are separable. They are not.



    Comment by Dano — 13 Mar 2006 @ 4:55 PM

  161. Trying to have a qualitative understanding of the glacier processes.

    A frequent mention is made of lubrication by meltwater at the base of a glacier, as well as of growing pressure from above due to increasing snowfall. There are other factors as well.

    I do not know exactly how the satellites measure the extent of summer melt in Greenland. Anyway, a major change seems to be underway, reflected in the large change in this parameter. Some related components I could identify are:

    1) Change in snow surface layer properties and in the process that converts snow into ice. This might impact the measurements (sensor calibration), for instance. This forms mainly slush that do not flow.

    2) In places, meltwater may flow and form pools, in extreme cases even lakes that do not freeze fully during the winter season. The terrain could get more even than before. A small part of meltwater may even flow into the ocean.

    3) Summer meltwater fills existing cracks in the ice, then re-freezes there at some depth as the interior of the glacier is well below zero temperature. This is heat transport, as the water latent heat is released the glacier inside temperature increases.

    4. Re-freezing also generates tremendous mechanical strains. Water expands as it freezes. Old cracks close, but new ones are formed and cracks deeper down are widened. (Incidentally, this process was sometime used in stone quarries. A row of holes was drilled, filled with water and the forming ice cracked the granite. In nature it can be observed on the slopes of fells, where layered sedimentary rock continues to be broken into stone flows and cascades. Maybe there is an analogy to the flowing glaciers?)

    One might propose that the coastal glaciers now get broken into smaller blocks as these processes get stronger, which would facilitate the flow. This also would impact the tongues extending into the ocean. Icebergs would then break free easier than before, but would have a bit smaller volumes.

    Maybe these phenomena are included somehow in the models, though it seems to me that they are quite difficult to quantify in any detail.


    Comment by Pekka Kostamo — 16 Mar 2006 @ 12:29 AM

  162. Re #161: Based on what I know, I think some of what you mention is correct but some is not. There are papers referenced in comments 5 and 11 that would be worth a look. The Journal of Glaciology articles become public after a time, so those may be public access by now. Try Google Scholar for public access versions of the others. You might also try Richard Alley’s site to see if he has any material posted.

    Comment by Steve Bloom — 22 Mar 2006 @ 6:01 AM

  163. Looking much deeper below the surface:

    Scientists Use Satellites to Detect Deep-Ocean Whirlpools

    Xiao-Hai Yan (seated) and Young-Heon Jo

    Xiao-Hai Yan (seated), Mary A. S. Lighthipe Professor of Marine Studies at the University of Delaware, and postdoctoral researcher Young-Heon Jo have detected deep-ocean whirlpools called “Meddies” using a new satellite-based technique they developed with researchers at NASA and the Ocean University of China. press release, 2:00 p.m. Eastern, March 20, 2006

    Comment by Hank Roberts — 23 Mar 2006 @ 8:59 PM

  164. Just noticed Arctic, Antarctic Melting May Raise Sea Levels Faster than Expected , a press release on a paper from NCAR. I haven’t read the paper yet. I imagine I’ll need help putting it in context when I do read it …

    Comment by llewelly — 24 Mar 2006 @ 12:29 AM

  165. Post 164

    Is it the same as today’s Guardian report?

    Doesnt look too good for my grandchildren.

    Comment by Eachran — 24 Mar 2006 @ 5:16 AM

  166. Re 165: Yes. It seems most major news organizations have picked it up.

    Comment by llewelly — 24 Mar 2006 @ 5:42 AM

  167. This is getting more worst case Hansenian by the week.

    It doesnt seem to me that our poor world has many options other than stopping consumption today.

    I know that William and the rest like to use the word “septik” but it looks more like stumblebum to me.

    Comment by Eachran — 24 Mar 2006 @ 5:52 AM

  168. The Guardian article was confusing: It seems to mix up global temperature rises and the higher Arctic ones. It suggests that temperatures during the Eemian were up to 5 degrees C higher than today – I thought they were only slightly above today’s. Even the NCAR report speaks of a possibility of 3-4 degrees C Arctic warming by 2100. On the other hand, NASA GISS figures show that temperatures in most of the Arctic were already 1.5-3.5 degrees C above the 1950-1980 baseline.

    Could anybody who has read the paper clarify what it says? What levels of Arctic warming and global warming are linked to changes as large as in the Eemian? Many thanks!

    Almuth Ernsting

    [Response: I haven’t read the paper(s). But I believe that Arctic temperatures were supposed to swing more than global ones, so 3-4 oC in the Arctic for the Eemian is possible, though I would have thought a bit on the high side – William]

    Comment by Almuth Ernsting — 24 Mar 2006 @ 3:56 PM

  169. I have been participating and attending glaciology meetings for 25 years. It is common understanding based on ice sheet dynamics that neither the East Antarctic Ice Sheet or the Greenland Ice Sheet can collapse quickly. They do not have the ability to undergo a large calving retreat, because of basal topography. The ice sheets are grounded and most of the retreat would have to come from in situ, ie. slow, melting. Each does have important outlet glaciers, which could experience a calving retreat, but this is not majority of the ice sheet margin. Again having worked on Pine Island and Jakobshavns Glacier I am very concerned by the substantail acceleration. But be careful of considering a rapid collapse of the Greenland Ice Sheet. Only the West Antarctic Ice Sheet is capable of rapid collapse.

    Comment by Mauri Pelto — 24 Mar 2006 @ 5:04 PM

  170. Maurio, wouldn’t the “icequakes” — which would have been well known if they’d been happening all along — suggest more cracks and crevices, and so more water flow, and so more heat transfer, and so more rapid melting all of a sudden? Or is there nothing new here to add to the common understanding from the past 25 years?

    If the “icequakes” are novel in the seismic record, what difference do they make, are there any comparable sites where icequakes have long been documented and aren’t increasing?

    Comment by Hank Roberts — 24 Mar 2006 @ 5:21 PM

  171. Maurio, I’m reading comments at New Scientist, here, that say the Greenland ice sheet is at risk now despite the fact that the ice is, as you say, “grounded” (compared to the Antarctic grounded ice where the surface is not melting).

    Do you disagree with that distinction? It’s new, not part of the 25 year history of studying this.

    Quoting from here:

    “… analysed glacial seismic records back to 1993, they found a striking increase in the number of quakes recorded in recent years. All 136 of the best-documented slips were traced to glaciated valleys draining the main Greenland ice sheet. A handful of others occurred in Alaskan glaciers or on Antarctica.

    Ekström reports that quakes ranged from six to 15 per year from 1993 to 2002, then jumped to 20 in 2003, 23 in 2004, and 32 in the first 10 months of 2005 � matching an increase in Greenland temperatures.

    The finding adds to evidence that the Greenland ice sheet is far more vulnerable to temperature increases than had been thought. Models that treated glaciers like giant ice cubes had predicted very slow melting. But recent studies of Greenland glaciers have shown much faster effects when meltwater causes glaciers to slip easily over rock.

    “Within a few years after temperature warms, you get a big increase in discharge,” says Ian Joughin of the polar science center at the University of Washington in Seattle, US. “If temperature rises two or three degrees in Greenland, things are going to start falling apart,” Joughin told New Scientist. Antarctica is not as sensitive to rising air temperature because it is too cold for surface melting, which accounts for about half the mass lost from the Greenland ice sheet.”

    Comment by Hank Roberts — 25 Mar 2006 @ 2:57 PM

  172. Better cite and more links:

    Comment by Hank Roberts — 25 Mar 2006 @ 3:12 PM

  173. Some good discussion (and good answers to questions) here, on the general melting-ice-fast-change simulations:

    (references to NASA, someone here has probably already discussed this and I’ve forgotten where)

    Comment by Hank Roberts — 25 Mar 2006 @ 8:32 PM

  174. […] Antarctica, the total volume of ice is receding in Greenland. Further, it’s doing so at nearly twice the pace previously though to be occuring. We […]

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  175. […] (2) […]

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