175 Responses to “The Greenland Ice”

1. Chip Knappenberger Says:
   2 March 2006 at 11:33 AM

   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]

2. Ana Unruh Cohen Says:
   2 March 2006 at 11:54 AM

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

3. Mauri S. Pelto Says:
   2 March 2006 at 12:08 PM

   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.

4. Lynn Vincentnathan Says:
   2 March 2006 at 1:53 PM

   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?

5. Jay Zwally Says:
   2 March 2006 at 1:57 PM

   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]

6. smyyga Says:
   2 March 2006 at 2:15 PM

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

   http://earth.esa.int/workshops/fringe2005/participants/698/pres_698_Rignot.ppt_files/frame.htm

7. Steve Bloom Says:
   2 March 2006 at 3:13 PM

   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.

8. Steve Bloom Says:
   2 March 2006 at 3:18 PM

   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?

9. pete best Says:
   2 March 2006 at 4:15 PM

   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]

10. Ben Coombes Says:
    2 March 2006 at 5:37 PM

    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?

11. Mauri Pelto Says:
    2 March 2006 at 5:39 PM

    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.

12. pete best Says:
    2 March 2006 at 6:44 PM

    I want someone to explain to me then (if it is true of course) why tropical waters have become saltier and temperate waters fresher.http://www.whoi.edu/mr/pr.do?id=897

    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.

13. Nick Barnes Says:
    2 March 2006 at 6:52 PM

    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]

14. Ferdinand Engelbeen Says:
    2 March 2006 at 7:48 PM

    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]

15. Timothy Says:
    2 March 2006 at 8:01 PM

    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.

16. Mark Chandler Says:
    2 March 2006 at 9:37 PM

    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: http://edgcm.columbia.edu/outreach/exercises/greenland.html

    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.

17. wayne davidson Says:
    3 March 2006 at 12:47 AM

    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.

18. Steve Bloom Says:
    3 March 2006 at 3:21 AM

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

19. Eachran Says:
    3 March 2006 at 7:03 AM

    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!

20. Mauri Pelto Says:
    3 March 2006 at 9:49 AM

    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.

21. John Finn Says:
    3 March 2006 at 11:07 AM

    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.

22. Pete Best Says:
    3 March 2006 at 11:24 AM

    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 ?

23. Chip Knappenberger Says:
    3 March 2006 at 12:06 PM

    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.

24. Ferdinand Engelbeen Says:
    3 March 2006 at 12:14 PM

    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).

25. Dano Says:
    3 March 2006 at 2:56 PM

    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.

    Best,

    D

26. Steve Sadlov Says:
    3 March 2006 at 3:11 PM

    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.

27. Lynn Vincentnathan Says:
    3 March 2006 at 3:32 PM

    How does the new finding that Antarctic is losing ice mass fit here? See: http://www.sciencemag.org/cgi/content/abstract/1123785v1?etoc
    & http://www.climateark.org/articles/reader.asp?linkid=53386

    [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?

28. Gerald Machnee Says:
    3 March 2006 at 3:35 PM

    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.

29. Mauri Pelto Says:
    3 March 2006 at 4:08 PM

    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.

30. Dano Says:
    3 March 2006 at 4:31 PM

    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.

    Best,

    D

31. Richard Ordway Says:
    3 March 2006 at 5:02 PM

    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.

32. Tom Cecere Says:
    3 March 2006 at 5:32 PM

    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?

33. Ferdinand Engelbeen Says:
    3 March 2006 at 6:20 PM

    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…

34. Ferdinand Engelbeen Says:
    3 March 2006 at 6:42 PM

    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.

35. Ike Solem Says:
    3 March 2006 at 8:15 PM

    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.

36. Mauri Pelto Says:
    3 March 2006 at 8:48 PM

    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.

37. Ian Says:
    3 March 2006 at 10:04 PM

    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.

38. Steve Bloom Says:
    3 March 2006 at 11:35 PM

    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”?

39. Tony Knudson Says:
    4 March 2006 at 12:23 AM

    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.

40. Steve Bloom Says:
    4 March 2006 at 1:09 AM

    Re #39: It’s not an ad hom given the extensive evidence. I suggest starting with the narrative discussion here. Other useful pages are http://info-pollution.com/warming.htm (essentially a links page) and http://www.scottchurchimages.com/enviro/ccskeptics.asp . 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.

41. Coby Says:
    4 March 2006 at 1:31 AM

    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.

42. Coby Says:
    4 March 2006 at 1:34 AM

    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.

    http://illconsidered.blogspot.com/2006/02/there-is-no-consensus.html

43. Ian Says:
    4 March 2006 at 2:06 AM

    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 http://www.grida.no/climate/ipcc_tar/wg1/413.htm; or perhaps http://www.realclimate.org/index.php?p=129. 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: http://en.wikipedia.org/wiki/Image:Glacier_Mass_Balance_Map.png - William]

    [Response: Wahl and Ammann (in press)]

44. Ian Says:
    4 March 2006 at 2:23 AM

    #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.

45. Hank Roberts Says:
    4 March 2006 at 3:29 AM

    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. …
    www.exxonsecrets.org/

46. John L. McCormick Says:
    4 March 2006 at 10:05 AM

    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 –

    http://www.glaciers.pdx.edu/fountain/MyPapers/Fountain-Walder1998.pdf

    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

47. Lawrence McLean Says:
    4 March 2006 at 11:25 AM

    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: http://www.duluthsuperior.com/mld/duluthsuperior/13995365.htm
    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.

48. Matt Says:
    4 March 2006 at 2:18 PM

    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.

49. Randall Simpson Says:
    4 March 2006 at 2:20 PM

    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]

50. llewelly Says:
    4 March 2006 at 2:27 PM

    Re 44, Ian:

    Please read http://www.ucsusa.org/publications/greentips/

    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 www.ipcc.ch, 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.

51. Hank Roberts Says:
    4 March 2006 at 2:28 PM

    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.
    _______________________
    * http://www.hyphenologist.co.uk/killfile/

52. pete best Says:
    4 March 2006 at 2:42 PM

    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 ?

53. Coby Says:
    4 March 2006 at 3:35 PM

    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:
    http://illconsidered.blogspot.com/2006/02/there-is-no-consensus.html

    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.

54. David B. Benson Says:
    4 March 2006 at 3:43 PM

    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”

55. grundt Says:
    4 March 2006 at 4:29 PM

    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.

56. Ian Says:
    4 March 2006 at 5:01 PM

    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 http://en.wikipedia.org/wiki/Greenhouse_gas - William ]

57. Ian Says:
    4 March 2006 at 5:05 PM

    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.

    cheers

58. Ian Says:
    4 March 2006 at 5:22 PM

    #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).

59. Blair Dowden Says:
    4 March 2006 at 6:06 PM

    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.

60. Ian Says:
    4 March 2006 at 6:27 PM

    #56 William — Specifically I am thinking of this graph — http://cdiac.esd.ornl.gov/trends/co2/graphics/mlo145e_thrudc04.pdf and those like it i.e. the actually measured increase of CO2 in the atmosphere.

61. Ian Says:
    4 March 2006 at 6:35 PM

    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.

62. Don Baccus Says:
    4 March 2006 at 7:08 PM

    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 …

63. Mikel Marinelarena Says:
    4 March 2006 at 10:20 PM

    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.

64. Steve Bloom Says:
    4 March 2006 at 10:35 PM

    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.

65. Gerald Machnee Says:
    4 March 2006 at 10:47 PM

    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.

66. Steve Bloom Says:
    4 March 2006 at 11:04 PM

    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.

67. Matt Says:
    4 March 2006 at 11:21 PM

    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.

68. Steve Bloom Says:
    4 March 2006 at 11:22 PM

    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.

69. Randall Simpson Says:
    5 March 2006 at 1:02 AM

    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.

70. Matt Says:
    5 March 2006 at 2:38 AM

    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.

71. Ian Says:
    5 March 2006 at 3:11 AM

    #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?

72. Pat Neuman Says:
    5 March 2006 at 8:09 AM

    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.

73. Alex Says:
    5 March 2006 at 10:06 AM

    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?

74. Gerald Machnee Says:
    5 March 2006 at 10:22 AM

    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.

75. Pat Neuman Says:
    5 March 2006 at 12:03 PM

    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.

    Gerald,

    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!

76. Blair Dowden Says:
    5 March 2006 at 12:32 PM

    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?

77. Pat Neuman Says:
    5 March 2006 at 1:03 PM

    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.”
    http://www.palmod.uni-bremen.de/FB5/geochron/Robert/RPSabstr.html

78. Hank Roberts Says:
    5 March 2006 at 1:38 PM

    Today’s Doonesbury cartoon:
    http://images.ucomics.com/comics/db/2006/db060305.gif

79. Pat Neuman Says:
    5 March 2006 at 2:39 PM

    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.).

80. Armand MacMurray Says:
    5 March 2006 at 5:49 PM

    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]

81. Pat Neuman Says:
    5 March 2006 at 6:09 PM

    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. …
    http://www.terradaily.com/reports/Ancient_Climate_Studies_Suggest_Earth_On_Fast_Track_To_Global_Warming.html

82. Blair Dowden Says:
    5 March 2006 at 9:51 PM

    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.

83. Eli Rabett Says:
    6 March 2006 at 12:28 AM

    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 http://www8.nationalacademies.org/cp/meetingview.aspx?MeetingID=1199&MeetingNo=1

    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.

84. Matt Says:
    6 March 2006 at 3:25 AM

    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?

85. Andrew Dodds Says:
    6 March 2006 at 4:27 AM

    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.

86. PHEaston Says:
    6 March 2006 at 8:46 AM

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

87. Chip Knappenberger Says:
    6 March 2006 at 12:14 PM

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

    Steve,

    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!

    -Chip

    [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]

88. Matt Says:
    6 March 2006 at 2:03 PM

    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: http://www.peakoil.org/ 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.

89. Dano Says:
    6 March 2006 at 2:30 PM

    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.

    Best,

    D

90. Steve Bloom Says:
    6 March 2006 at 3:18 PM

    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.

91. David B. Benson Says:
    6 March 2006 at 3:51 PM

    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.

92. Chip Knappenberger Says:
    6 March 2006 at 3:57 PM

    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!

    -Chip

93. Hank Roberts Says:
    6 March 2006 at 4:46 PM

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

94. Dano Says:
    6 March 2006 at 4:49 PM

    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…

    Best,

    D

95. Steve Sadlov Says:
    6 March 2006 at 5:10 PM

    #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.

96. Steve Sadlov Says:
    6 March 2006 at 5:13 PM

    #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.

97. Armand MacMurray Says:
    6 March 2006 at 5:27 PM

    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).

98. Peter wright Says:
    6 March 2006 at 6:01 PM

    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 another.eg 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
    Thankyou.
    Peter.

    [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]

99. Gerald Machnee Says:
    6 March 2006 at 6:09 PM

    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?

100. Dano Says:
     6 March 2006 at 6:16 PM

     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.

     Best,

     D

101. David B. Benson Says:
     6 March 2006 at 6:28 PM

     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%”.

102. Matt Says:
     6 March 2006 at 7:51 PM

     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%.

103. Steve Latham Says:
     6 March 2006 at 9:13 PM

     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.

104. David B. Benson Says:
     6 March 2006 at 9:20 PM

     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.

105. Coby Says:
     6 March 2006 at 10:22 PM

     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.

106. Gerald Machnee Says:
     7 March 2006 at 12:19 AM

     Re #91,#101,#103,#104