RSS feed for comments on this post.

  1. Is it possible to to estimate a probability density function of the likelihood of the west antarctic ice shelf melting as a function of global temperature increase from climate change? Is it possible to do the same thing for Greenland? I suspect that this would have a significant impact on the expected social cost of carbon.

    Comment by Peter Wood — 12 Jun 2008 @ 7:17 AM

  2. I’m confused. It’s an interesting subject, but this article could do with proof-reading – at several points there seem to be missing clauses and similar problems – and some of the things written seem unclear. For example, is WIS exceptional? If not, why say that “They further show that drainage of melt ponds into crevasses were of no relevance for the break-up at WIS. On WIS the evolution of failure zones is associated with ice rises” [but why?], but also “The mechanisms for ice shelf thinning include basal melting, meltwater production and rift development”? Don’t these seem inconsistent? Sorry to be so critical in this comment:(

    Comment by outeast — 12 Jun 2008 @ 7:29 AM

  3. letter to the editor
    Chapel Hill (NC) Newspaper
    June 11, 2008

    Solutions exist if we apply the science.

    Humankind is surely experiencing the fulfillment of a Chinese proverb: “We live in interesting times.” Many of our brilliant scientists report that God is a delusion. On the other hand, intuitive and gifted believers regularly tell us that these scientists themselves suffer from a form of delusional atheism. No one knows, I suppose, which of these groups is correct.

    I am one of those people who believes the family of humanity can use God’s gift of science to take the measure of any global challenge and find solutions that are consonant with universal values. But, before we can move forward to reasonably address and sensibly overcome a challenge to human wellbeing and environmental health such as global warming, that challenge needs to be openly acknowledged and widely discussed. I suppose it is a function of my life experience to suggest that we accurately “diagnose” whatever the challenge is before proceeding to implement “treatment” options.

    If great spiritual and scientific leaders are somehow on the right track when realizing, “The Earth has a human-induced fever and could overheat,” then at least one available treatment option is to carefully and skillfully examine the extant scientific evidence related to global warming and to make necessary changes in human behavior, both individually and collectively.

    All of the above serves to set the stage for our consideration of a question. How can politicians and economic powerbrokers in the human community be empowered to muster the “political will” necessary for addressing human-driven climate change as well as for providing the substantial economic incentives and financial capital necessary to overcome this potential global threat to life as we know it and the integrity of Earth? — Steven Earl Salmony, Chapel Hill

    Comment by Steve Salmony — 12 Jun 2008 @ 8:02 AM

  4. I am completely uninterested in how the ice breaks up when melting. Much more important is how much heat is being absorbed when this ice changes to water. Any glacial experts out there care to total up this energy absorbed (terawatts/year) and relate it to what the earths’ temp. would be without this cooling provided by melting ice?

    Comment by Michael Lucking — 12 Jun 2008 @ 8:32 AM

  5. Bad new came from the North Pole recently:

    less ice means more rapid warming of permafrost than GCMs are projecting. Anybody surprised?

    Comment by Alexander Ač — 12 Jun 2008 @ 9:25 AM

  6. I am curious about the relationship between Antarctic sea ice and ice shelves. There has been a recent increase in sea ice. What is causing the increase? And will it help stabilize the ice shelves?

    Comment by Peter Houlihan — 12 Jun 2008 @ 10:20 AM

  7. Very informative article!

    I wonder what kind of effect high-latitude ocean warming is having on the ice shelves. One study from a few years ago looked at the causes of the “rapid” growth of Antarctic ice sheets 14 million years ago. The press release is at

    By studying chemical changes in deep sea sediments, scientists at the University of California, Santa Barbara discovered that high-latitude Southern Ocean cooling helped to trigger this major expansion of Antarctic ice sheets, which have since become a permanent feature of the global climate system. These results document ice sheet history and supply crucial insight into the dynamics of the global climate system. . .

    Southern Ocean temperature data exhibits a rapid 7 degree cooling of surface waters around 14 million years ago and suggests a strengthening of the Antarctic Circumpolar Current in response to changes in the geometry of Earth’s orbits. As a result, Antarctica became increasingly isolated from tropical heat and moisture sources. Records of Antarctic ice volume indicate that following this cooling ice sheets expanded rapidly to near present-day size, which suggests that changes in the Southern Ocean directly influence the size of the Antarctic ice sheet.

    As we rapidly increase the ocean temperatures, will we also see a rapid warming of the Southern Oceans? Unfortunately there is not much Southern Ocean temperature data – but predictions are that rising temperatures will have widespread impacts. ( ). Antarctic sea ice extent remains mostly unchanged:

    The thickness of the sea ice is also important. The thinning of the Arctic sea ice cover began at least two decades before the decrease in actual coverage did (as recorded by U.S. submarines). A nice discussion of the Antarctic sea ice thickness is at

    If you want to see some ridiculous coverage of this issue, check out Pielke Sr.’s March 27 2008 post. Their choice of references? ICECAP, the latest version of fossil fuel investor-funder anti-science PR.

    Comment by Ike Solem — 12 Jun 2008 @ 10:53 AM

  8. Last southern hemisphere winter, the sea ice extent was the greatest since the invention of sattelite mounted cameras. This year, this date, the southern hemisphere sea ice extent is 1-million square kilometers ahead of last year (about 6 percent of last years record).
    Is there some global climate model that predicts anything like that occuring?

    [Response: The overall SH trends are not significant notwithstanding some big years recently. Trends in the different sectors are though. There has been a decrease to the west of the Antarctic peninsula, and an increase to the east – conceivably associated with a long term positive trend in the Southern annular mode (SAM). That increase is suggested by models as a response to the Antarctic ozone hole and increasing greenhouse gases. Significant decreases in SH sea ice are not expected yet – but I haven’t examined the ensemble of model runs to see what their variability is like in SH sea ice. – gavin]

    Comment by Gary Plyler — 12 Jun 2008 @ 11:06 AM

  9. Thanx for the column. I was just reading the paper by Wiens et al.,”Simultaenous teleseismic and geodetic observations of the stick-slip motion of an Antarctic ice stream”, Nature, v453, p770, 5 June 2008. I recall that similar icequakes have been recorded in NE Greenland, and I was wondering if there had been similar studies there (or elsewhere). There was another nice recent paper about a set of interconnected subglacial Antarctic lakes filling and draining within days, but i do not remember that any seismic signature was recorded.

    Another question occurred to me: from the Wiens paper, the total ice moved into the Ross ice shelf by a single ice stream seems to be on the order of several 1000 km^3/yr. The estimate from GRAVIS for net ice mass loss from all of WAIS is on the order of several hundred km^3. So the difference must be made up by thickening of the ice shelf and snow accumulation. But it seems that the net ice mass loss is the difference of two much larger numbers: the total snow accumulation less the total melt and calving loss. Each of these seems to be on the order of 1e5 km^3. So the net mass loss is on the order of 1% of total snow accumulation or total mass loss.

    Does this not indicate that even a 1% increase in melting/calving rate will double net mass loss ?

    On a related note: do any ice sheet models predict increase in sea ice as the ice shelves collapse and float away ?


    Comment by sidd — 12 Jun 2008 @ 11:38 AM

  10. RE #4 “Any glacial experts out there care to total up this energy absorbed (terawatts/year) and relate it to what the earths’ temp. would be without this cooling provided by melting ice?”

    I’ve also been looking for an answer to this question. In the GISS land-ocean temperature data ( the first quarter of 2008 was the coolest since 4Q 2000. Is it reasonable to look for a relationship between this cool trough and the recent Wilkins Ice Shelf event?

    There’s an entanglement between this technical issue and the subject of human perceptions: if ice-sheet failure can be expected to postpone effects of climate-change (such as temperature rise), how long will this reprieve last, and how will it affect our response?

    An example of such entanglement can be seen just above, in posts 6 and 7. It can be a mistake to rely on common sense where complex systems are involved, but it seems natural to expect that when ice-sheets break up, the former sheet-ice becomes sea-ice (for a few months, anyhow). Where else would it go?

    Comment by Daniel C. Goodwin — 12 Jun 2008 @ 11:43 AM

  11. Many comments have noted the sea ice extent and its role. The sea ice itself has not too date been identified as a factor in ice shelf breakup, in general the ice sheves see little open water at their front. The potential problem would be increased wave action at the ice shelf front. At this point it would be pure conjecture to consider its impact. That is the point of the upcoming study proposed by Scambos and Massom. At this point it is hard to anticipate an impact on the larger ice shelves such as the Ross Ice Shelf, but on the thinner ice shelves on the Peninsula it could be a final straw that helps accentuate the near ice front rifting. #2 I am sure you are correct, that the article could you use more proof reading, not my strongest suit. The mechanims noted basal melt, surface melt and rifting are not unrelated nor inconsistent. They clearly work in concert, the question is the details behind the relationships. In the case of WIS there seems to be less of a role of surface melt. The rifting does require some thinning mechasism to pre-condition to prime the ice shelf for rifting. #4 The role in the earth’s heat budget of the breakup of the ice shelves, I do not know. It is definetly of much less importance than the potential for ice shelf breakup and consequence for accelerating feeder glaciers to raise sea level. You should care as much about the ice shelves as any aspect of global warming.

    Comment by Mauri Pelto — 12 Jun 2008 @ 11:45 AM

  12. The link to the University of Texas’s (Austin) Secrets of the West Antarctic Ice Sheet is still good. This symposium can be viewed on the web. The British Antarctic Survey does a presentation that discusses the role of increased current velocity on the melting of ice shelf bases. They note that it is increased wind speed, driving ocean currents that are causing the increase in shelf base melt. I guess that the wind increase is a result of the ozone hole versus global warming. But, global warming should more than take up the slack as the hole begins to close in 30 or so years.

    I enjoy your grammar as it reminds me fondly of my father in law’s speech (Peruvian).

    Comment by Andrew — 12 Jun 2008 @ 12:23 PM

  13. “Any glacial experts out there care to total up this energy absorbed (terawatts/year) and relate it to what the earths’ temp. would be without this cooling provided by melting ice?”

    What you should really be asking, given that sea ice coverage has been growing globally, is how much cooler the global temperatures would be without this effect of latent heat being introduced into the environment as H2O moves to a more ordered state ie ice.

    Comment by Alan Millar — 12 Jun 2008 @ 12:39 PM

  14. Nice summary syntax.

    May we conclude that possibly the Arctic could be free of shelves and platforms this summer? I heard the year 2013 predicted. And surely that does not mean floating ice free, but rather just sheets and platforms of a certain size. How will that remaining ice be counted?


    Comment by Richard Pauli — 12 Jun 2008 @ 1:47 PM

  15. Gavin says
    “Significant decreases in SH sea ice are not expected yet – but I haven’t examined the ensemble of model runs to see what their variability is like in SH sea ice. – gavin”

    Are you talking about sea ice extent or sea ice thickness? More interestingly, what might be some of the features that caused climate models to miss the rapid retreat of Arctic sea ice?

    Comment by Ike Solem — 12 Jun 2008 @ 2:17 PM

  16. Gavin said “The overall SH trends are not significant notwithstanding some big years recently. Trends in the different sectors are though”

    Why would total SH sea ice not be significant amongst other trends? Would not sea ice be a measure of global warming which would lead to increased sea levels? If the SH sea ice is growing, one would presume temps are colder or below freezing for a longer period of time, thus reducing melting and increases in sea levels. Also, considering the recent increases in global temps, why wouldn’t record winter 07 SH sea ice, followed by winter 08 SH on record pace, not be noteworthy? Is it because it runs against consensus? Clearly there is some importance behind SH sea ice and last year’s record and this years pace.

    Comment by floodguy — 12 Jun 2008 @ 2:42 PM

  17. #5 Alexander Ač

    Surprised? Sadly Not. :(

    If the Arctic goes rapidly (I think it will), then much of the projection and impacts work of the IPCC becomes irrelevant. Which is not a good thing.

    Mauri Pelto.
    Thank You.

    Comment by CobblyWorlds — 12 Jun 2008 @ 2:45 PM

  18. #17

    Not necessarily. The Arctic has historically experienced more extremes than the rest of the planet. Even if the sea ice reaches another record low, that doesn’t necessarily mean global warming is exceeding the IPCC projections…note that the extremely low Arctic sea ice of last fall still led into one of the colder northern hemisphere winters in recent memory.

    So the weather at the poles does not necessarily indicate global weather trends.

    Comment by Sean Rogers — 12 Jun 2008 @ 3:48 PM

  19. Re: #16 (floodguy)

    I don’t think Gavin meant “significant” in the sense of “important” or “meaningful,” but rather in the sense of “statistically significant,” i.e., distinguishable from random noise.

    However, the change in southern hemisphere sea ice extent is statistically significant — just barely. This is mainly due to the high values so far in the 1st half of 2008; if they persist, the trend will remain significant but if they don’t the trend will probably not remain significant. Using data from late 1987 (the beginning of satellite observations) through May 2008, SH sea ice extent shows a positive trend rate of +12,000 km^2/yr. NH sea ice extent currently shows a negative trend rate of -131,000 km^2/yr.

    [Response: Thanks for the update. Might be worth doing as a proper post… – gavin]

    Comment by tamino — 12 Jun 2008 @ 3:53 PM

  20. [#4] – You can find your answer in the Technical Summary of the AR4 IPCC report:
    (See Figure TS.15)

    The short answer is that heat absorbed by the oceans dominates the energy content of the earth climate system – eg by a factor of 100:1 for global oceans:Arctic sea ice

    Comment by Timothy — 12 Jun 2008 @ 4:32 PM

  21. Why would total SH sea ice not be significant amongst other trends?

    Insert the word STATISTICALLY before the word SIGNIFICANT in Gavin’s comment. He’s assuming that readers know what “significant” means when speaking of trends.

    Clearly there is some importance behind SH sea ice and last year’s record and this years pace.

    Well, no, actually.

    Comment by dhogaza — 12 Jun 2008 @ 4:39 PM

  22. #16 Floodguy,

    Southern Hemisphere Anomaly
    Northern Hemisphere Anomaly

    And to get some idea of the perspective of those wiggles:

    Southern Hemisphere Anomaly
    Northern Hemisphere Area

    Last year’s Arctic drop was 25%, that’s together with a whole range of observations that show a substantial change in the Arctic that outweighs the significance of the Antarctic sea-ice changes. In terms of sea ice they are very diferent issue; nobody is seriously talking about losing the Antarctic Ice Cap within a decade.

    Comment by CobblyWorlds — 12 Jun 2008 @ 4:55 PM

  23. I’m intrigued by Ike’s post (currently #7). An increase in the westerlies that circle the globe around Antarctica is a pretty robust projection in most models (IIRC), and has already been observed, at least to some extent. Those westerlies help to drive the circumpolar current, so as they intensify, we should see the current become stronger. The wind belts are also projected to move towards higher latitudes.

    The paper that Ike quotes from suggests that this may have been the mechanism for rapid glaciation 14 million years ago. If that is true, then there is the possibility that as warming progresses there might be further Antarctic cooling (irrespective of ozone recovery). I suppose there’s also the possibility that increased storminess around the fringes of Antarctica could provide a mechanism to get moisture into the interior, and thus grow more ice.

    If the Arctic goes rapidly (I think it will), then we may see a world with only one cold pole. and I doubt that’s been modelled anywhere…

    Comment by The Tuatara — 12 Jun 2008 @ 5:07 PM

  24. Floodguy, what Gavin probably means is that the recent SH sea ice extent variations are not statistically significant, unlike Arctic sea ice.
    See this:

    Remember that sea ice is frozen sea water floating on the ocean, hence its melting does not affect sea level like accelerated flow/melt of ice sheets.

    Comment by Philippe Chantreau — 12 Jun 2008 @ 5:54 PM

  25. I think the point here is that sea ice volume is a the critical measure, which is a function of both thickness and extent.

    In the Arctic, sea ice thinning preceded the loss of summer sea ice by decades. In the Antarctic, due to a lack of historical data (it seems unlikely that U.S. submarines would have collected datasets on Antarctic sea ice thinning – but maybe?), we don’t know what the sea ice thickness trend is.

    If you want to look at the actual data for the past decades on sea ice extent, see

    The pattern so far is that thinning sea ice results in an ice pack that is far more sensitive to wind and current forcing than a thicker ice pack. Yet we simply have no idea of what the thickness trend in Antartic sea ice is. Using sea ice extent to predict future trends is nonsensical – If you had looked at Arctic sea ice extent up to 2005, you would have not predicted the sudden summertime collapse, right?

    The real topic here, however, is how fast mass will be lost from the West Antarctice Ice Sheet. If we get accelerated ice loss from Greenland and the WAIS, that would mean that IPCC predictions of 21st century sea level rise are underestimates.

    Comment by Ike Solem — 12 Jun 2008 @ 6:52 PM

  26. Let’s remember that all icebergs come from the calving of ice shelves or the calving of glaciers at the coast.

    If someone could show the number of icebergs has increased recently, then one could show the break-up of ice-shelves is unusual in an historical context.

    Comment by Lowell — 12 Jun 2008 @ 7:29 PM

  27. Floodguy, you seem to be having trouble parsing the sentence. OK first find the subject: SH trends. This means that the way things are changing, and since this is “realclimate” and not “realweather”, a trend is of order decades. Now let’s find the verb–there it is: are. And it is negated by the “not” and then we have the predicate: significant. So basically, what tat means is that you have a couple of years, and that’s weather. Hence THE TREND is not significant. That help?

    Comment by Ray Ladbury — 12 Jun 2008 @ 7:47 PM

  28. You can do the math on the effect of latent heat. It takes 333.55 kJ/kg to melt water, so 1 cubic km of water takes about 3 x 10^17 joules to melt. Given the difference in albedo between ice and water, this will be made up in about 5 years due to increased solar absorption once the ice is gone.

    Comment by Ray Ladbury — 12 Jun 2008 @ 8:06 PM

  29. “station temperature records for the past 50 years and report statistically insignificant temperature fluctuations over continental Antarctica excluding the Antarctic Peninsula, with the exception of Amundsen-Scott South Pole Station, which cooled by -0.17 K decade-1 for 1958–2000”
    Monaghan, A. J., D. H. Bromwich, W. Chapman, and J. C. Comiso (2008), Recent variability and trends of Antarctic near-surface temperature, Journal of Geophysical Research, 113, D04105, doi:10.1029/2007JD009094.

    Mackintosh, A., White, D., Fink, D., Gore, D.B., Pickard, J. and Fanning, P.C. 2007. Exposure ages from mountain dipsticks in Mac. Robertson Land, East Antarctica, indicate little change in ice-sheet thickness since the Last Glacial Maximum. Geology 35: 551-554.

    The mass of Antarctica’s grounded ice sheet has been steadily growing over the past quarter-century.
    Van de Berg, W.J., van den Broeke, M.R., Reijmer, C.H. and van Meijgaard, E. 2006. Reassessment of the Antarctic surface mass balance using calibrated output of a regional atmospheric climate model. Journal of Geophysical Research 111: 10.1029/2005JD006495.

    “The advent of satellite imagery since the mid-1970s enabled scientists to remotely ‘view’ Antarctica and measure the extent of sea ice. This data shows little or no change, or possibly even an increase in sea ice extent since the 1970s. So what is happening? Is Antarctic sea ice extent increasing or decreasing? The answer is both! The effect seen depends on the timescale we are considering.”

    44.1% greater ice extent and 30% greater ice concentration in January 2008 compared to 1980.

    Comment by Richard Wakefield — 12 Jun 2008 @ 8:32 PM


    Comment by Spyros — 12 Jun 2008 @ 9:00 PM

  31. If there are significant calving events over several years then surely we must expect the extent of sea ice to increase by a sort of ice-cube in your drink effect. The surrounding ocean will lose heat to the melting of the shelves and so be more prone to seasonal freezing.

    Comment by jeff bryant — 12 Jun 2008 @ 9:01 PM

  32. Could the meltwater/crevasse phenomenon affect glaciers as well? If so, and meltwater eats through the bottom of glacial crevasses to reach ground level, could this lead to the feared effect of glaciers becoming much more lubricated and moving into the sea significantly faster?

    Comment by James Haughton — 12 Jun 2008 @ 9:19 PM

  33. Here’s the link to the Secrets of the West Antarctic Ice Sheet panel discussion. I’d forget my head if it weren’t attached. The British Antarctic Survey presentation discusses the hypothesis that increased wind speed and thus increased currents are raising air and water temperatures on and under the ice shelves.

    Comment by Andrew — 12 Jun 2008 @ 10:27 PM

  34. Gavin – Floodguy’s questions about SH ice would sure seem relevant to global conditions. Are you suggesting that the SH anomaly is statistically insignificant or climatologically insignificant or both?

    Comment by Joseph Hunkins — 13 Jun 2008 @ 2:27 AM

  35. Hi climate people,

    Is “Cryosphere today” a good source of scientific information ?
    The time of year right now is at the precipice of last years massive anomaly :

    Do people think this was just a bad year or will there be an even deeper anomaly this year as all that single year ice is rapidly melted, before multiyear ice manages to slow the melt.

    Looking at the anomaly in 2006, it looks like the anomaly in 2007 starts from where the 2006 anomaly left off.
    If that is what happens I think we can expect to quickly get back to -3 million square km and then reach a minimum of around -4 million square km (or a remaining ice area of 2 million km) this year.
    Is there any more thorough analysis of this data to predict the coming year or do we have to wait till the data becomes statistically significant by which time there will likely be 0 square kilometers of ice summer.


    Comment by Alex Burton — 13 Jun 2008 @ 5:22 AM

  36. [29] – Looking at the anomaly graphs posted in [22] by CobblyWorlds, it is clear that 1980 was a fluke negative outlier. Using it as a comparison for the 2008 positive spike is misleading.

    You should compare to a longer period mean. When you do so the difference between the two poles is clearly apparent. There is a very consistent negative trend in NH sea ice, which is accelerating. SH sea ice is mostly stable, with much greater noise and some recent positive spikes.

    The difference in no way undermines the Arctic signal as an important sign of global warming happening now.

    Comment by Timothy — 13 Jun 2008 @ 5:22 AM

  37. It is an odd phenomenon a discussion starts on ice shelves, and yet sea ice becomes the topic, hmmmmm. There seems to be several point of confusion. First a numberof posts indicate that the impact on the energy balance of the region would be impacted by the WIS breakup. Well no, compare the volume of ice involved to the the volume of ice that comprises the sea ice or even the ice on a large lake like Lake Erie in the winter, and you will be reminded that ice melt has a limited role in cooling already cold water or in cooling the air overhead. Second the amount of icebergs by areal extent compared to the Antarctic sea ice is tiny and is not an important contribution to the formation of further sea ice or to the overall heat balance of the system. The sea ice in the southern hemisphere also lacks the potential impact of the ice sheet. The role of meltwater in crevasse formation and exploitation is minor on most glaciers, however, on thin sections of ice shelves, the post notes that it does have a role, a thermal role. It is a role that was observed on the Larsen, but not on the WIS. The purpose of the post it to illustrate that it is beginning to appear that meltwater was not the key to the breakup of these ice shelves, but did have a significant pre conditioning role. The main pre-conditioner is rifting which is more robust when the ice shelf becomes thinner.

    Comment by Mauri Pelto — 13 Jun 2008 @ 6:14 AM

  38. Dear All,

    Tamino has posted a rather sobering (as if we needed more — where is my merlot?) description of new research showing that the permafrost in the north is on its way to meltdown with attendant consequences.

    Comment by Tenney Naumer — 13 Jun 2008 @ 7:26 AM

  39. Joeduck–A couple of years worth of data is “weather” not climate. You just can’t hope to wrest signal from noise for such a short period of time. Remember, what we’re talking about here is “GLOBAL CLIMATE CHANGE”. It is important to understand what all three of those words imply.

    Comment by Ray Ladbury — 13 Jun 2008 @ 7:45 AM

  40. #11 Mauri Pelto (whom I thank for the article and apologise to for my ignorant comment) wrote:

    “The role in the earth’s heat budget of the breakup of the ice shelves, I do not know.”

    Am I guilty of another “insignificant” misreading wrt your “heat budget”? Surely the breakup of the ice shelves is due to anthropogenic global warming?

    Comment by Alan K — 13 Jun 2008 @ 7:58 AM

  41. RE # 18

    Sean, you said:

    [So the weather at the poles does not necessarily indicate global weather trends.]

    On what reserach, published studies, you base that comment.

    Fact is, we do not know the impact of a massive dark surface at the Arctic Ocean on the convective currents, percip and temp of western NA. The world population and Archer Daniel Midland depend upon climate stability in Western NA; some for survival and others for profit (i.e., ethanol).

    If you have insights we do not yet have, please share them.

    John McCormick

    Comment by John L. McCormick — 13 Jun 2008 @ 8:04 AM

  42. The reasons for the ice sheet breaking of is due to tectonic activity along the Antarctic Peninsula. Undersea volcanic activity is warming that part of the oceans.

    Notice in this NASA image of the warmer oceans along that region:

    That’s where the volcanic activity is happening along the plate boundary.

    “Scientists Discover Undersea Volcano Off Antarctica
    ScienceDaily (May 31, 2004) — ARLINGTON, Va. — Scientists working in the stormy and inhospitable waters off the Antarctic Peninsula have found what they believe is an active and previously unknown volcano on the sea bottom.”

    The melting ice sheet there has nothing to do with global warming. I ask the question again, how many things that do not support AGW must happen before you at RC give up AGW? What is needed to falsify the theory?

    [Response: The question should be what will it take to stop people grasping at the flimsiest straws before they accept that climate is changing? There is no volcano under the Wilkins ice sheet – nor the Larsen B (actual location). Blaming that for the warming seen thousands of miles away on the other side of the Peninsula is like blaming Mt Etna for the European 2003 heat wave. – gavin]

    Comment by Richard Wakefield — 13 Jun 2008 @ 8:45 AM

  43. #19 thank you Tamino and others for the replies.

    On a different note, do you foresee any affect to NH ice from a negative PDO, if the PDO has indeed turned negative?

    Comment by floodguy — 13 Jun 2008 @ 9:46 AM

  44. Joeduck, see Gavin’s inline response to #19, and Tamino’s postings.
    “Barely significant statistically” — and it’s the two-dimensional area is what’s watched there.

    Reports of melting from underneath are discussed above.

    Get a lot of fresh water released from melting underneath, it rises above the denser salt water — and perhaps some of that freezes again around the edges during the winter as the air’s cold? I’d speculate that’s happening. People on the spot will find out.

    Comment by Hank Roberts — 13 Jun 2008 @ 10:07 AM

  45. About Arctic summer 2007 sea ice please see

    Zhang, Jinlun, Ron Lindsay, Mike Steele, and Axel Schweiger, 2008. What drove the dramatic retreat of arctic sea ice during summer 2007? Geophys. Res. Lett., 35, L11505, doi:10.1029/2008GL034005, June 11, 2008


    A model study has been conducted of the unprecedented retreat of arctic sea ice in the summer of 2007. It is found that preconditioning, anomalous winds, and ice-albedo feedback are mainly responsible for the retreat. Arctic sea ice in 2007 was preconditioned to radical changes after years of shrinking and thinning in a warm climate. During summer 2007 atmospheric changes strengthened the transpolar drift of sea ice, causing more ice to move out of the Pacific sector and the central Arctic Ocean where the reduction in ice thickness due to ice advection is up to 1.5 m more than usual. Some of the ice exited Fram Strait and some piled up in part of the Canada Basin and along the coast of northern Greenland, leaving behind an unusually large area of thin ice and open water. Thin ice and open water allow more surface solar heating because of a much reduced surface albedo, leading to amplified ice melting. The Arctic Ocean lost additional 10% of its total ice mass in which 70% is due directly to the amplified melting and 30% to the unusual ice advection, causing the unprecedented ice retreat. Arctic sea ice has entered a state of being particularly vulnerable to anomalous atmospheric forcing.

    About Arctic Ocean please see

    Liu, Jiping, Z. Zhang, Y. Hu, L. Chen, Y. Dai, and X. Ren, 2008. Assessment of surface air temperature over the Arctic Ocean in reanalysis and IPCC AR4 model simulations with IABP/POLES observations. J. Geophys. Res. – Atmos., 113, D10105, doi:10.1029/2007JD009380, May 21, 2008


    The surface air temperature (SAT) over the Arctic Ocean in reanalyses and global climate model simulations was assessed using the International Arctic Buoy Programme/Polar Exchange at the Sea Surface (IABP/POLES) observations for the period 1979–1999. The reanalyses, including the National Centers for Environmental Prediction Reanalysis II (NCEP2) and European Centre for Medium-Range Weather Forecast 40-year Reanalysis (ERA40), show encouraging agreement with the IABP/POLES observations, although some spatiotemporal discrepancies are noteworthy. The reanalyses have warm annual mean biases and underestimate the observed interannual SAT variability in summer. Additionally, NCEP2 shows an excessive warming trend. Most model simulations (coordinated by the International Panel on Climate Change for its Fourth Assessment Report) reproduce the annual mean, seasonal cycle, and trend of the observed SAT reasonably well, particularly the multi-model ensemble mean. However, large discrepancies are found. Some models have the annual mean SAT biases far exceeding the standard deviation of the observed interannul SAT variability and the across-model standard deviation. Spatially, the largest inter-model variance of the annual mean SAT is found over the North Pole, Greenland Sea, Barents Sea and Baffin Bay. Seasonally, a large spread of the simulated SAT among the models is found in winter. The models show interannual variability and decadal trend of various amplitudes, and can not capture the observed dominant SAT mode variability and cooling trend in winter. Further discussions of the possible attributions to the identified SAT errors for some models suggest that the model’s performance in the sea ice simulation is an important factor.

    Comment by Timo Hämeranta — 13 Jun 2008 @ 10:52 AM

  46. Richard Wakefield, Want to falsify the hypothesis that humans are behind the current warming epoch? All you have to do is come up with a physical, dynamical model that does as good a job or better of explaining all the trends and doesn’t include an increased greenhouse effect. Of course, then you have to explain why the greenhouse effect should magically stop when CO2 concentration goes above 280 ppmv, but one thing at a time. Go ahead. We’ll wait.

    Comment by Ray Ladbury — 13 Jun 2008 @ 12:27 PM

  47. Volcanoes, Richard? Do they also explain the meltdown of the entire Arctic?

    Comment by Jim Galasyn — 13 Jun 2008 @ 1:56 PM

  48. Image at the top of the thread was:


    “… Wilkins Ice Shelf has experienced further break-up with an area of about 160 km² breaking off from 30 May to 31 May 2008. ESA’s Envisat satellite captured the event – the first ever-documented episode to occur in winter…. animation, comprised of images acquired by Envisat’s Advanced Synthetic Aperture Radar (ASAR) between 30 May and 9 June, highlights the rapidly dwindling strip of ice that is protecting thousands of kilometres of the ice shelf from further break-up.”

    Comment by Hank Roberts — 13 Jun 2008 @ 3:19 PM

  49. Here’s a working link to the animation from ESA, starting with 5/30 and day by day showing the breakup as far as it’s gone. The press release says further cracks in the shelf indicate the breakup is continuing.

    Comment by Hank Roberts — 13 Jun 2008 @ 3:28 PM

  50. Mauri, Thanks for a great summary.

    A couple of points. Although ice shelf thinning does indeed appear to precede ice most ice shelf break-ups, no model has been forwarded yet that connects this thinning to the rapid disintegration process we see in the Larsen A, Larsen B, and Wilkins (and several icebergs in late stages of decay; Scambos et al., 2005 GRL). One possible link, however, is that reduced ice thickness leads to reduced connection with pinning points on the flanks of the shelf, and therefore lower internal compressive stress (or lower net tensional stress, to be accurate).

    Braun, Humbert, and Moll have done an excellent job characterizing the history of change in the Wilkins Shelf, and have detailed how changes in its perimeter (small break-up events) had a near-immediate effect on internal rifting. However, they make one point that I think will be widely mis-interpreted (and I think they are mis-interpreting it themselves): that surface melt ponding had nothing to do with the recent Wilkins break-up event of March, 2008. That is, sensu stricto, true: the only observed surface ponds in the Wilkins are on the northeastern corner of the shelf, well away from the break-up area. But the Wilkins is known to have an intense melt season, and has been observed to have water-saturated firn. This water-saturated condition may be sufficient to drive the hydro-fracture model we describe (Scambos, Hulbe, Fahnestock, 2003; and, of course, it’s based on early related ideas by Weertman and Robin).

    Note that all the ‘disintegration’ events occur in late summer, at the end of large melt seasons. The Larsen A broke up in late January, 1995; the Larsen B in March, 2007, and the Wilkins in March 2008. This seasonality continues to point to surface melting as the key cause of ice shelf break-up.

    Comment by Ted Scambos — 13 Jun 2008 @ 3:42 PM

  51. Mauri,

    Thank you for the excellent article. It’s contributions like this that make Real Climate one of the most valuable websites discussing climate change.

    Are there any ongoing monitoring efforts for the large ice sheets (Ross and Ronne)? If so, have they seen any of the early signs like thinning of the bottom of the ice shelf, formation of rifts or meltwater ponds?

    Comment by Ken Feldman — 13 Jun 2008 @ 4:19 PM

  52. The Wilkins continues to break up.

    Wilkins Ice Shelf has experienced further break-up with an area of about 160 sq. km breaking off from 30 May to 31 May 2008. ESA’s Envisat satellite captured the event – the first ever-documented episode to occur in winter.

    Comment by The Tuatara — 13 Jun 2008 @ 4:31 PM

  53. P.S. from

    WASHINGTON, March 26, 2008 (From AFP) – “Antarctica’s massive Wilkins Ice Shelf has begun disintegrating under the effects of global warming, satellite images by the University of Colorado’s National Snow and Ice Data Center showed. … With the Antarctic summer drawing to a close, scientists do not expect the ice shelf to further disintegrate in the next several months….”

    Good thing they kept watching anyhow. Mauri, what are the researchers saying to each other this weekend?

    Comment by Hank Roberts — 13 Jun 2008 @ 4:43 PM

  54. By the way, this isn’t just an Arctic vs. Antarctic issue…it’s Northen Hemisphere vs. Southern Hemisphere. Take a look at this:

    The northern hemisphere as a whole has been warming faster than the southern hemisphere, both land and water. I realize the common explanation for this is that it’s due to the southern hemisphere being a greater percentage water, but that doesn’t explain why the northern Atlantic has warmed so much more than the southern Atlantic, for example.

    It seems to be an odd phenomenon.

    Comment by Sean Rogers — 13 Jun 2008 @ 4:51 PM

  55. Could you remind us how ice shelf instability is expected to affect sea level rise? If I understand it correctly, the collapse of the ice shelf and subsequent melting of the ice therein doesn’t directly affect sea level, but its secondary effects on the land based glaciers, to which the shelf is attached, do.

    Comment by Leonard Evens — 13 Jun 2008 @ 5:30 PM

  56. Steve Salmony — nice editorial letter. Thank you for posting.

    Comment by Barton Paul Levenson — 13 Jun 2008 @ 6:33 PM

  57. nice animation from esa at

    Comment by sidd — 13 Jun 2008 @ 8:22 PM

  58. Re: #46- ” Want to falsify the hypothesis that humans are behind the current warming epoch? All you have to do is come up with a physical, dynamical model that does as good a job or better of explaining all the trends and doesn’t include an increased greenhouse effect. Of course, then you have to explain why the greenhouse effect should magically stop when CO2 concentration goes above 280 ppmv, ….”

    He might have to do better than that, Ray, as Raypierre says in a post last December ” If somebody comes along and has the bright idea that, say, global warming is caused by phlogiston raining down from the Moon, that does not make everything we know about thermodynamics, infrared absorption, energy balance, and temperature suddenly go away. Rather, it is the job of the phlogiston advocate to quantify the effects of phlogiston on energy balance, and incorporate them in a consistent way beside the existing climate forcings. Virtually all of the attempts to poke holes in the anthropogenic greenhouse theory lose sight of this simple and unassailable principle.”

    It’s going to take another Copernicus to make that drastic a change in our worldview.

    Comment by Lawrence Brown — 13 Jun 2008 @ 9:16 PM

  59. If i may repeat some of a post from 9 July 2007:

    Mercer, Nature, 1978, v271 pp.321-325
    “One warning sign that a dangerous warming is beginning in Antarctica, will be a breakup of ice shelves in the Antarctic Peninsula just south of the recent January 0C isotherm; the ice shelf in the Prince Gustav Channel on the east side of the peninsula, and the Wordie Ice Shelf; the ice shelf in George VI Sound, and the ice shelf in Wilkins Sound on the west side.”
    Smith et al. Antarctic Science, 19(1), pp131-142 (2007)


    Comment by sidd — 13 Jun 2008 @ 10:14 PM

  60. I didn’t go through all the comments so this might have been posted, but another recent study at least suggests that increased shortwave flux because of less cloud cover did not contribute substantially to the anomalous NH sea ice decline in September 2007

    A. J. Schweiger et al., Did unusually sunny skies help drive the record sea ice minimum of 2007?, GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L10503, doi:10.1029/2008GL033463, 2008

    I do have a question for anyone here who may have played with GIS data on this, particularly from here ( and linked inside ). Monthly sea extent shapefiles are here, and I put them into ArcGIS and used the tool to sum up the extent of the polygons and from GIS, September 2007 extent appears to be far less than 4 x 10^6 sq. kilometers (it was in the mid to high 3’s), as opposed to the literature value of ~4.28 x 10^6 sq. kilometers. Sea ice extent far less than the literature value seems consistent, so I was wondering if anyone had any insight into the shapefiles here?

    Comment by Chris Colose — 13 Jun 2008 @ 10:26 PM

  61. # 44: Comment by Hank Roberts, 13 June 2008 10:07 AM
    “Get a lot of fresh water released from melting underneath, it rises above the denser salt water — and perhaps some of that freezes again around the edges during the winter as the air’s cold? I’d speculate that’s happening. People on the spot will find out.”

    If this is correct, we ought to see a salinity signature toward the ocean surface. I am playing with the data at

    but more qualified opinions are probably available here


    Comment by sidd — 14 Jun 2008 @ 12:27 AM

  62. Re 46: There is far too much reliance on models. The real world has a habit of not wanting to play by your rules. What is going to falsify AGW is the planet itself. It’s just going to take a few more years, as in a previous post that RC staff have admitted it would take of continued no increase in temp for the next 10 years.

    The fact remains that there are serious problems with AGW predictions; the most serious of all is that sea level rise has not accelerated from the 1.7mm/yr it has been for the past 110 years of measurements (If AGW were true, depending on who’s making the prediction, sea level rates would have to rise from 3 to 40 TIMES the current rate, IPCC and Gore respectively).

    If all these glaciers and ice is melting, why has this not shown up in the rate of sea level rise? If the excuse is that it will take a few more years before the change happens, then the current rate of rise is NOT due to global warming as the media claims. They are wrong to make the claim that current sea level rise is due to global warming. If there is a lag then that claim MUST be false.

    Models must be tested against reality, and so far your models of sea level rise have failed completely. How many more years of no acceleration are required before AGW is rejected?

    Comment by Richard Wakefield — 14 Jun 2008 @ 8:51 AM

  63. Here is a decent news article on the ice shelves:

    Glaciologists are concerned about Antarctica’s ice shelves because most of them represent brakes of solid ice that slow the glaciers’ flow to the sea. Without those brakes, the glaciers would surge, calve into icebergs, and significantly raise the sea level.

    The region of greatest concern is West Antarctica, which includes the peninsula. Using satellites, scientists have been tracking snowfall, ice loss, and changes in the region’s gravity field to gauge the amount of mass the continent’s two large ice sheets are gaining or losing. The West Antarctic Ice Sheet is separated from its eastern sibling by a long chain of mountains, so gains or no change in mass for the continent as a whole may still mask significant changes on the West Antarctic Ice Sheet.

    What is really odd is that even though the evidence is in (both poles are melting, as are mountain glaciers, endless numbers of American reporters and editors still feel compelled to place the statement “Some skeptics believe global warming is a hoax” at the bottom of every single news article they write on climate and weather. I actually called one of them up, and politely asked who they were quoting – “official NWS and NASA spokespeople” is the response I got. I then asked if they had read the news stories about political suppression of scientists at NASA, NOAA and the NWS – and then I asked why they didn’t feel compelled to place “Some skeptics believe AIDS is a hoax” on stories about that epidemic? The reporter got very upset and asked why I was “harrassing her.” I replied that she was the one who wrote the story, wasn’t she?

    Comment by Ike Solem — 14 Jun 2008 @ 8:58 AM

  64. The continuing WIS disintegration is expected, just not yet, so glaciologists thought we could relax through the Austral winter, but does not appear so. The rifts seen on May 30 near the front for the WIS make it clear that not much was holding it together. Compare to the rifts in March in the original post. This is a dynamic process that we are beginning to understand and it is fascinating and frightening to observe. Until recently most of the glaciologic research has focussed on the larger ice streams of West Antarctic feeding the Ross and Ronne-Filchner ice Shelves. In the case of the Ronne-Filchner ice shelf, there has been a bit of a thickening of the ice streams near the transition to the floating ice shelf. This and the relatively consistent velocity of the ice streams feeding this complex indicates the comparative stability of this system.

    A view of changes in the front of the Ross ice Shlef prepared by the USGS is seen at
    This view shows little coherent change, instead it is the occassional massive iceberg breakoffs that control the ice front changes.
    #55 You are exactly right. Just picture, you are in a kayak with the nose of your boat pressed against a large flat floating piece of ice in your way, you can move it but it slows you down. Now a change in the current moves the ice out of your way and all of a sudden forward progess is easier. Same thing for a glacier that feeds an ice shelf.

    Comment by Mauri Pelto — 14 Jun 2008 @ 9:50 AM

  65. RE: #42


    I’ve looked at your links and although there have been some fairly recent discoveries of geologic activity and structures in the Antarctic little or none of it seems to be new in the geologic sense. In fact, one article suggests that some of the geologic structures are being observed for the first time because of recent ice retreat/melt. No argument is made in the article that geologic activity is the cause of the recent melting.

    If this activity isn’t new and ice sheets and glaciers are now melting, how could these ice structures have been formed in the first place? Given this and Gavin’s point regarding the proximity of the volcanoes to the areas where most of the melting/breakup is being observed your argument doesn’t have a lot of merit.


    Comment by Peter Backes — 14 Jun 2008 @ 10:11 AM

  66. Just my 2c… On today’s page,, ESA’s title is “Even the Antarctic winter cannot protect Wilkins Ice Shelf”. Well, yes, it’s full winter down there… Wilkins further disintegration was supposed to continue in next january or february, not in June. It’s just like seeing Greenland thawing in December…

    For Alex #35 and others, many scientists monitor Artic this summer. Their outlooks are summarized here: May’s Outlook has been issued recently – but sure to read the “Full report” tab. And, this will continue all summer long.

    Comment by FredT34 — 14 Jun 2008 @ 4:32 PM

  67. Richard (62), you’re simply wrong. Sea level rise was 3.1 +/- 0.7 mm per year from 1993 to 2003. It was 1.7 mm per year from 1.7 (+/- 0.5) mm per year over the 20th century, and slightly more from 1961 to 2003.

    Comment by Chris Colose — 14 Jun 2008 @ 5:20 PM

  68. Richard Wakefield (62) — Regarding observed and predicted sea level rise, see the section of the Technical Summary from

    Should help you to discover these have little to do with ‘models’.

    Comment by David B. Benson — 14 Jun 2008 @ 5:34 PM

  69. sorry for the typing error in #67

    I’d also add that sea level rise is not unique to “A”GW. I wonder why Richard signled out CO2, as opposed to the sun or cosmic rays?

    Comment by Chris Colose — 14 Jun 2008 @ 5:53 PM

  70. Richard Wakefield says: “There is far too much reliance on models.”
    Would you prefer Ouija boards? Psychics? Tea leaves? Sorry, Richard, that is what scientists do–take measurements and come up with models that explain them.
    In the time you have been posting demonstrated denialist drivel, you could have made a start at learning the actual science of climate. No one says you have to believe it, but at the very least it would come closer to informed skepticism, rather than ignorant rants. So, let’s start with lesson 1–the oceans are really, really big. Climate changes on scales of decades. Also remember that as sea level continues to rise, it takes more water to make up the same rise.
    In any case, I’d say it’s probably too early to say whether sea level rise rate is not increasing. Do you have hard data otherwise or is this another of your volcano stories?

    Comment by Ray Ladbury — 14 Jun 2008 @ 6:23 PM

  71. “How many more years of no acceleration are required before AGW is rejected?”

    Keep repeating your mantra, Richard, it keeps you busy and out of the way.

    Comment by Jim Eager — 14 Jun 2008 @ 7:33 PM

  72. Re: 62 Richard states, “that sea level rise has not accelerated from the 1.7mm/yr it has been for the past 110 years of measurements”

    Sea level rise from 1993 to the present has been 3.3 mm/year, about double the past century’s rate of rise. See this link:

    Comment by Ken Feldman — 14 Jun 2008 @ 10:09 PM

  73. I do not see any discussion of the history of the ice shelf being discussed. According to an article in CS Monitor (, the Wilkins ice shelf is relatively modern, having only formed in the past thousand years or two, and may have formed with the onset of the “Little Ice Age.” If true, then leaving this sort of information out of the discussion may make the current break up of the shelf seem a little more serious than it actually is. If the Wilkins ice shelf is transient, then why shouldn’t it break up … what’s the big deal?

    Comment by Rob Huber — 14 Jun 2008 @ 11:43 PM

  74. Re # 62 Richard, about sea level rise you are correctly informed about the latest study which is:

    Berge-Nguyen, M., A. Cazenave, A. Lombard, W. Llovel, J. Viarre, and J.F. Cretaux. 2008. Reconstruction of past decades sea level using thermosteric sea level, tide gauge, satellite altimetry and ocean reanalysis data. Global and Planetary Change Vol. 62, No 1-2, pp. 1–13, May 2008

    The IPCC and debaters here are outdated. We see a rise in sea level that is below the estimate of the IPCC and we see no acceleration through the past five decades. Basically, nothing seems to be happening with sea level that is remotely out of the ordinary.

    [Response: People ought to read this article and not just take Timo’s summary of it at face value. –raypierre]

    Comment by Timo Hämeranta — 15 Jun 2008 @ 2:45 AM

  75. Comment by The Tuatara — 12 June 2008 @ 5:07 PM

    quote if the Arctic goes rapidly (I think it will), then we may see a world with only one cold pole. and I doubt that’s been modelled anywhere… unquote

    Not modelled, perhaps, but thought about.


    [Response: Actually, people working on initiation of Antarctic glaciation work on this regime all the time. There aren’t many of us, but it happens. Rob DeConto has some of the most complete work published in this area, but I’m doing modelling of this climate state myself for various reasons. There’s a lot to learn, and it is true that doubling or quadrupling CO2 puts the climate on track to look something like the Miocene. I guess Hansen would say we’re at risk of going all the way back too the Eocene but evaluating how realistic that is is one of the things that has gotten a lot of us interested in the time when Antarctic glaciation was just setting in. –raypierre]

    Comment by Julian Flood — 15 Jun 2008 @ 4:36 AM

  76. Richard Wakefield writes:

    The fact remains that there are serious problems with AGW predictions; the most serious of all is that sea level rise has not accelerated from the 1.7mm/yr it has been for the past 110 years of measurements (If AGW were true, depending on who’s making the prediction, sea level rates would have to rise from 3 to 40 TIMES the current rate, IPCC and Gore respectively).

    Wherever you’re getting your information from is wrong. Sea level rise is now up to 3.3 mm/yr.

    Comment by Barton Paul Levenson — 15 Jun 2008 @ 5:59 AM

  77. R.Wakefield makes the point we rely on models too much. The beauty of the papers cited here are that they are completely based on observations not models, repeat not models. #73 Rob it is not clear when the ice shelf formed. After more of it is lost a look at the sediments beneath it will identify that. If it is young the importance for global warming maybe reduced. However, I never mention global warming, I see the importance as observing the mechanisms of ice shelf collapse which we must understand.

    Comment by Mauri Pelto — 15 Jun 2008 @ 6:34 AM

  78. Re #4, #10:

    Assuming roughly 10’000 km^3 arctic sea ice loss during the past 20 years, about 15’000 metric tons are melting per second (averaged over the whole year), consuming 4.9 TW (equivalent to a radiative forcing of 10 mW/m^2) or about 1/3 of the world’s primary energy consumption. So it doesn’t even compensate for the heat emitted directly into the atmosphere by human activity. (The data from comment #20 translates to 2.2 TW for the 1993-2003 mean.)

    The lost pieces of Wilkins Ice Shelf (including the recent break-up) have a volume of 120 km^3, assuming they were about 200 m thick. That would be 1/4 of the arctic sea ice loss during 1 year.

    Comment by Clarence — 15 Jun 2008 @ 8:55 AM

  79. Actually, sea level has fallen over the past two years.

    Data uncorrected for changes in average pressure.

    Data corrected with an inverted barometre.

    Comment by Lowell — 15 Jun 2008 @ 9:10 AM

  80. Is there a quantifiable lag time / memory factor involved in ice sheet melt? Global temperatures have not changed for almost a decade so it would seem odd that major changes in ice mass would be underway now unless it were an accumulated response to the previous warmer decades. So doesn’t the present decade presage a leveling off or decrease in melt?

    Also, don’t AGW modes predict that the response at the poles follow rather than precede significant warming at the warmer latitudes? Given that net warming for the half-century is still in the range of half a degree and not accelerating, why would anyone expect any significant AGW response at the poles?

    Comment by George Tobin — 15 Jun 2008 @ 9:26 AM

  81. Re 67: What is your references to back of that claim?

    Abstract: Mean-sea-level data from coastal tide gauges in the north Indian Ocean wereare used to show that low-frequency variability is consistent among the stations in the basin. Statistically significant trends obtained from records longer than 40 years yielded sea-level-rise estimates between 1.06–1.75 mm/ yrear-1 , with a regional average of 1.29 mm yr-1, when corrected for global isostatic adjustment (GIA) using model data, with a regional average of 1.29 mm-1.. These estimates are consistent with the 1–2 mm /year-1 global sea-level-rise estimates reported by the Intergovernmental Panel on Climate Change (Church et al., 2001). ”

    Wunsch, C., Ponte, R.M. and Heimbach, P. 2007. Decadal trends in sea level patterns: 1993-2004. Journal of Climate 20: 5889-5911.
    “a global mean of about 1.6 mm/year, or about 60% of the pure altimetric estimate, of which about 70% is from the addition of freshwater.”


    Nine long and nearly continuous sea level records were chosen from around the world to explore rates of change in sea level for 1904–2003. These records were found to capture the variability found in a larger number of stations over the last half century studied previously. Extending the sea level record back over the entire century suggests that the high variability in the rates of sea level change observed over the past 20 years were not particularly unusual. The rate of sea level change was found to be larger in the early part of last century (2.03 ± 0.35 mm/yr 1904–1953), in comparison with the latter part (1.45 ± 0.34 mm/yr 1954–2003). The highest decadal rate of rise occurred in the decade centred on 1980 (5.31 mm/yr) with the lowest rate of rise occurring in the decade centred on 1964 (−1.49 mm/yr). Over the entire century the mean rate of change was 1.74 ± 0.16 mm/yr. ”
    In this paper we compare sea level trends observed at a few selected tide gauges of good quality records with thermosteric (i.e., due to ocean temperature change) sea level trends over 1950–1998 using different gridded ocean temperature data sets from Levitus et al. (2000) [Levitus, S., Stephens, C., Antonov, J.I., Boyer, T.P., 2000. Yearly and Year-Season Upper Ocean Temperature Anomaly Fields, 1948–1998. U.S. Gov. Printing Office, Washington, D.C. pp. 23.], Ishii et al. (2003) [Ishii, M., Kimoto, M., Kachi, M., 2003. Historical ocean subsurface temperature analysis with error estimates, Mon. Weather Rev., 131, 51–73.] and Levitus et al. (2005) [Levitus S., Antonov, J.I., Boyer, T.P., 2005. Warming of the world ocean, 1955–2003. Geophys. Res. Lett. 32, L02604. doi:10.1029/2004GL021592.]. When using the Levitus data, we observe very high thermosteric rates at sites located along the northeast coast of the US, north of 37°N. Such high rates are not observed with the Ishii data. Elsewhere, thermosteric rates agree reasonably well whatever the data set. Excluding the northeast US coastline sites north of 37°N, we compare tide gauge-based sea level trends with thermosteric trends and note that, in spite of a significant correlation, the latter are too small to explain the observed trends. After correcting for thermosteric sea level trends, residual (observed minus thermosteric) trends have an average value of 1.4 ± 0.5 mm/year, which should have an eustatic (i.e., due to ocean mass change) origin. This result supports the recent investigation by Miller and Douglas (2004) [Miller, L., Douglas, B.C., 2004. Mass and volume contributions to 20th century global sea level rise. Nature 428, 406–408.] which suggests that a dominant eustatic contribution is needed to explain the rate of sea level rise of the last decades observed by tide gauges, and shows that Cabanes et al. (2001) [Cabanes, C., Cazenave, A., Le Provost, C., 2001. Sea level rise during past 40 years determined from satellite and in situ observations. Science 294, 840–842.] arrived at an incorrect conclusion due to peculiarities in the gridded Levitus et al. (2000) [Levitus, S., Stephens, C., Antonov, J.I., and Boyer, T.P., 2000. Yearly and Year-Season Upper Ocean Temperature Anomaly Fields, 1948–1998. U.S. Gov. Printing Office, Washington, D.C. pp. 23.] data set.”

    [Response: Final line edited out. No need for gratuitous and inflammatory name-calling. The information is fine and people should work it into their discussion of sea level rise. Thanks for that. –raypierre]

    Comment by Richard Wakefield — 15 Jun 2008 @ 11:15 AM

  82. Regarding sea level rise,it’s important to remember that meltwater from floating sea ice and ice shelves don’t contribute to a rise. If you were to measure the surface level of a glass of water containing ice cubes before and after the cubes melt, the level remains the same.

    In other words the diminishment of the extent of the Arctic sea ice and the calving of ice shelves connected to continents don’t cause a rise in sea level, only melting ice that comes off of the land will do to this.

    Comment by Lawrence Brown — 15 Jun 2008 @ 11:27 AM

  83. Re 72:

    I went to your link, seen it before. This is rather revealing:
    “We have used a combination of historical tide-gauge data and satellite-altimeter data to estimate global averaged sea level change from 1870 to 2004. During this period, global-averaged sea level rose almost 20 cm, with an average rate of rise of about 1.7 mm/yr over the 20th Century. The sea level record indicates a statistically significant increase in the rate of rise between 1870 to 2004.”

    AGW claims the most increase was the past 50 years (since that is when the vast majority of FF use and human population growth occured), why would the change in sea level rise occur long before our CO2 emissions were significant? Also note the average. What is also interesting in that link is this:

    “This data has shown a more-or-less steady increase in Global Mean Sea Level (GMSL) of around 3.3 ± 0.4 mm/year over that period. This is more than 50% larger than the average value over the 20th century. Whether or not this represent a further increase in the rate of sea level rise is not yet certain.”

    This site is not linking any current small change to anything, including AGW. It is still a far cry from the rate needed by the alarmist positions. You need to at least double that rate just to make the lower end of the IPCC predictions.

    Re 70: Ray, you have no clue who I am or what I understand, but instead of dealing with the evidence, you instead fall back on the default position of anyone who has their dogma questioned — ad hominem attack. Models are not theories. Models are imperfect attempts to represent what is known and used to make predictions. All the hype about the alarmist future of the world due to CO2 emissions is from predictions based on these models, there is no guarantee these predictions will come true, but the holders of the polemic of AGW say it certainly is the future. Those people are flat wrong, and the future will show that as the planet does not behave as the “models” expect. In fact, the AGW community had to scramble to adjust their models because of the current no-warming trend since 1998, that was NOT predicted by the models.

    Thus I ask again, what will it take the planet to do to falsefy AGW theory?

    [Response: Your claim about the “AGW community” having to “scramble” etc. shows such a disconnect between the actual situation in the modelling community — to say nothing of the actual “trend” data — and your perception of it, that I can see why nobody here is taking you seriously. There is a real issue on the table with regard to the extent to which decadal fluctuations in the rate of sea level rise can be used to evaluate and improve the models, and the issues are there both with regard to modelling and to the nature of the data. I don’t see that your tendentious spin on this is contributing much to the discussion –raypierre]

    Comment by Richard Wakefield — 15 Jun 2008 @ 11:42 AM

  84. Mr. Pelto, thanks for the explanations. The second link in your comment #64, 14 June 2008, 0950, is the same as the first one to the Joughin and Bamber paper in GRL, about the Ronne-Filchner shelf. Should it not point to USGS data for the Ross shelf ?


    Comment by sidd — 15 Jun 2008 @ 11:58 AM

  85. Rob, how much of the CS Monitor article you cite did you actually read?

    Did you get as far as these two paragraphs, a ways down the page?

    “In 1993, we predicted that this was going to be a vulnerable ice shelf,” says David Vaughan of the British Antarctic Survey. “But we got the time scales completely wrong. We were saying 30 years at that time, and now it’s happened within 15.”

    Glaciologists are concerned about Antarctica’s ice shelves because most of them represent brakes of solid ice that slow the glaciers’ flow to the sea. Without those brakes, the glaciers would surge, calve into icebergs, and significantly raise the sea level.
    —–enc excerpt—-

    You read that, then ask “what’s the big deal?” — how?

    Comment by Hank Roberts — 15 Jun 2008 @ 12:26 PM

  86. [54] – There are suggestions that the Atlantic Meridional Overturning Circulation is in a strong phase. This is sometimes called the Atlantic Multi-Decadal Oscillation, which has been seen in long thousand year model runs, but the observations aren’t long enough to pin down its existence in the actual oceans.

    That would explain the north Atlantic warming faster than the south Atlantic.

    Also, some areas will warm faster than others simply due to noise. What is definitely not the case is that the northern hemisphere is warming up because the southern hemisphere is cooling down – ie a shift of heat from one to the other.

    However, the medieval warm period and little ice age look stronger [to my eye] in northern hemisphere only reconstructions than in global reconstructions, suggesting that could be a contributory factor explaining their prominence in the historical record.

    Comment by Timothy — 15 Jun 2008 @ 12:48 PM

  87. Re Rob’s “what’s the big deal” question in
    73: If the breakup of the Wilkins Ice Shelf were an isolated incident, we might be able to dismiss it.

    The reality is that the entire cryosphere is melting at an accelerating rate. The story Rob posted clearly puts the Wilkins breakup into context:

    Two of the 10 shelves along the peninsula have vanished within the past 30 years. Another five have lost between 60 percent and 92 percent of their original extent. Of the 10, Wilkins is the southernmost shelf in the area to start buckling under global warming’s effects. … Meanwhile, a team led by the Jet Propulsion Laboratory’s Eric Rignot published satellite radar data showing that while East Antarctica’s ice sheet lost virtually no mass between 1992 and 2006, the West Antarctic Ice Sheet was losing 132 billion tons of ice a year by the end of that period.

    Comment by Jim Galasyn — 15 Jun 2008 @ 12:54 PM

  88. Rob Huber (73) — According to orbital forcing theory, the globe should continue to slowly cool towards the next attempt at a stade (massive ice sheets) in about 20,000 more years. Instead, there is ample evidence that the warming in past 100+ years has undone the previous 7000 years or so of natural cooling. If Wilkins ice shelf is indeed relatively modern, this just supplied more evidence for that.

    Here is some of the other evidence.

    90–7000 years ago:

    5200 years ago:

    Comment by David B. Benson — 15 Jun 2008 @ 1:20 PM

  89. Richard Wakefield writes:
    > you have no clue about who I am or what I understand

    Without IP numbers no one can say one ‘Richard Wakefield’ is the same as another, but many by that name from Ontario post much alike, e.g.

    Comment by Hank Roberts — 15 Jun 2008 @ 4:39 PM

  90. Re Comments 80 and 82- Richard, there’s a Biblical expression, I believe, that states “Seek and Ye shall find.” Wan’t some evidence of the consistency of models with what’s really happening in the world? Then check this contributory post given(by Gavin) about James Hansens projections two decades ago and the match between observations and the model projections:

    There have been other tests of the validation of model consistency by running models forward from the past,which sucessfully reproduce the present day climate.and and the incorporation of Mt. Pinatubo into models, and the models,ensembles of them, have performed successfully in describing the global impact of this event, regarding temporary cooling.The models are also able to accurately show the vertical temperature changes in the atmosphere.

    If you look, you’ll find ample evidence of the validation of climate models.

    Comment by Lawrence Brown — 15 Jun 2008 @ 5:10 PM

  91. On sea level rise, Richard likes to cite: Berge-Nguyen, M., A. Cazenave, A. Lombard, W. Llovel, J. Viarre, and J.F. Cretaux. 2008. Reconstruction of past decades sea level using thermosteric sea level, tide gauge, satellite altimetry and ocean reanalysis data. Global and Planetary Change Vol. 62, No 1-2, pp. 1–13, May 2008

    The full paper is available here (if you have a subscription):

    From the abstract:

    “reconstructed spatial trends over 1993–2003 agree well with the regional sea level trends observed by Topex/Poseidon.”

    The links provided to the Topex/Poseidon data clearly show a sea level rise of 3.3 mm/year, almost double the rate from the 20th century.

    Here are a few other articles on sea level rise during the satellite era:

    “Sea Level Rise During Past 40 Years Determined from Satellite and in Situ Observations
    Cecile Cabanes, Anny Cazenave, Christian Le Provost

    The 3.2 ± 0.2 millimeter per year global mean sea level rise observed by the Topex/Poseidon satellite over 1993-98 is fully explained by thermal expansion of the oceans. For the period 1955-96, sea level rise derived from tide gauge data agrees well with thermal expansion computed at the same locations. However, we find that subsampling the thermosteric sea level at usual tide gauge positions leads to a thermosteric sea level rise twice as large as the “true” global mean. As a possible consequence, the 20th century sea level rise estimated from tide gauge records may have been overestimated.” Science 26 October 2001

    “A 20th century acceleration in global sea-level rise
    John A. Church1,2 and Neil J. White1,2

    Received 6 October 2005; revised 22 November 2005; accepted 1 December 2005; published 6 January 2006.
    [1] Multi-century sea-level records and climate models
    indicate an acceleration of sea-level rise, but no 20th
    century acceleration has previously been detected. A
    reconstruction of global sea level using tide-gauge data
    from 1950 to 2000 indicates a larger rate of rise after 1993
    and other periods of rapid sea-level rise but no significant
    acceleration over this period. Here, we extend the
    reconstruction of global mean sea level back to 1870 and
    find a sea-level rise from January 1870 to December 2004
    of 195 mm, a 20th century rate of sea-level rise of 1.7 ±
    0.3 mm yr1 and a significant acceleration of sea-level rise
    of 0.013 ± 0.006 mm yr2. This acceleration is an important
    confirmation of climate change simulations which show an
    acceleration not previously observed. If this acceleration
    remained constant then the 1990 to 2100 rise would range
    from 280 to 340 mm, consistent with projections in the
    IPCC TAR. Citation: Church, J. A., and N. J. White (2006), A
    20th century acceleration in global sea-level rise, Geophys. Res.
    Lett., 33, L01602, doi:10.1029/2005GL024826.”

    “Evidence for enhanced coastal sea level rise during the 1990s
    S. J. Holgate and P. L. Woodworth
    Proudman Oceanographic Laboratory, Bidston, UK
    Received 2 February 2004; accepted 11 March 2004; published 9 April 2004.

    [1] Sea level rise over the last 55 years is estimated to have
    been 1.7 ± 0.2 mm yr1, based upon 177 tide gauges divided
    into 13 regions with near global coverage and using a Glacial
    Isostatic Adjustment (GIA) model to correct for land
    movements. We present evidence from altimeter data that
    the rate of sea level rise around the global coastline was
    significantly in excess of the global average over the period
    1993–2002.We also show that the globally-averaged rate of
    coastal sea level rise for the decade centered on 1955 was
    significantly larger than any other decade during the past
    55 years. In some models of sea level rise, enhanced coastal
    rise is a pre-cursor of global average rise. It remains to be seen
    whether the models are correct and whether global-average
    rates in the future reflect the high rates of coastal rise
    observed during the 1990s. INDEX TERMS: 1635 Global
    Change: Oceans (4203); 1223 Geodesy and Gravity: Ocean/
    Earth/atmosphere interactions (3339); 4215 Oceanography:
    General: Climate and interannual variability (3309); 4556
    Oceanography: Physical: Sea level variations. Citation: Holgate,
    S. J., and P. L. Woodworth (2004), Evidence for enhanced coastal
    sea level rise during the 1990s, Geophys. Res. Lett., 31, L07305,
    1. Introduction
    [2] Global sea level is believed to have risen at a rate
    of 1–2 mm yr1 during the past 100 years, based on
    evidence from the sparse global tide gauge data set [Church
    et al., 2001]. On the other hand, analysis of near-global,
    precise radar altimetry has suggested a rate of rise nearer to
    3 mm yr1 for the past decade [Cabanes et al., 2001; Nerem
    and Mitchum, 2002; Leuliette et al., 2004]. At face value,
    this suggests a recent acceleration of the global sea level
    secular trend.”

    Comment by Ken Feldman — 15 Jun 2008 @ 5:16 PM

  92. Richard Wakefield,

    the reference for my numbers is directly from IPCC AR4 Chapter 5. I’d also add that the 3+ mm/yr is specifically for 1993-2003, which is distinct from “second half of the 20th century” in some of your papers.

    You have also not answered my question on why your sea level argument is constricted to the anthropogenic component in climate change. Does increasing the sun or decreasing cosmic rays or increasing martian galactic beams not raise temperature which raise sea levels? There are plenty of other metrics (instrumental record, glacier mass balance, etc) that demonstrate the globe is warming, and any causal agent which results in ice melt (which we know is happening) or thermal expansion should theoretically result in eustatic sea level rise.

    As for your insistence that models are the only thing we have to assess the future of climate change, you seem to be ignoring the radiative physics which extends back over a century and the quantification of 2x CO2 beginning with Arrhenius (which GCM did he have?) as well as the paleoclimatic record which unequivocally demonstrates the role of greenhouse gases in planetary climate.

    Of more importance than this quibbling, is the rapid loss of arctic sea ice, and breakup of various parts in Antarctica (Larson B, and now Wilkins) and as for sea-level contributing ice, the potential implications for eustatic sea level rise which may be greater than AR4 estimates, see

    Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century, Mark F. Meier, Mark B. Dyurgerov, Ursula K. Rick, Shad O’Neel, W. Tad Pfeffer, Robert S. Anderson, Suzanne P. Anderson, and Andrey F. Glazovsky (24 August 2007), Science 317 (5841), 1064. [DOI: 10.1126/science.1143906]

    Comment by Chris Colose — 15 Jun 2008 @ 5:34 PM

  93. George Tobin writes:

    why would anyone expect any significant AGW response at the poles?

    Google “ice-albedo feedback”

    Comment by Barton Paul Levenson — 16 Jun 2008 @ 6:20 AM

  94. Richard Wakefield posts:

    All the hype about the alarmist future of the world due to CO2 emissions is from predictions based on these models

    No, they are not. Global warming theory long predates computer models of its effects. Neither Arrhenius in 1896 nor Challenger in 1938 used computer models. From the increase in temperature expected from doubling CO2 and paleoclimate data about such changes in the past, the “alarmist future of the world” is logically implied.

    Comment by Barton Paul Levenson — 16 Jun 2008 @ 6:24 AM

  95. Wakefield is great bait. #80 asks a good question about melt rates. What we are observing in terms of breakup is both long term dynamics from progressive thinning due to long term warming, and short term melt. We have continued to see examples of very high melt in regions such as sw Greenland during the summer of 2007 and in regions of the Antarctic Peninsula. The hazard is that glacier dynamics pay attention to the long term, surface melt today is not that important to their current behavior. Hence, one a collapse begins, it is hard to slow down even if there is not additional warming.

    Comment by Mauri Pelto — 16 Jun 2008 @ 7:04 AM

  96. Has anyone published an estimate of what the rate of sea level rise would look like if there were not so much precipitation over Antarctica?

    Comment by Tenney Naumer — 16 Jun 2008 @ 11:09 AM

  97. An interesting thread. However, it seems to this observer that most, if not all, of the discussion is based on an assumption that increased break-up of the iceshelf is due to “warming”.

    However, it seems to me that the process could be much more complicated than that. For example, I can see scenarios where increased precipitation in the Anarctic creates increased snow loads, which causes the glaciation process to accelerate with more ice being delivered onto the surrounding oceans per unit time.

    Ice floating on seawater (by definition above the melting point of ice) experiences mechanical stresses leading to breakup. It may not necessarily be due to a simple conflation of warming = increased ice break-up.

    I am surprised in a whole thread that no one seems to consider these mechanical effects, although the lead post hints at it. Are they not a factor?

    Comment by Fair And Balanced — 16 Jun 2008 @ 2:40 PM

  98. Fair and Balanced, I don’t think your theory passes muster. First, we wouldn’t have increased precipitation if we didn’t have warming and more evaporation. Second, the precipitation is mostly taking place far inland, and so is exerting little direct pressure on the ice shelf.

    Comment by Ray Ladbury — 16 Jun 2008 @ 3:53 PM

  99. Fair and Balanced, if the issue were increased glacial flow due to increased snowfall, Why would the leading edge of the ice sheets be retreating rather than simply melting faster to stay in place (if not advancing)?

    Comment by Arch Stanton — 16 Jun 2008 @ 5:06 PM

  100. #96 Tenney,

    Davis et al (2005) in Science suggest that Antarctic gain from 1992 to 2003 may have slowed sea level rise by roughly 0.12 mm/yr. This is roughly the same time period (1993-2003) that IPCC says increased 3.1 mm/yr.

    Comment by Chris Colose — 16 Jun 2008 @ 11:34 PM

  101. Re 97-99, please see

    Thomas, Elisabeth R., Gareth J. Marshall, and Joseph R. McConnell, 2008. A doubling in snow accumulation in the western Antarctic Peninsula since 1850. Geophys. Res. Lett., 35, L01706, doi:10.1029/2007GL032529, January 12, 2008


    We present results from a new medium depth (136 metres) ice core drilled in a high accumulation site (73.59°S, 70.36°W) on the south-western Antarctic Peninsula during 2007. The Gomez record reveals a doubling of accumulation since the 1850s, from a decadal average of 0.49 mweq y−1 in 1855–1864 to 1.10 mweq y−1 in 1997–2006, with acceleration in recent decades. Comparison with published accumulation records indicates that this rapid increase is the largest observed across the region. Evaluation of the relationships between Gomez accumulation and the primary modes of atmospheric circulation variability reveals a strong, temporally stable and positive relationship with the Southern Annular Mode (SAM). Furthermore, the SAM is demonstrated to be a primary factor in governing decadal variability of accumulation at the core site (r = 0.66). The association between Gomez accumulation and ENSO is complex: while sometimes statistically significant, the relationship is not temporally stable. Thus, at decadal scales we can utilise the Gomez accumulation as a suitable proxy for SAM variability but not for ENSO.

    Further, the IPCC estimates “Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.”

    Comment by Timo Hämeranta — 17 Jun 2008 @ 1:15 AM

  102. Re: #100

    Thank you, Chris!

    Re: #101

    The paragraph from the IPCC is rather cold comfort as the latest research shows a negative mass balance primarily from losses at WAIS, does it not?

    Comment by Tenney Naumer — 17 Jun 2008 @ 8:03 AM

  103. Re # 102, Tenney, please see

    Helsen, Michiel M., Michiel R. van den Broeke, Roderik S. W. van de Wal, Willem Jan van de Berg, Erik van Meijgaard, Curt H. Davis, Yonghong Li, and Ian Goodwin, 2008. Elevation Changes in Antarctica Mainly Determined by Accumulation Variability. Science, published online before print May 29 2008


    Antarctic ice sheet elevation changes, which are used to estimate changes in the mass of the interior regions, are caused by variations in the depth of the firn layer. Here we quantify the effects of temperature and accumulation variability on firn layer thickness, by simulating the 1980–2004 Antarctic firn depth variability. We demonstrate that, for most of Antarctica, firn depth changes are of comparable magnitude as observed ice sheet elevation changes. The current satellite observational period (~15 years) is too short to neglect these fluctuations in firn depth when computing recent ice sheet mass changes. The amount of surface lowering in the Amundsen Sea Embayment revealed by satellite radar altimetry (1995–2003) is increased by including firn depth fluctuations, while a large area of the East Antarctic ice sheet slowly grew due to increased accumulation.

    Comment by Timo Hämeranta — 17 Jun 2008 @ 10:55 AM

  104. Further Re 102 Tenney,

    you refer to the study

    Rignot, Eric, Jonathan L. Bamber, Michiel R. van den Broeke, Curt Davis, Yonghong Li, Willem Jan van de Berg, and Erik van Meijgaard, 2008. Recent Antarctic ice mass loss from radar interferometry and regional climate modelling. Nature Geoscience Vol. 1, No 2, pp. 106-110, February 2008, online

    “Observed estimates of ice losses in Antarctica combined with regional modelling of ice accumulation in the interior suggest that East Antarctica is close to a balanced mass budget, but large losses of ice occur in the narrow outlet channels of West Antarctic glaciers and at the northern tip of the Antarctic peninsula.”

    Please notice Andrew Shepherd’s comment in Nature News Jan 13, 2008:

    “Shepherd cautions that Rignot’s three-point trend shouldn’t be projected decades into the future, because there’s reason to believe that the increasing amount of cold meltwater near the coast might slow further losses.”

    Finally please see also:

    Zhang, Jinlun, 2007. Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions. Journal of Climate Vol. 20, No 11, pp. 2515–2529, June 2007


    Estimates of sea ice extent based on satellite observations show an increasing Antarctic sea ice cover from 1979 to 2004 even though in situ observations show a prevailing warming trend in both the atmosphere and the ocean. This riddle is explored here using a global multicategory thickness and enthalpy distribution sea ice model coupled to an ocean model. Forced by the NCEP–NCAR reanalysis data, the model simulates an increase of 0.20 × 1012 m3 yr−1 (1.0% yr−1) in total Antarctic sea ice volume and 0.084 × 1012 m2 yr−1 (0.6% yr−1) in sea ice extent from 1979 to 2004 when the satellite observations show an increase of 0.027 × 1012 m2 yr−1 (0.2% yr−1) in sea ice extent during the same period. The model shows that an increase in surface air temperature and downward longwave radiation results in an increase in the upper-ocean temperature and a decrease in sea ice growth, leading to a decrease in salt rejection from ice, in the upper-ocean salinity, and in the upper-ocean density. The reduced salt rejection and upper-ocean density and the enhanced thermohaline stratification tend to suppress convective overturning, leading to a decrease in the upward ocean heat transport and the ocean heat flux available to melt sea ice. The ice melting from ocean heat flux decreases faster than the ice growth does in the weakly stratified Southern Ocean, leading to an increase in the net ice production and hence an increase in ice mass. This mechanism is the main reason why the Antarctic sea ice has increased in spite of warming conditions both above and below during the period 1979–2004 and the extended period 1948–2004.

    Comment by Timo Hämeranta — 17 Jun 2008 @ 11:08 AM

  105. “Fair and Balanced” wrote:

    > Ice floating on seawater (by definition
    > above the melting point of ice)

    What’s your source for this belief?
    Why do you believe it? Have you looked it up?

    Comment by Hank Roberts — 17 Jun 2008 @ 1:05 PM

  106. Timo Hämeranta wrote in comment #104 at 17 June 2008 at 1108:

    Zhang, Jinlun, 2007. Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions. Journal of Climate Vol. 20, No 11, pp. 2515–2529, June 2007

    Thank you for directing me to this paper. If I read it correctly, Mr. Zhang has a model where increased Southern sea ice occurs together with increasing air and ocean temperatures, increased stratification and decreased upper layer salinity. I was hoping that the paper might contain some observational data on stratification and salinity, but I did not see any. Would you (or any one else) by any chance be aware of work in that area ?


    Comment by sidd — 17 Jun 2008 @ 3:53 PM

  107. NASA Mission Poised to Help Us Gauge Our Rising Seas

    “We know the basics of sea level rise very well,” said JPL oceanographer and climate scientist Josh Willis. But several critical elements still need to be resolved, he stressed. “Everything doesn’t quite add up yet.”

    For example, in a recent study, Willis, Chambers and their colleague Steven Nerem of the Colorado Center for Astrodynamics Research in Boulder, compared the amount of ocean warming during 2003 to 2007 observed by the Argo buoys with the amount of warming calculated by combining Grace and Jason-1 altimeter data. While the two measurements closely matched with regard to seasonal ups and downs, they didn’t agree at all on the total amount of warming. In fact, the Argo data showed no warming at all, while the combined Jason and Grace data did.

    This is a mystery to the scientists, which they hope to resolve soon. Willis added there is no observing system yet for the deep ocean, and it could hold some real surprises.

    The record of sea-surface height begun by Topex/Poseidon is now 16 years old. As the record grows longer with the continued health of Jason-1 and the launch of OSTM/Jason-2, some uncertainties about sea level rise are much closer to resolution.

    “We are getting a better understanding of our measurement systems and just how much we can trust our numbers,” said Fu. “We know that sea level is not rising everywhere at the same pace, and we are learning more every year about the natural variability in the ocean over short and long periods. We are learning more about the exchange of heat between the ocean and the atmosphere, the driving force of our climate.”

    So will we have disastrous sea-level rise? If so, when?

    We don’t know yet, said Fu, but he does not rule out finding the answer.

    Comment by Richard Wakefield — 17 Jun 2008 @ 5:43 PM

  108. Re # 106 sidd,

    hope this one helps, a bit at least:

    Sigman, Daniel M., Samuel L. Jaccard and Gerald H. Haug, 2004. Polar ocean stratification in a cold climate. Nature Vol. 428, No 6978, pp. 59-63, March 4, 2004, online

    Re 107 Richard,

    additionally please see the studies

    1) Wöppelmann, Guy, B. Martin Miguez, M.-N. Bouin, and Z. Altamimi, 2007. Geocentric sea-level trend estimates from GPS analyses at relevant tide gauges world-wide. Global and Planetary Change Vol. 57, No 3-4, pp. 396-406, June 2007, online

    “5. Conclusions

    Munk (2002) stressed that the sum of climate-related
    contributions to sea-level change was low (0.7 mm/yr)
    compared to the observations over the last 50–100 years
    (1.8 mm/yr) by referring to this factor 2 difference as the
    ‘enigma’ of sea-level change. Since then, the more
    recent results now indicate a 1 mm/yr contribution from
    the melting of global land ice reservoirs (Mitrovica
    et al., 2006), as well as a 0.4 mm/yr contribution from
    the thermal expansion of the world ocean (Antonov
    et al., 2005). We show here an exercise of combining
    GPS and tide gauge results that reduces the global average
    sea-level rise to 1.3 mm/yr. This appears to
    resolve the sea-level enigma….”

    The important contribution of Wöppelmann et al. is the inclusion of land motions (e.g. postglacial rebound) to the sea level calculations and widening the observational area also to two additional regions, namely ‘Northern Europe’ and ‘NW North America’. All those together reduces the mean rise from 1,8 mm/yr to 1,31 ± 0.30 mm/yr in the last 100 years.

    2) Johnson, Gregory C., Sabine Mecking, Bernadette M. Sloyan, and Susan E. Wijffels, 2007. Recent Bottom Water Warming in the Pacific Ocean. Journal of Climate Vol. 20, No 21, pp. 5365-5375, November 2007, online

    “… Rough estimates of the change in ocean heat content suggest that the abyssal warming may amount to a significant fraction of upper World Ocean heat gain over the past few decades.”

    Yes, “we are learning more every year about the natural variability in the ocean over short and long periods…”

    Comment by Timo Hämeranta — 18 Jun 2008 @ 2:24 AM

  109. Sorry to use news media as sources, but I note acceleration in the year predicted for an ice free Arctic Summer.

    Today it is: “Arctic Ocean expected to be ice free this September. For the first time in 100,000 years.”

    In 2005, the prediction was 100 years – then in 2006 it was 35 years, and now 2008 for an ice free Arctic.

    Is there a source for tracking the changes in models? Or links to model updates? It seems like we need rapid updates.

    ===URL snips:=== this summer 2008 ========
    Researchers predict ice-free North Pole this year
    Nunatsiaq News | May 23, 2008 | JANE GEORGE
    Here’s the good news: this summer’s Arctic ice melt means an early start to the Hudson Bay shipping season.
    Forecasts show Coast Guard icebreakers will no longer be necessary for shipping to Churchill after July 16.
    That’s 15 days earlier than the average ice-free shipping date of July 31, which means re-supply barges should able to reach communities in Nunavut’s Kivalliq and Kitikmeot regions that much earlier.
    But the down side to the retreat of the Arctic’s thin ice cover is a 50-50 chance that the North Pole will become ice-free this September – for the first time in more than 100,000 years…

    ======= 2006 ===========
    Abrupt Ice Retreat Could Produce Ice-Free Arctic Summers by 2040
    December 11, 2006
    BOULDER—The recent retreat of Arctic sea ice is likely to accelerate so rapidly that the Arctic Ocean could become nearly devoid of ice during summertime as early as 2040, according to new research published in the December 12 issue of Geophysical Research Letters…

    ======== 2005 =================
    Arctic Ocean Could Be Ice-free In Summer Within 100 Years, Scientists Say
    ScienceDaily (Aug. 24, 2005) — The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and a team of researchers were unable to identify any natural processes that might slow the de-icing of the Arctic…


    Uh oh, I feel a graph coming on.

    Comment by Richard Pauli — 18 Jun 2008 @ 9:23 PM

  110. Re #109

    Here is a link to Richard Pauli’s news story Researchers predict ice-free North Pole this year.

    Note that Mark Serreze is only implying that there may be no ice between the North Pole and the North Atlantic, not an ice free Arctic. He say that “… only 2.22 million sq km of ice – less than the size of Nunavut – will remain in the Arctic Ocean this September. This would be much less than the record low of 4.28 million sq km set in 2007.”

    There is another report on the Arctic ice from the BBC: Arctic sea ice melt ‘even faster’. But it may be a little premature. It seems to be based on this chart of Arctic Sea Ice extent, which does show a steeper decline in sea ice extent during April and early May, but for the last month the rate of decline recorded last year and this year have been virtually the same.

    The question is what will happen when the ice reaches the tipping point at the end of June and the retreat steepens?

    Cheers, Alastair.

    Comment by Alastair McDonald — 19 Jun 2008 @ 4:20 AM

  111. Alastair,

    That’s not a bad article, but Stroeve’s considerations are much more complex than just that chart. It’s worth reading the expert outlook submissions from Arcus, available as one pdf from here:

    Comment by Cobblyworlds — 19 Jun 2008 @ 8:19 AM

  112. Reading the NASA-GISS website it seems that apart from the West Antatctic peninsula all the above average temperatures in the Antartic seem to happen in winter. In the SH summers it seems either normal or colder. Has anybody else noticed this?

    Comment by D Price — 19 Jun 2008 @ 10:34 AM

  113. Re #83 Richard Wakefield

    You state:

    “Re 70: Ray, you have no clue who I am or what I understand, but instead of dealing with the evidence, you instead fall back on the default position of anyone who has their dogma questioned”.

    You seem to be stating your bias in a Freudian sense, that you are more interested in dogma than reason. Your problem may lie in the fact that your idea of evidence is to narrowly limited or narrowly scoped. Biased views are common, though not always contributive until weighed in the aggregate of understanding.

    Ray merely pointed out apparent gaps in your reasoning as stated.

    It is pretty easy to oversimplify any argument in discussing AGW due to the mass of data and developing understanding.

    As to your “Models are imperfect attempts to represent what is known and used to make predictions. All the hype about the alarmist future…”

    You are missing some points. Models are developed to help understand observations as understood. Models are then refined and confirmed to the greatest degree possible. Models are never perfect, because they are intrinsically models and a useful tool for understanding. Without models modern development would be more slow and we would likely live in a less technologically advanced world.

    The other part that seems to be missing in your argument is that the observations are becoming more revealing than the models. There is a lot of confirmation going on in the manifestation based on what was expected from the models.

    If you approach this from relevant holistic reasoning, you might actually see the potentials not only in the future but what is actually happening on the planet right now. There are a lot of pieces to this puzzle and it seems you are not examining enough pieces to make claims, which is the basic problem with your argument.

    Your last statement “the AGW community had to scramble to adjust their models because of the current no-warming trend since 1998” indicates a fundamental misunderstanding of the short and long term implications of climate forcing, not to mention your negation of the fact that we are at the bottom of the 11.1 year solar cycle and were in La Nina last year. Less forcing would be expected to reduce the temperature positive forcing. And of course you need to recognize that the 1998 El Nino event was unusually strong which set up the short term trend line.

    Fundamentally, you need to understand that climate is not weather and that short term views to not imply long term trends.

    Here is what you can likely expect based on the observed trends and expectations. The solar cycle will go back up in positive phase adding .3 W/m2 to the forcing and we will have another El Nino event. Expect some records to be broken in the GMT over the next 3 to 7 years and the Arctic Ice to reach at or near zero ice in that period as well during the minimum ice phase of the melt cycle.

    Your final statement “Thus I ask again, what will it take the planet to do to falsefy AGW theory?” indicates a rather complete misunderstanding of this particular global warming event and its drivers outside of the natural cycles.

    There are a multitude of problems with the question.

    First: and most obvious, the planet can not falsify the AGW theory. Although I sort of understand what you are trying to say it’s kind of a weird question.

    Second: Since the observations and the models are in agreement on a wide array of assessment perspectives “the planet” can’t prove the AGW theory wrong.

    Third: It is fairly obvious you are merely barking up the wrong tree or you have not checked out enough trees in the forest of climate science. If you examine only a few trees in the forest rather that a relevant sampling of the trees in the forest, you not only will not see the forest through the trees, you can’t see the forest through the tree, so to speak… It is fairly obvious, based on the arguments you have presented that the forest is bigger than you think.

    Comment by John P. Reisman (The Centrist Party) — 22 Jun 2008 @ 2:48 PM

  114. Re #111 where Cobblyworlds Says:


    That’s not a bad article, but Stroeve’s considerations are much more complex than just that chart. It’s worth reading the expert outlook submissions from Arcus, available as one pdf from here:


    Thnks for the link to the full article. It is very interesting but the point I was trying to make was not about the imminent disappearance of the Arctic sea ice permanently. I was really trying to say that just as the Antarctic ice shelves collapse suddenly, so does the Arctic sea ice. Around about the end of Jult, the meltwater which has been forming pools, eats its way through the ice and the ice begins to retreat more quickly. The accelerating melt can be seen clearly last year on the chart I linked to.

    Annual acceleration is not so obvious because it has been averaged away, but it can still be detected. I wonder whether the Antarctic ice experts are aware of this common feature.

    Cheers, Alastair.

    Comment by Alastair McDonald — 23 Jun 2008 @ 4:32 PM

  115. Re: comments #102 and #103

    Dear Timo,

    First, thank you for supplying those leads. I would have thanked you sooner but I have been a bit under the weather (or climate, as the case may be).

    Second, I would like to call upon you, raypierre, Chris, and Hank to come over to Dot Earth where we are being besieged by the industry-paid denialists due to Andy’s recent hammering on the realities of climate change and then of course Dr. Hansen’s speech, today, not to mention that Andy raised the point of whether or not the oil and coal executives should be considered criminals against nature.

    Please help at:

    and the 3 or 4 other threads since that one.

    Thank you.

    Comment by Tenney Naumer — 23 Jun 2008 @ 9:25 PM

  116. Tenny, if the NYT wanted a fact checker involved they’d provide one as a fair witness. Good science reference desk help isn’t hard to find. Whatever their business model is over there, education isn’t in it.

    Comment by Hank Roberts — 23 Jun 2008 @ 10:45 PM

  117. Re: comment #116

    Dear Hank,

    Fact checking is not the point. We know that there are industry-paid bloggers whose purpose is to delay any action on reducing CO2 emissions. It is our responsibility to present the truth and combat their efforts, efforts that have been exceedingly successful for the past 20 years, as you may have noticed.

    We are not talking about a business model here. We are talking about the sad fact that public opinion has been so manipulated that most people have no idea that global warming is a matter of the utmost urgency for all of us.

    There are plenty of readers of Dot Earth who are newbies to this issue and don’t know what to read or believe or where to even start.

    I am not a trained scientist — I have to teach myself all of this from scratch, while many bloggers here at realclimate are immersed in this subject and have all the correct arguments at hand. Therefore, it is not that much of a burden for realclimate bloggers to help out, in my not so humble opinion.

    And, what, after all, is the purpose of the realclimate blog?

    If I can spend 10 hours a day trying to help these readers, then real scientists from realclimate could spend 30 minutes of their time, surely.

    Comment by Tenney Naumer — 24 Jun 2008 @ 11:02 AM

  118. Re: #117 Tenny

    You stated:

    “And, what, after all, is the purpose of the realclimate blog? If I can spend 10 hours a day trying to help these readers, then real scientists from realclimate could spend 30 minutes of their time, surely.”

    I’d be willing to bet the scientists are doing more than 10 hours a day on climate. So to ask them for another 30 minutes is more than you may think. Because it’s not just 30 minutes you are asking for. For them to review and track the issues in your blog would likely take much more than 30 minutes a day because to review arguments you have to review all the arguments.

    The scientists are busy doing what they need to do and have committed tremendous time and effort to getting it right. They are doing their best and generally I think their time is best spent on doing the science rather than chasing down every single blog argument.

    I can speak for myself and maybe others would agree. We can help by bringing the relevant arguments to the people in our sphere of influence such as your blog.

    Read, study, learn and go back and do your best to answer the questions or better yet, point them to the RC articles that deal with the question at hand. I think it is unfair to pose such a challenge to those that are already working so hard. Asking for 30 minutes a day is a lot.

    I tell everyone I talk to to go to RC is the best climate science one stop you can find.

    Comment by John P. Reisman (The Centrist Party) — 24 Jun 2008 @ 8:15 PM

  119. Let me be a little more blunt here. I am self-employed. Since I gave myself the task of fighting the EXXON-financed denialists, 8 months ago, I have not worked for myself. This is my choice, of course.

    Don’t imagine that I am a johnny-come-lately to science. I started out in science but ended up with two master’s degrees in business, instead.

    It is not that difficult to come over to Dot Earth once in a while.

    You guys can carry on your polite genteel discussions here, although we all know that almost all of the denialist arguments have been completely debunked and now we are just getting into some of the finer points.

    Dot Earth is not my blog. It belongs to the New York Times. Apparently, EXXON considers it important enough to send over scads of people to confuse the issue in the public’s mind.

    Dr. Hansen issued a clarion call 20 years ago — since then the public has become even more confused.

    The onus is on all scientists to help. Time is short.

    The Wall Street Journal also has chat pages — this is one more venue that should be used.

    btw, it is Tenney, with two e’s

    Comment by Tenney Naumer — 25 Jun 2008 @ 12:39 AM

  120. Tenny I appreciate your tenacity in blogging. As a glaciologist it is my job to educate the public. I find this is not possible by blogging at Dot Earth, where the noise to signal ratio is just too high, it was not several months ago. may get there, but for now the signal is higher than the noise. For the post here on ice shelves, it took about 30 hours of scrutiny of the key articles, after twenty five years of work in the topic area, to put together this piece. This is time well spent I feel, but does not earn a scientist any professional points. I do spend 30 minutes a day reading the material at these sites to remain educated in the realms that are not my specialty. It is amazing how informative at least the links are provided by the blogging public.

    Comment by Mauri Pelto — 25 Jun 2008 @ 7:12 AM

  121. Tenney,

    One top scientist is speaking out, but not on blogs that are only read by at most a few hundred people. James Hansen has now woken up to the problem. See Warming Scientist: ‘Last Chance’ where he says:

    “We’re toast if we don’t get on a very different path,” Hansen, director of the Goddard Institute of Space Sciences who is sometimes called the godfather of global warming science, told The Associated Press. “This is the LAST chance.” [My emphasis]

    The problem is that most climate scientist do not see the dangers. They are wrapped up in their own little specialty and don’t feel qualified to speak outside their field. And those who post here just cannot bring themselves to believe that the situation is as critical as it is. For instance, David wrote in James Lovelock’s Gloomy Vision

    “No one, not Lovelock or anyone else, has proposed a specific, quantitative scenario for a climate-driven, all out, blow the doors off, civilization ending catastrophe. …I think in general the consensus gut feeling among small-minded working scientists like me is that the odds of such a catastrophe are low.”

    Yet Lovelock had written that we could be heading for a minor mass extinction similar to that which happened during the Paleo-Eocene Thermal Maximum, with the few human survivors living on along the Arctic coast.

    Good luck with you mission, but I doubt you will get much help from the scientists until they too see the dangers. And of course, their doubts undermine your advocacy as they add to support to the skeptical argument that the science is still undecided :-(

    Cheers, Alastair.

    Comment by Alastair McDonald — 25 Jun 2008 @ 11:03 AM

  122. Tenney, as a scientist who has tilted at my share of windmills of scientific ignorance, I sympathize. The problem is that on a source like dot Earth, posters are anonymous, so claims of expertise cannot be assesses. Moreover, the average reader in such forums is incapable of assessing who is really an expert. I do post there, but I’m afraid it’s a bit of a scientific cesspit.

    Comment by Ray Ladbury — 25 Jun 2008 @ 11:05 AM

  123. Alastair, I don’t think the problem is that scientists are unaware of the risk. Rather, they simply despair of making a difference in forums where any jackass can claim to be a frigging Nobel Laureate and where the average reader is scientifically illiterate. That is why sites like Realclimate and ClimateProgress serve as refuges for those who are serious.
    Science has never worked as an evangelical enterprise. Since it requires work for people to understand scientific truth, they need to have the commitment of seeking it out rather than having it broadcast to them.

    Comment by Ray Ladbury — 25 Jun 2008 @ 12:13 PM

  124. Re: #120 Mauri

    I appreciate your signal to noise analogy, and your work on a vary informative article :)

    I believe that the noise level is precisely what has kept the argument confused for the past 20 years.

    Increasing signal strength is happening on an individual basis but prescience is not the forte of a society inundated with noise. On an individual basis the signal is getting through. Reason and relevance and context are the keys I find work but one must be able to answer the questions and provide sources.

    Re: #119 Tenney

    I hear you. In fact I empathize with you. I also think that this is a great place for you to blog but if I were you, and I’m not, I would advise another tactic in your responses.

    Many people of their own initiative are dedicating time and energy to the issue of awareness. And time is short, but reasonable polite argument can go a long way.

    It’s a simple matter of continuing to answer the questions and thereby continually raising awareness of the issues at hand. Impolite arguments tend to put up walls and cause people to solidify their beliefs in a non-scientific position. I encourage you to be polite and address the arguments with the truth of what is known. I’m still learning too, it’s not like this ever ends.

    I read some of your posts on Dot Earth. You seem to be addressing issues with the politic rather than the science. In one post you say two people “are seen for the jokes that they are ” and in another you chastise someone saying “Do we need that type of remark here, really?” I think the old you can catch more flies with honey thing could help here. Always address a concern with the relevant answer and instead of fighting more people will have the opportunity to learn.

    You have a great opportunity. When someone says something, respond, but go to RC first and look up relevant articles and post the links. That would help lead people to review the argument themselves. Remember, it’s not just the people you are talking to but those that read the posts as well. When you respond, use the opportunity to reach more people with good information. I apologize if I sound to instructive but that has been part of my career. I only mean to encourage you and all to refine the argument in order to achieve relevant understanding.

    Re #121 Alastair

    You have made a good point. Scientists typically don’t speak outside their field (part of the training I believe).

    The dangers are reasonably obvious regarding expected trends when viewed through aggregate reasoning of relevant spheres of influence of the climate forcing.

    I continue to believe that individual awareness will drive the policy. More people need to understand the ramifications and as human history has pointed out, we are typically not prescient as a general rule.

    General awareness, in my opinion will lead to policy shifts. Unfortunately, waiting for this to occur only exacerbates the problem through additional climate forcing i.e. future warming due to forcing levels and oceanic thermal lag time and latent inertia.

    I have noticed even amongst my more conservative friends that it does sink in if one argues with real science and addresses the political arguments and the disinformation simultaneously; it just doesn’t go very fast due to the nature of beliefs v. lack of awareness of relevant knowledge in context.

    Comment by John P. Reisman (The Centrist Party) — 25 Jun 2008 @ 2:27 PM

  125. John,

    You wrote “it just doesn’t go very fast …” but that is the problem. We have now run out of time!

    As Margaret Beckett said on the BBC’s Newsnight programme tonight everyone thinks that it is a problem for our children and grndchildren to solve, but it is we who are going to suffer.

    Taking a centrist attitude may be correct when making political decisions, but not if there is a catastrophe is looming.

    Cheers, Alastair.

    Comment by Abbe Mac — 25 Jun 2008 @ 5:16 PM

  126. Re: #125


    I fully agree with you.

    So I am working on some new strategies to get the relevant understanding out. I hope to be able to share that with you soon. The disinformation campaign has been very successful in America, Norway and Great Britain; and moderately successful elsewhere.

    This is a ‘Right Now’ problem!

    But if I yell at people that don’t agree with the relevant science, they will say I am an alarmist, close their minds a little more, and tell their friends John has gone off the deep end.

    Since those that are adamant about it not being human caused are the target for the relevant understanding, then the onus of responsibility is upon us to communicate in the most effective, therefore the most expedient manner to achieve the goal of understanding of the relevant science.

    But that is just my opinion.

    Best, John

    Comment by John P. Reisman (The Centrist Party) — 25 Jun 2008 @ 6:57 PM

  127. Re: 124

    Dear John,

    The Dot Earth blog is getting more than 200,000 hits per month now.

    My responses on Dot Earth tend to be related entirely to whether the person I am talking at has already posted 30 comments of BS in two days, whether I can detect that the person is a paid denialist (not difficult to figure out), whether the person is a newbee, and whether I am tired and out of sorts and/or just plain exhausted from repeating myself. The paid denialists will not be convinced by anything I write because they are not there for that. Yes, sometimes, I get pretty sharp with people, but only the paid denialists.

    I will tell you something else — the fact that I have come out very strongly has given other commenters the courage to come out and take a stand in their own way, albeit in a somewhat milder manner.

    I maintain a blog (just click on my name to see the reference blog) with relevant scientific data, graphs, abstracts, articles, sites, etc., and in my comments I often refer to the links in it or to the site. It is getting about 2000 hits per month now, which is nothing compared to realclimate, of course, but volume is growing rapidly.

    I am constantly perusing sites on the net in order to keep up to date on the research.

    I do not send people to realclimate because it is generally over their heads.

    I do, however, often send people to Tamino’s blog since he posts the best graphs of the data.

    We have only 6 months to try to get the truth out to the public and have them understand the absolute seriousness of the problem before the next president takes office because the next president needs to act during his “honeymoon” period.

    Even a new president is not going to do anything on climate change if the public is badly informed and against it.

    Dr. Hansen has really stuck his neck out and basically is hanging in the wind right now. Is the scientific community going to just leave him there?

    You would not even have to argue with any of the comments, all you have to do is post a comment saying that you are who you are and that you think that the time has come to get on with reducing emissions or we are all going to end up toast or whatever.

    That wouldn’t even take 30 minutes, it might take only 10.

    I think that any tenured professor who has ever taught an intro course should be able to make simple comments on Dot Earth that refute the paid denialists.

    If real scientists are content to sit back and let the fossil-fuel industry win this struggle, then there is not much hope for the rest of us.

    Comment by Tenney Naumer — 25 Jun 2008 @ 7:04 PM

  128. Dear John,

    The “Do we need that type of remark here, really?” was my way of nudging Steve Bolger who is an old-timer on Dot Earth, like myself — he made a comment that implied that more people would be committing suicide as a result of the hopeless of the situation — that type of comment is generally considered to be very bad form on Dot Earth and I was merely reminding him. I am reasonably sure that he knew exactly what I meant and took it to heart.

    I am certainly very rude to the denialists — they are not there to listen to anyone or to be persuaded. No doubt this puts off some readers while encouraging others. Usually, I back up what I say with data or sites or cites, but not always, depending on how much time I have.

    There are obvious skeptics who lack the knowledge and who are willing to become more informed. Some of them are even coming around or have completely come around. I treat them with kid gloves (well, generally). I invite them to take it offline and we discuss by e-mail.

    Long-term genuine, sincere skeptics who will not be convinced I leave entirely alone.

    Thus, my focus is on the paid denialists and the skeptics who are willing to learn.

    What is now required is a strong signal rising above the noise — one person cannot do it alone.

    But the time is now, and the time is ripe.

    If I did not believe this, I would not be here making this request.

    Comment by Tenney Naumer — 25 Jun 2008 @ 7:38 PM

  129. Re: #127


    I think your on the general right track as far as getting the message out. I’m curious, do you actually have proof that there are paid denialists? I think maybe there are but I would not accuse anyone without proof. I just present the relevant data in context so people can see a better perspective.

    I’ve got a good track record. I can typically turn someone around in 5 to 15 minutes of Q&A. I know being rude does not work with anyone from my experience and what I have seen. I understand you are only rude to certain people.

    Maybe, rather than being rude though, you present the science in context for the argument at hand. It is always easy to have a spitting match of conjectures, but facts are pretty hard to refute.

    Mostly they present air-balls that can go nowhere anyway. So when they do, I just lay some concrete at their feet and let them decide if its solid or not. All I can say is that I have noticed that I make a lot of progress that way. You can do the same.

    I don’t know if I agree that Dr. Hansen has stuck his head out or not, maybe in some ways? but I know he is sitting on a mountain of data that supports his context in the argument and I don’t think it is possible for anyone to legitimately refute the claims. He is diplomatic and strong in his assertions and his perspective, as far as I can tell, has no holes in his statement. Personally, I think he is standing on very solid ground in the debate.

    The relevant scientists are not, in my opinion, content to sit back and let the fossil-fuel industry win this struggle. There is a good method occurring here and it is getting stronger every day. I predict that before November, we will see a sea change in understanding. That will be due to a multitude of reasons in my opinion but we are all here to help people understand so the political motivation is strong come next January.

    Keep bringing reason to the table and there will be little room for ignorance. I don’t think the battle will be lost just because relevant scientists did not blog on Dot Earth. It will only be lost if we give up reason itself. That’s not to say some scientists don’t blog there already as is noted above by Ray Ladbury mentioned in comment #122.

    Keep up the relevant arguments.


    Comment by John P. Reisman (The Centrist Party) — 25 Jun 2008 @ 10:35 PM

  130. Dear John,

    It is well documented that Exxon is paying certain organizations, just google: marshall institute tobacco climate

    The paid deniers all use the same fallacious arguments — they are quite consistent about it. You can politely show them the error of their thoughts with complete cites and graphs and whatever, but they come back like bad pennies over and over again with the same stuff — one of their favorites is: “It’s the sun!” Another is: “the planet is cooling — no temperature increases since 1998” or “It was hotter in 1934” (for a complete list and their refutations, go to

    It is also well known that certain right-wing strategists have been using psychological tactics to influence public opinion. These same tactics are being used by the fossil-fuel industry. Essentially, these involve inspiring fear in the reader — examples are: the economy will be destroyed by being forced to switch to new energy sources, and environmentalists want to effect a transfer of wealth.

    Then, there are the more subtle insinuations, e.g., we should all wait and remain calm until the science is settled, or we should wait because technological improvements over the next 20 years will doubtless solve the problem for us.

    Even more subtle are the ones who start out thusly: “I am a scientist and I think we should reduce CO2, but the science is not settled yet and we should be cautious — just look at the disaster of renewables from corn…” However, it soon becomes clear from the rest of the comment that the writer is no kind of scientist.

    Trust me — after 8 months of this, I have seen them all.

    Let me tell you something about Joe Q Public. It is not necessary to teach him the science. He just needs to see that people he can respect and look up to have come out in agreement and they speak louder than the denialists. Joe Q Public will remain ignorant. That’s OK.

    But he needs to see scientists taking a public stand.

    Comment by Tenney Naumer — 25 Jun 2008 @ 11:18 PM

  131. Re: 122

    Dear Ray,

    I have seen your posts, and believe me, I certainly appreciate seeing them.

    It is always clear to me that you know what you are talking about.

    That is a quality that somehow always comes through to the reader when the writer is confident of what he/she writes and has a certain ease of writing the science — however briefly.

    This quality cannot be imitated by someone like me.

    But there is one quality that comes through in my writing — and that is my sincerity.

    I hope you will continue.

    Comment by Tenney Naumer — 25 Jun 2008 @ 11:27 PM

  132. Re: #120

    Dear Dr. Pelto,

    Please forgive me for having usurped your post here. I arrived at your post because I am terribly interested in the subject you are presenting.

    I am sure you did take enormous care and time in writing this post. For one thing, you have explained a great deal, and for another, everything you write may be scrutinized by other scientists in your field (that could make anyone take an extreme measure of care).

    As a former technical editor for Elsevier Science Publishers, I know that it is sometimes difficult for authors of academic papers to write down their conclusions. Authors must go a bit beyond the quantitative results. Further, the main conclusion should be included in the abstract, for all to see. It is a bit risky. Scientific reticence can come into play.

    An academic career often requires care and patience and a certain reticence. The tenure-track system can mean 7 years of treading carefully.

    But, in the better departments, a spirit of cooperation is encouraged because it benefits everyone.

    So, I am here asking for help in encouraging the public to realize that there is a broad consensus, and that we must all put our shoulders together in a spirit of cooperation to bring about the necessary changes.

    — lest there be no one left in the future to hit those pubs…

    Comment by Tenney Naumer — 26 Jun 2008 @ 12:05 AM

  133. The latest collapse on May 30 and 31st of the Wilkins Ice Shelf represents the reduction in the width of the ice shelf connection between Latady and Charcot Island from 6 km to 2.7 km. That the connection is being reduced in winter, lends to betting on how long it will take for this connection to be lost and Charcot Island to be surrounded by open water for the first time in a long time. Once again it is the warming of the Antarctic Peninsula area that has led to ice shelf thinning, which primed the pump for structural weaknesses to propogate and the ice shelf to partially fail.

    Comment by Mauri Pelto — 26 Jun 2008 @ 7:53 AM

  134. One issue I have so far never seen discussed is that ice core data and seabed-core data suggests that during the last interglacial – the so-called Eemian interglacial – the temperatures over the Greenland icecover were about 3-6 degrees C higher than now (according to a fresh study by Dahl-Jensen et al. which I heard about on the danish radio), the global mean temperatures probably about 2 degrees higher than now, and the global sea-level about 3-6 meters higher than now (fx. the scandinavian peninsula was an island, the Arctic ocean connected via Arkhangelsk-Ladoga to the Baltic sea to the west of St. Petersburg).;jsessionid=E5A21CD4C92D94619D0C25D50B6C96F3

    But at the same time, the atmospheric CO2-level was only around 290 ppm, so the explanation for the then warmer earth can’t be greenhouse warming?

    I haven’t found any other explanations, but I suppose the Milankovitch cycles, somewhat differing positions of the continents and a somewhat lower Himalaya fx. could be candidates, but still it remains a puzzle “Stage 5 problem
    The stage 5 problem refers to the timing of the penultimate interglacial (in marine isotopic stage 5) which appears to have begun 10 thousand years in advance of the solar forcing hypothesized to have been causing it. This is also referred to as the causality problem.”

    I think the answers to this must be very important in our understanding of the natural climate processes. And still: the polar bears (or their immediate ancestors) seem to have survived this warmer earth, as they survived even the climatic optimum around 9-5000 years B.P. How much sea ice was in the Arctic ocean during the Eem and during the climatic optimum? In Norway, there were pine forests growing 200-400 meters above the present upper limit for forests.

    Comment by Karsten J — 26 Jun 2008 @ 11:23 AM

  135. Re: #130


    You’re preaching to the choir. Trust me, after nearly 35 years of awareness of the issue and nearly 15 years of examining the issue and the last 6 years of dedication to learning the details, I am aware of their arguments. I decided, like you to become involved in helping people understand the argument so we can all make progress.

    If you want to know more about how to deal with the arguments, you might want to read some of my own posts on the matter.

    “Let me tell you something about Joe Q Public.” It is, in my opinion, absolutely necessary that they understand the science, it is necessary for ‘you’ to understand the science.

    If you want to ‘sincerely’ participate in bringing awareness on this issue your success will only increase when you become more aware of the actual arguments and the science that refutes those arguments. Otherwise you will stay in a fight where both sides are throwing air-balls at each other and now learning or awareness is occurring.

    Please learn the science and share it and you will see greater success. Even Kim will eventually start listening to you. It will be obvious to all soon enough.

    I have posted two comments on the Dot Earth blog in the latest article on Hansen. Please stop begging to a crowd that is fully dedicated to the science and the argument. They are doing what they need to do. You need to study the science and get the word out and stop asking others to do work you can do. Sincerity only goes so far.

    There are two arguments: one is political and full of hot air; and one is science and full of observations, facts and modeling. Stick to the science. The more you participate in throwing air-balls the slower awareness happens. You are merely helping the opposition in my opinion.

    Please don’t get me wrong, I am not saying don’t participate. I am saying participate in a more informed fashion. That will help a lot. Don’t be lazy. You can learn this too. It’s not that hard and this is the best site to learn on. You have a lot of passion and yes, sincerity. That can go a long way, but not all the way. Everything you need is right here.


    Comment by John P. Reisman (The Centrist Party) — 26 Jun 2008 @ 11:24 AM

  136. Re #134 Karsten

    I thought the same thing at one point. My thoughts are that it has more to do with the amount of time spent at a particular forcing level. i.e. the longer the system spends at the forcing result of 290ppm the more sea level rise you get. But I am probably oversimplifying.

    Since we are at 1.9 W/m2 now and Co2 has a long atmospheric lifetime, we can expect continued warming and continued sea level rise for quite some time.

    In a complex interaction of systems, it is far to easy to say it “can’t be greenhouse warming” The picture needs to be examined from multiple angles to get a good idea of the drivers and their effects.

    Hopefully, someone more knowledgeable than myself may add to this.

    Comment by John P. Reisman (The Centrist Party) — 26 Jun 2008 @ 12:05 PM

  137. Karsten J Says:
    26 June 2008 at 11:23 AM

    > One issue I have so far never seen discussed is
    > … the so-called Eemian interglacial …

    Karsten, this may help you see those prior discussions:

    Put the word “Eemian” into the Search box at the top of the page, and you’ll be shown all mentions; from that list or by doing more focused searches you’ll find discussion of most if not all of your questions here in prior threads.

    Comment by Hank Roberts — 26 Jun 2008 @ 12:58 PM

  138. Re# 136: Yes, it’s far more complicated than that, I think. Even if the warm Eem earth wasn’t a result of an enhanced greenhouse effect, that doesn’t mean that our present fast global warming isn’t a result of enhanced greenhouse effect either. As I said, the positions of the continents were somewhat different from now, maybe leading to at different regime for the ocean currents (ex. land-bridge between Asia and Australia? Further distance between South America and Antarctica? Small differences can lead to big consequences, when the system passes a threshold). Or (and) maybe the collapse of the Elsterian Ice sheets, which were far bigger than the Weichselian, created a different response involving positive feedbacks leading to the disappearance of the southernmost part of the Greenland ice-sheet and thus a higher sea-level, again propagating higher temperatures in some places, fx. because of the sea around Scandinavia meaning a lesser continental climate there.

    “The warmest millennia of at least the past 250,000 years occurred during the Last Interglaciation, when global ice volumes were similar to or smaller than today and systematic variations in Earth’s orbital parameters aligned to produce a strong positive summer insolation anomaly throughout the Northern Hemisphere. The average insolation during the key summer months (M, J, J) was ca 11% above present across the Northern Hemisphere between 130,000 and 127,000 years ago, with a slightly greater anomaly, 13%, over the Arctic.
    Greater summer insolation, early penultimate deglaciation, and intensification of the North Atlantic Drift, combined to reduce Arctic Ocean sea ice, allow expansion of boreal forest to the Arctic Ocean shore across vast regions, reduce permafrost, and melt almost all glaciers in the Northern Hemisphere. Insolation, amplified by key boundary condition feedbacks, collectively produced Last Interglacial summer temperature anomalies 4–5 1C above present over most Arctic lands, significantly above the average Northern Hemisphere anomaly. The Last Interglaciation demonstrates the strength of positive feedbacks on Arctic warming and provides a potentially conservative analogue for anticipated future greenhouse warming.”

    (“Last Interglacial arctic warmth confirms polar amplification
    of climate change” by Cape Last Interglacial Project Members, january 2006, Quaternary Science Reviews…)

    Comment by Karsten J — 26 Jun 2008 @ 1:35 PM

  139. The high northern latitudes clearly warmer in mid-Holocene a few thousand years ago and during the last interglacial (Eemian) than recently, for orbital reasons (more summer sunshine). Globally averaged harder to call-—still a lot of uncertainties in southern reconstructions. Dahl-Jensen probably cites Cuffey et al. 1995 as some of the first really reliable borehole thermometry for that. The Greenland response to the warmer conditions in summer was retreat behind modern position, poorly constrained (hard to look back under the modern ice sheet to see where it went in the past!), and sea levels 4 to 6 m higher… During the Mid-Holocene, at least one published estimate of perhaps 0.5 m of sea-level equivalent lost from Greenland (given changes occurring in Antarctica and the last remnants of the Laurentide, hard to look at the global sea-level record and see that amount) and perhaps kilometers to tens of kilometers retreat beyond modern position. If you get this much with a bit warmer Greenland, and you’re talking about futures that involve several C to perhaps up towards 10 C for the Greenland vicinity, and with the general physical relation that the warmer it is, the more influential temperature becomes (if you have no melting on top, the ice at the shelf edge, then a bit of warming may do nothing; if you have the ice almost too warm, and warming causes a bit of thinning that lowers the surface and warms more, there is a threshold beyond which the ice sheet cannot survive, so in general the effect of a 1C warming is expected to be larger if the temperature before the warming is higher), you can see why there is concern. Arctic sea ice is also retreating rapidly, with 2007 hitting the record low.

    The skeptics love to say “It was warmer in Greenland in the past” and it was. And the ice sheet responded. Greenland actually doesn’t care who makes it warm or why it is warm, warmer conditions make the ice smaller, and too warm makes the ice go away. If it comforts people to know that Greenland was warmer before and it retreated, and that sea levels were higher, then so be it…

    Comment by Chris Colose — 26 Jun 2008 @ 3:06 PM

  140. Re: #135

    Dear John,

    I think that you must have seen only a very small sample of my comments of Dot Earth because it is well known by the old timers that I almost always back up what I say with the science and links to the research.

    In fact, you can see this by the early comments on Andy’s latest post:

    Lately, because I also have a background in business, I have focused less on the science and more on pension fund managers because public opinion matters very much to them.

    You will be hard pressed to find anyone on Dot Earth, paid denialists included, who doubt my sincerity or my credibility. (N.B. kim is not there to be convinced of anything — kim is there to sow confusion.)

    Have a look at my blog, which I use as a reference since my memory is horrible. Just click on my name — there are over 200 posts of relevant scientific information, graphs, etc.

    I have studied science since I was young child. I have never stopped studying it. This has stood me in good stead as I continue to perform what I consider to be my moral duty.

    I am only one person, living in the middle of nowhere in a developing country, far from research libraries, with no access to online subscriptions to Nature or Science. I just do the best I can. I am not asking anyone to do my work for me, as you put it.

    I do also disagree with you on educating the public. In the last fifty years, we have actually gone backwards on science education — it is not reasonable to suppose that we now have time to educate the general public in climatology. But, we do still have a small window of opportunity during which we must inspire and lead the general public to the conclusion that urgent and strong action is necessary, else we are all lost.

    If scientists who are familiar with climatology do not see themselves as taking part in this process, then what has all the research been for?

    But, I think that I have imposed on the hospitality of realclimate for long enough with this very off-topic discussion. I do thank our hosts for their consideration, and I apologize to Dr. Pelto for going so far off topic.

    p.s. You don’t know me, so I will just let you know that just about everything tickles my funnybone, so I had to chuckle when I read your comment saying that I should not be lazy. Since I began this quest, I have been here at the PC, 7 days a week, from morning until 2 or 3 a.m., reading, writing, posting, learning, communicating, getting up to speed, all unpaid work, to the point that my right arm is fairly useless at the moment, and I have had to become ambidextrous. Somehow, in my mind, that gives me the right to ask people here at realclimate to spend 5 minutes giving a show of public support at Dot Earth.

    Comment by Tenney Naumer — 26 Jun 2008 @ 3:58 PM

  141. Dear Ray,

    I have seen your comments on Dot Earth and they are very important. The more the better.

    Part of my objective is to get the NYT off the fence. Recently, the NYT has shown itself to be quite sensitive to certain criticisms that have appeared in Dot Earth comments. The NYT is hugely influential and can move public opinion. And, we must move public opinion or politicians will not be able to move on the necessary actions to limit CO2 emissions. It is as simple as that, and now is the time, the only time we have left. (I am not a university professor, so I can say that out loud.)

    Comment by Tenney Naumer — 26 Jun 2008 @ 4:14 PM

  142. Karsten J (134, 138) — The Eem was only 125,000 years ago so the positions of all land masses and the height of major mountain chains were essentially the same as now. AFAIK, interglacial 4 was warmer than any of the following three, and of course interglacial 2, the Eem, was warmer than now.

    There is a reconstruction of the Greenland ice sheet during the Eem copied into one of the IPCC AR4 FAQs (I think). It didn’t all melt, just enough so that between GIS and WAIS, the sea highstand was about 5 meters higher than now.

    Despite the so-called 10,000 year problem, which may solely be the result of improper dating of ice cores, there is no reason to suspect anything but orbital forcing and a lot of time: I have a 5766 year segment of the Vostok ice core analysis by Petit et al. centered at the climatic optimum of the Eem. The CO2 concentration starts, in my segment, at 240.4 ppm, rises to 287.1 ppm 3390 years later and then declines to 267.1 ppm at the end of my segment.

    That’s over five millennia, almost six, when melt could have exceeded accumulation at GIS and WAIS. I don’t have any more details.

    Comment by David B. Benson — 26 Jun 2008 @ 4:29 PM

  143. Re: #138 Karsten

    Also, generally and as I’m sure you know, Co2 is typically not the primary climate driver in the natural cycle but a result of the warming in the cycle shift (Milankovitch cycles + plus other effects but likely, mainly the cycles mentioned).

    It is only in this current warming event that Co2 has become a primary driver due to the large scale imbalances imposed on the system of all industrial GHG’s. Co2 is namely a larger culprit due to atmospheric time scale.

    I would love to see the alignment of the eccentricity, obliquity and precession cycles for the last interglacial. That might paint a clearer picture of the extended warm period and associated sea level rise.

    On our current interglacial: with current forcing pushing 2 W/m2 v. the last interglacial which looks to have peaked around .7 W/m2 combined with oceanic thermal inertia lag time and the time scale it takes to absorb the additional forcing.

    Comment by John P. Reisman (The Centrist Party) — 26 Jun 2008 @ 4:57 PM

  144. Anyone interested in Arctic sea ice, check out this MODIS image from today:
    This is the Arctic Ocean, down into the northern parts of the East Siberian Sea and the Chukchi Sea. The pole is roughly on the left-hand edge of this image; the centre is at maybe 80N. All of this sea should be covered with solid ice.
    Look at the character of the ice around the centre of the image.
    Anyone want to bet this ice will still be there in a month?

    Comment by Nick Barnes — 26 Jun 2008 @ 5:48 PM

  145. Karsten,

    The explanation for the 10,000 year lead may lie here:
    Southern Hemisphere and Deep-Sea Warming Led Deglacial Atmospheric CO2 Rise and Tropical Warming There is a 21,000 year Milankovitch cycle which lead to warmer NH then SH summers every 10,000 years. The warm SH starts the deglaciation when the Antartic sea ice retreats, and the Pacific warms giving off more CO2. When the NH warms the CO2 causes the ice sheets to retreat, which releases water vapour and together with more methane causes the ice sheet melting to accelerate. There is also an ice albedo effect. The trigger is the Milankovitch cycle, but CO2, CH4, and albedo all act as amplifiers.


    Cheers, Alastair.

    Comment by Alastair McDonald — 26 Jun 2008 @ 6:44 PM

  146. Re #134 Karsten

    “But at the same time, the atmospheric CO2-level was only around 290 ppm, so the explanation for the then warmer earth can’t be greenhouse warming?

    Your graph shows a rise in CO2 at the beginning of the interglacial from ~200 – 280 ppm that’s a bigger change in forcing (log(CO2)) than from pre-industrial to now. So yes GHE should be part of the explanation.

    Comment by Phil. Felton — 27 Jun 2008 @ 1:59 AM

  147. Tenney,

    I admire what you’re doing, though I don’t understand how you’re supporting yourself while doing it — savings? A pension? A private income? None of my business and I don’t really care what the exact answer is, but I’m glad someone’s doing what you’re doing.

    I’ll try to take a look over there and see what I can add.

    Comment by Barton Paul Levenson — 27 Jun 2008 @ 6:26 AM

  148. Does anyone have a link to the presentation referred to in the article


    Comment by sidd — 27 Jun 2008 @ 10:21 AM

  149. Tenney, I want to ditto Barton’s appreciation for your efforts. I check your site every day and often find useful information.

    Comment by Ron Taylor — 27 Jun 2008 @ 11:16 AM

  150. Re: #148

    That is a sort of “alarming” article.

    Can someone give us info on the state of the WAIS during the last interglacial when sea levels were much higher than they are now?


    Comment by Tenney Naumer — 27 Jun 2008 @ 1:14 PM

  151. Re: #144


    You probably are already aware of this but, the remnants of the multi-year ice have already moved south towards Banks Island and have melted there (or the bit north of Greenland went out past Svalbard).

    This leaves just the saltier and weaker single-year ice, and it is going fast.

    The only thing that is slowing it down, compared to last year, is the change in the PDO that has meant that the water flowing into the Arctic from the Pacific has not been as warm as it was last year.

    Comment by Tenney Naumer — 27 Jun 2008 @ 1:23 PM

  152. Nothing to worry about, just a natural fluctuation:

    No ice at the North Pole
    Polar scientists reveal dramatic new evidence of climate change
    By Steve Connor, Science Editor
    Friday, 27 June 2008

    It seems unthinkable, but for the first time in human history, ice is on course to disappear entirely from the North Pole this year.

    The disappearance of the Arctic sea ice, making it possible to reach the Pole sailing in a boat through open water, would be one of the most dramatic – and worrying – examples of the impact of global warming on the planet. Scientists say the ice at 90 degrees north may well have melted away by the summer.

    “From the viewpoint of science, the North Pole is just another point on the globe, but symbolically it is hugely important. There is supposed to be ice at the North Pole, not open water,” said Mark Serreze of the US National Snow and Ice Data Centre in Colorado.

    If it happens, it raises the prospect of the Arctic nations being able to exploit the valuable oil and mineral deposits below these a bed which have until now been impossible to extract because of the thick sea ice above.

    Seasoned polar scientists believe the chances of a totally ice-free North Pole this summer are greater than 50:50 because the normally thick ice formed over many years at the Pole has been blown away and replaced by huge swathes of thinner ice formed over a single year.

    This one-year ice is highly vulnerable to melting during the summer months and satellite data coming in over recent weeks shows that the rate of melting is faster than last year, when there was an all-time record loss of summer sea ice at the Arctic.

    “The issue is that, for the first time that I am aware of, the North Pole is covered with extensive first-year ice – ice that formed last autumn and winter. I’d say it’s even-odds whether the North Pole melts out,” said Dr Serreze.

    Comment by Jim Galasyn — 27 Jun 2008 @ 2:22 PM

  153. Tenney Naumer @ 151: I saw the pack north of the archipelago was breaking up, in late May/early June (e.g. in fig 5 of the NSIDC update) – that was very disturbing, but I haven’t watched it since then. Can you point us to online images showing it heading west (to the open water by Banks Island) and melting? I’m surprised at your assertion that the ice from north of Ellesmere has moved that far – over a thousand kilometres – in only a month; I thought that drift speeds for the denser ice were generally no more than a few kilometres per day.

    Comment by Nick Barnes — 27 Jun 2008 @ 5:20 PM

  154. Dear Nick,

    There are two different directions of circulation up there, separated by a deep sea ridge (don’t have time right now to look up all the correct names) — one sends the ice out to the Atlantic, and the other (the Beaufort Gyre) towards Banks Island (ice west of Ellesmere).

    I watched the ice begin to crack up in April — very interesting to see the water vapor rise from the fissures. Initially, it moved quite slowly, but gathered speed as the days passed.

    And, well, it is just not that thick, anymore.

    I saved a lot of the satellite images on my harddrive. Give me some time, and I can probably post some on my blog that would demonstrate what happened. I am surprised that no one seems to be talking about it, because it was very easy to observe.

    One of the things that shocked me the most while I was watching was that the point where the ice was thickest (right off the Canadian islands) is exactly where a very long fissure grew, meaning that it sure as hell was gonna go.

    Have a look here:

    But for a really good idea, have a look at the satellite image in this post:

    Comment by Tenney Naumer — 27 Jun 2008 @ 6:23 PM

  155. and in addition to Tenney’s pix, this one shows the old ice pulling away from the islands very clearly.

    The gyre seems to have swung it back again, but if the one-year ice north of it goes then all it will take to push the rest of the old ice away is a few days of winds from the south.

    Comment by Nigel Williams — 27 Jun 2008 @ 6:55 PM

  156. Tenney Naumer (150) — Not in detail, but it is thought that during the Eemian interglacial period that WAIS contributed about half of the 4–6 meter sea highstand compared to now.

    Comment by David B. Benson — 27 Jun 2008 @ 7:07 PM

  157. Re #154

    I mentioned the breakup in the Beaufort sea earlier in the year it has been impressive. The Quikscat movie since September is really impressive as well as the breakup to the west the outflow of multiyear ice through the Fram St is dramatic.

    The rate of ice flow can be seen in the international arctic buoy program, linked to at the foot of that page.

    Comment by Phil. Felton — 27 Jun 2008 @ 7:10 PM

  158. Re: #155

    Nigel, do you have a more recent photo? Thanks

    Comment by Tenney Naumer — 27 Jun 2008 @ 11:00 PM

  159. Re: #147

    Dear Barton,

    I received a partial financial settlement last September which has allowed me to take a ‘leave of absence’ from my regular work. However, it has now been exhausted, and I will need to reduce my current activities. I hope lots of people will take up the slack. I certainly appreciate your comments. Thanks!

    Comment by Tenney Naumer — 27 Jun 2008 @ 11:17 PM

  160. Re: #149

    Dear Ron,

    Thank you so much for your comment. I feel that I am getting behind because so much new research has been coming out in the most recent months — in contrast to when I began back in the fall last year.

    It seems that a critical mass is close to be reached where the denialists will finally be swept away, but the issue should be kept in the public’s mind from now until the next president takes office so that less time will be lost on taking the necessary actions.

    And now, we should let Dr. Pelto have his post back.

    Comment by Tenney Naumer — 27 Jun 2008 @ 11:29 PM

  161. Yes, I saw the coastal polynya grow along the archipelago and thought “well, at least my money with Stoat is safe”. And the weather reports from everywhere around the Arctic Ocean continue to be disturbing (checking just now I can’t find a single place below freezing point; Resolute is at 11C).
    Has anyone heard from Wayne Davison lately?

    Comment by Nick Barnes — 28 Jun 2008 @ 4:47 AM

  162. By the way, the two gyres are the Beaufort gyre and the Barents gyre, and the central motion is the Transpolar Drift.

    Comment by Nick Barnes — 28 Jun 2008 @ 4:51 AM

  163. Re #140

    Dear Tenney,

    I am certainly for all efforts that help get relevant understanding out to the public. As you can see, a lot of people here support your efforts. I don’t agree that we should just ask people to ‘believe’ as that merely gives fuel for the opposing arguments. The better we illustrate the science in context, the faster people will get it right.

    I just thought it was strange that you came in to RC apparently trying to make scientists feel guilty if they did not come over and blog on Dot Earth and basically, albeit lightly, accusing them of not doing enough. If it weren’t for them we would not know what we know now, so I think it is odd to say they are not doing enough.

    Of course you also have pointed out multiple times that you are doing all this for free. Believe me, you are not the only one.

    I’m glad you dedicated the last 8 months to this issue. I’m glad many others have been dedicated to the issue longer than that. I just disagree with the tactics of trying to guilt people into helping you on the Dot Earth blog because you work for free, and coming into RC and saying we are out of time. Everyone knows we are essentially out of time, especially the scientists doing the research on a daily basis. This is probably the last place on earth you need to tell anyone about that.


    I posted several times and the more important posts I made that pointed to the evidence links refuting what some of the posters were saying… well those posts did not show up.

    Andy Revkin wrote me and said that it was a problem in the posting system. But the reality is that those posts still did not get up where they need to be to help people understand.

    The signal to noise problem is real on that blog for multiple reasons. Some are technical.

    Until they fix the problem with posting links to the science it will be very difficult to get people to understand the truth of it all. If you only post a few links you can get a post in. but lists of links that cover a subject appropriately or thoroughly don’t get through. So, mainly it is used for people to spout opinion, which of course can go in circles forever if the facts are not well understood.

    I hope they fix the problem with the links. It is probably a spam bot engine. But for my money, this is the best place to send people still for reference in the debate. At the same time I do my best to interpret what is said and get it out there in understandable chunks.

    Again, I approve of all that are trying to help but I’m saying that better informed opinions will win over lesser informed opinions if presented reasonably, even though it takes time.

    Continued best wishes in your efforts, we really are all in this together,

    PS If you wish to discuss issues and tactics, you can find me on skype just look up my name. I’m always open for communication. Let’s help each other learn about science. You can also reach me through the site.

    Comment by John P. Reisman (The Centrist Party) — 28 Jun 2008 @ 10:32 AM

  164. Dear John,

    The effort needed to save our species will require much more of us than we imagine.

    RealClimate is a wonderful means for scientists to teach and learn from each other.

    It also represents a certain “comfort zone,” and I was seeking to “prod” knowledgeable and respected voices to move beyond it.

    My words, here, cannot make anyone feel guilty unless they already have something to feel guilty about.

    If you wish to post comments with many links at Dot Earth, then you can e-mail your comment to Andy, and he will certainly post it.

    Using tiny urls also works.

    Let me just add that as the non-denialists have improved on Dot Earth, so too have the industry-paid denialists. In the past few days, there have arrived many new and very subtle posters, much more insidious than in the beginning.

    Andy says that there have been more than 200,000 hits per month on that blog; therefore, it is very important to continue efforts to beat down the noise.

    No, I do not receive any monetary recompense for this particular work I am doing, nor would I accept any — I absolutely do not want my motives questioned. But I will tell you anyway what my motive is — I have a daughter, and every instinct in me tells me to do what I am doing in order to do everything in my small sphere of power to secure her future.

    Once again, my apologies to Dr. Pelto for this off-topic comment.

    John, please contact me via my blog if you would like to continue this discussion.

    Thank you.

    Comment by Tenney Naumer — 28 Jun 2008 @ 12:43 PM

  165. The exchanges between Tenney and John, touching on the question of what we can expect from J Q Public, provoke me to remind that there are nearly 7 billion of us. What moves large numbers tends to be mysterious, and there’s room for many approaches, which have many targets, each different, each internally complex, each changing, and each feeding back changes to the others. Seeing how hard it is to know just what to do and say, I tend to be grateful for anyone pushing in what I judge to be the right direction, using whatever time, information, and passion that individual has.

    Comment by Ric Merritt — 28 Jun 2008 @ 3:18 PM

  166. Dear Nick,

    I think we should move over to the North Pole post — saw Wayne Davidson there already.

    Thanks for the info — I have a couple of different maps of the currents that flow in and out of the Arctic Sea, but I do not consider any of them to be very good. I wish I had a more 3D type map to look at.

    Comment by Tenney Naumer — 28 Jun 2008 @ 4:25 PM

  167. Rick,

    The way things are, I have to have a belief in the butterfly effect.

    Comment by Tenney Naumer — 28 Jun 2008 @ 4:26 PM

  168. Here’s an animation of sea ice in the Beaufort Sea from 2008-05-01 to yesterday:

    Created from the asi-n6250-*-v5_nic.png images at

    with these ImageMagick (and bash) commands:

    for f in asi-*20080[56]*; do d="${f:10:4}-${f:14:2}-${f:16:2}"; convert -extract 384x256+448+1024 -repage 384x256+0+0 -font Verdana -pointsize 22 -fill white -draw "text 250,20 '$d'" -type Palette -colors 256 -quality 105 "$f" png8:"$d.png"; done; convert -set delay 50 -delay 200 2008*.png +clone +swap +delete anim.gif

    Comment by Clarence — 29 Jun 2008 @ 12:09 AM

  169. Re: #168


    Thanks! Wow, by the 20th of June, there was only slush moving around and all of the old ice was gone.

    Comment by Tenney Naumer — 29 Jun 2008 @ 8:18 PM

  170. #72 Ken Feldman:

    This is a bit stale by now, but I’ve been wading through the past few weeks’ threads here and the sea level rise discussion caught my eye.

    Chao and Wu recently (2007, AGU) presented data suggesting that for most of the 20th century construction of impoundments considerably delayed/slowed sea level rise. Scrutiny of this work reveals interesting periods during WWII and in the latter years of the 20th century when reservoir construction was either slowed by warfare or, later, by substantial saturation of available reservoir sites. Chao and Wu’s identification of the slackening pace of dam construction in the later part of the last century nicely dovetails w/the observed quickened pace of sea level increase.

    Chao & Wu:

    Comment by Doug Bostrom — 5 Jul 2008 @ 4:32 PM

  171. Antarctic ice shelf ‘hanging by thread’: European scientists

    PARIS (AFP) – New evidence has emerged that a large plate of floating ice shelf attached to Antarctica is breaking up, in a troubling sign of global warming, the European Space Agency (ESA) said on Thursday.

    Images taken by its Envisat remote-sensing satellite show that Wilkins Ice Shelf is “hanging by its last thread” to Charcot Island, one of the plate’s key anchors to the Antarctic peninsula, ESA said in a press release.

    “Since the connection to the island… helps stabilise the ice shelf, it is likely the breakup of the bridge will put the remainder of the ice shelf at risk,” it said.

    Wilkins Ice Shelf had been stable for most of the last century, covering around 16,000 square kilometres (6,000 square miles), or about the size of Northern Ireland, before it began to retreat in the 1990s.

    Since then several large areas have broken away, and two big breakoffs this year left only a narrow ice bridge about 2.7 kilometres (1.7 miles) wide to connect the shelf to Charcot and nearby Latady Island.

    The latest images, taken by Envisat’s radar, say fractures have now opened up in this bridge and adjacent areas of the plate are disintegrating, creating large icebergs.

    Comment by Jim Galasyn — 10 Jul 2008 @ 8:37 PM

  172. Re #171

    Yes Jim here’s a photo:
    That’s a rather skinny connection!

    Comment by Phil. Felton — 10 Jul 2008 @ 8:54 PM


    Comment by Hank Roberts — 18 Jul 2008 @ 12:24 PM

  174. With regard to Alastair McDonald’s Post #110:

    “The question is what will happen when the ice reaches the tipping point at the end of June and the retreat steepens?”

    We are almost at the end of July now. How much worse is 2008 than 2007 in areal ice coverage?

    And on what date this year do you project the North Pole be ice free?



    Comment by jas3 — 21 Jul 2008 @ 1:32 AM

  175. Re #174 I was wrong :-( We didn’t hit a tipping point at the end of June :-), but we seem to have hitting one now at the start of August :-((

    This years Acrtic melt seems to be speeding up …
    … with plenty more in the pipeline, judging by this:

    Cheers, Alastair.

    Comment by Alastair McDonald — 8 Aug 2008 @ 2:34 PM

  176. Re #175 what makes you think there is a tipping point now?

    The NH melt seems to be tracking 2005 and well behind 2007.

    Also, Antarctic ice seems to have swung from a really large positive anomaly to a small negative anomaly. We could just as easily see the opposite in the NH, no?

    Cheers !


    Comment by jas3 — 11 Aug 2008 @ 12:21 PM

  177. My appologies if this is a bit off topic. My daughter and her husband are aboard a 47′ sailing vessel in route from the Falkland Islands to South Georgia. We are trying to locate real time reporting of ice bergs, flow ice, or any significant hazards that might pose significant threats to navigation. Weather data is available via satalite but does not seem to cover ice conditions. Any help would be appreciated.

    Comment by Harsey Leonard — 14 Oct 2008 @ 10:17 AM

Sorry, the comment form is closed at this time.

Close this window.

0.328 Powered by WordPress