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  1. Of course if it is B, as the models might seem to somewhat suggest (and wouldnt be too surprising as just an effect of variability), then no doubt next year the contrarians will start telling everyone how the arctic melt has reversed, in the same way that 1998 has been touted as the ‘end of global warming’ in some corners.

    Comment by stuart — 13 Dec 2007 @ 12:57 PM

  2. This is a little confusing. There’s no need to explain anything particular about September this year. The sea ice was at a record low level before we even got to September. September was more-or-less routine: we lost ice as we do in every September, but not a remarkable amount. The really exceptional time for sea ice loss this year was the second half of June.

    Check the tale of the tape: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg, or the last 12 months: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg

    [Response: Yeah… hmm. The speaker’s statements seemed to make sense to me at the time, but your point now seems like a good one. I could choose excuse A This is not my speciality, I’m only trying to report stuff that seems interesting, or B This meeting is exhausting. Good thing I don’t have to operate any heavy machinery. David]

    Comment by Nick Barnes — 13 Dec 2007 @ 1:05 PM

  3. A recurring problem with public perceptions of excursions in weather and climate is a widespread innumeracy, notably (a) an insufficient appreciation for what it means to have random excursions from a strong trend, and (b) inappropriate assessments of risk, even sizeable ones. The latter really came through in the conclusion of Professor Lonnie Thompson’s talk yesterday. I’ve heard the same from others, that until dead bodies start being carted away from the intersection, noone’s going to think about putting up traffic controls. Unfortunately, here we are talking about numbers of dead much greater than the Shoah, and much greater than the numbers lost in all of World War II. And the powers that are in charge of these things are playing it like a poker game.

    It is just so damn sad.

    Comment by Jan Theodore Galkowski — 13 Dec 2007 @ 1:12 PM

  4. Will the melting of the Ice Sheets have an effect on the orbit of the earth around the sun?

    For that matter does a rising/falling sea level have an effect on the earth’s orbit (5ft-50ft-200ft-tides)?

    Is the suns radiation still increasing over what it was in the past and do the climate models take this into account?

    Comment by paul m — 13 Dec 2007 @ 1:26 PM

  5. Interesting sea ice maps on http://www.arctic-warming.com , when another arctic warming started about 90 years ago.

    Comment by AndrewM — 13 Dec 2007 @ 1:41 PM

  6. paul m,
    Earth’s orbit will not be affected, as Earth’s mass will remain constant. The rate of rotation may be slightly affected as mass shifts from pole toward the Equator and changes (slightly) the moment of Inertia.

    Comment by Ray Ladbury — 13 Dec 2007 @ 2:12 PM

  7. Is there some percentage of ice coverage at which point the ice doesn’t recover much in the winter enough to stop complete melting the next time summer comes around?

    Comment by Brett — 13 Dec 2007 @ 2:34 PM

  8. Paul M asked about the solar trend, assuming it’s going up. Check your assumption for significance, Paul:

    Measured at +0.05 percent (one twentieth of one percent, or five-one-hundredths-of-one-percent — per ten years. Awfully close to zero, eh, compared to the rate of change of fossil fuel use, and temperature.

    >http://www.nasa.gov/centers/goddard/news/topstory/2003/0313irradiance.html

    “The accurate long-term dataset, therefore, shows a significant positive trend (.05 percent per decade) in TSI between the solar minima of solar cycles 21 to 23 (1978 to present). This major finding may help climatologists to distinguish between solar and man-made influences on climate….”

    Comment by Hank Roberts — 13 Dec 2007 @ 3:50 PM

  9. I went golfing one day and started the day by shooting 2 birdies in a row. Well I immediatly extrapolated this to the 18 holes, and concluded that a 54 was in order, due to the results from my limited data set. Unfortunately, I learned the error of my way, and my score returned to the mean.
    The history of the Arctic Ocean, is a blank slate. Any attempt to draw conclusions from the limited amount of data available, is destined to fail. If you can’t tell me what it was like 200, 600, 1000, 4000, 10000, etc. years ago, you can’t tell me where it will be in the future.

    [Response: I rolled a sphere down an inclined plane twice, measured the time it took and calculated the acceleration. I predicted that the for the next 16 rolls the acceleration would be constant. Lo and behold, I was able to predict how long it took the 18th time. See the difference? – gavin]

    Comment by Russell — 13 Dec 2007 @ 4:01 PM

  10. Well, I agree that A and B are correct. “The meltback is permanent” and it “will continue to decrease” at the same rate until it has gone completely!

    Comment by Alastair McDonald — 13 Dec 2007 @ 4:09 PM

  11. It is obvious none of you listened to this presentation at AGU on Monday morning: “PP11A-0203
    Ice free Arctic Ocean, an Early Holocene analogue.”
    Yes, the Arctic Ocean has been ice free many times in the past and that state has lasted many hundreds of years [edit]

    Comment by Dr. J — 13 Dec 2007 @ 4:20 PM

  12. A study relating to this – “Our study confirms many changes seen in upper Arctic Ocean circulation in the 1990s were mostly decadal in nature, rather than trends caused by global warming,” said Morison.

    http://www.nasa.gov/vision/earth/lookingatearth/ipy-20071113.html

    [Response: Note that this has very little to do with the ice melt. – gavin]

    Comment by Gary — 13 Dec 2007 @ 4:33 PM

  13. Paul writes:

    [[Will the melting of the Ice Sheets have an effect on the orbit of the earth around the sun?]]

    Not enough to measure, no.

    [[For that matter does a rising/falling sea level have an effect on the earth’s orbit (5ft-50ft-200ft-tides)?]]

    Again, not enough to measure.

    [[Is the suns radiation still increasing over what it was in the past and do the climate models take this into account?]]

    The Solar constant has shown no trend up or down since about 1950.

    Comment by Barton Paul Levenson — 13 Dec 2007 @ 4:34 PM

  14. Gavin’s response to Russell’s comment about golf is a terrible analogy. I would equate the changing climate to a game of golf long before I would equate it to rolling a ball down an incline. There is very little variability in rolling a ball down an incline. There are innumerable factors that affect climate just as there are in a game of golf. Gavin is suggesting that a linear relationship can be extrapolated out of limited climate data, when it obviously can’t be.

    [Response: No I wasn’t. I was using the analogy of predictability of a system where you have a good idea of the physics vs. an empirical statistical model based on a low number of past occurrences. Physics is extrapolatable, statistics (in this specific case), is not. – gavin]

    Comment by Paul — 13 Dec 2007 @ 4:48 PM

  15. Re 8:

    Go ahead, Gavin, and predict the extent of arctic sea ice for the next 5 years. I hope that sphere you were rolling is crystal, cause you’re gonna need it…

    [Response: I go with option B. – gavin]

    Comment by Patrick M. — 13 Dec 2007 @ 4:56 PM

  16. It is not obvious to me that an ice free north pole is necessarily a positive feedback. The conventional thinking is that the albedo of the ice is much higher than open water, therefore the sunlight will warm the arctic water rather than being reflected back into space. I have never seen the ice free heat exchange condition quantified and compared to the ice cap condition. Please direct me to a reference if handy.

    The upper layer of the ocean is heated by direct sunlight, mostly in the tropics. On average, the ocean surface is warmer than the atmosphere, and that is certainly the case near the north pole. The ocean is cooled by net back (ir) radiation, conduction on contact with the cooler atmosphere, and heat loss due to evaporation.

    So with the ice cap in place, there is no direct solar heating of the arctic water. Without the ice cap, there is only limited solar heating because of the low angle of the sun, 11 degrees above the horizon on average during the six months of sunlight at the pole. At this angle, the albedo of water is about 0.3 or an order of magnitude higher than in the tropics. With the albedo of older snow and ice at about 0.6, the open ocean will absorb more heat than the ice capped ocean.

    With the ice cap in place there is essentially no cooling of the arctic ocean. The ice effectively blocks net back radiation, eliminates contact with the atmosphere and therefore conduction, and blocks evaporation. So the question is, is the small increase in direct solar heating of the arctic water larger than the cooling that occurs when the warm arctic water is left exposed? Qualitatively, it appears obvious that the arctic ocean will net cool. With the sun continuing to heat the ocean water at the tropical latitudes regardless of ice cap conditions up north, it would seem that the presence of an ice cap would result in a warmer ocean over the long term, with the converse also being true. Perhaps this is why there are long term warm/cold climatic cycles, rather than runaway heat or cold. At the peak of each cycle, the oceans are acting counter to temperature trends.

    Comment by B Buckner — 13 Dec 2007 @ 5:25 PM

  17. Re “There is very little variability in rolling a ball down an incline”

    This is true only if you’re measuring in the sorts of units that match our unaided senses – watching the ball roll and counting full seconds to yourself, for example. Use an oscillator to time the ball and you’ll find all sorts of variability, measured in small fractions of a second, in the ball’s travel. The important point is that despite this variability, we can predict adequately well for many purposes, because we understand something about the basic physics. Similar argument for climate…

    Comment by Ian — 13 Dec 2007 @ 5:29 PM

  18. There is hope:
    Arctic Sea Ice Re-Freezing at Record Pace
    After Record Summer Melt, Recovery Still Lags
    http://www.thedailygreen.com/environmental-news/latest/arctic-sea-ice-47121205

    Comment by Mitchell — 13 Dec 2007 @ 5:32 PM

  19. Umm, it seems someone can’t count or I’m missing something. Dispatch #4 is the same as dispatch #3. cheers

    Comment by John Ransley — 13 Dec 2007 @ 5:34 PM

  20. Re 13:

    Option B? That’s lame. Draw a graph of the next 5 years. It’s physics right? It should be similar to predicting an eclipse or rolling a ball down an incline.

    Comment by Patrick M. — 13 Dec 2007 @ 5:34 PM

  21. Isn’t Option B is too easy? If ice of any sort comes back by a sliver for a moment in time, it’s a partial recovery?

    I think the question should be posed in terms of perennial ice, and a recovery should have to exceed 5% to be make it count.

    If slightly more annual ice survives the melt season, is that really significant?

    Comment by J.C.H. — 13 Dec 2007 @ 5:37 PM

  22. RE #3 Paul m’s question about melting glaciers and Ray’s response (#5):”The rate of rotation may be slightly affected as mass shifts from pole toward the Equator and changes (slightly) the moment of Inertia.”

    An interesting point in light of a report several years ago in Science suggesting that the extensive damming of rivers in the northern hemisphere has altered the earth’ moment of intertia, hence, its rotational velocity (increasing it, if I’m not mistaken). Unfortunately, I couldn’t track down the article. But, the following articles do deal with the effects of melting glaciers and rising sea level on the earth’s rotation (not its orbit, of course):

    Global Sea Level and Earth Rotation
    W. R. PELTIER
    Science 13 May 1988:
    Vol. 240. no. 4854, pp. 895 – 9011
    Recent analyses of long time scale secular variations of sea level, based on tide gauge observations, have established that sea level is apparently rising at a globally averaged rate somewhat in excess of 1 millimeter per year. It has been suggested that the nonsteric component of this secular rate might be explicable in terms of ongoing mass loss from the small ice sheets and glaciers of the world. Satellite laser ranging and very long baseline interferometry data may be used to deliver strong constraints on this important scenario because of the information that these systems provide on variations of the length of day and of the position of the rotation pole with respect to the earth’s surface geography. These data demonstrate that the hypothesis of mass loss is plausible if the Barents Sea was covered by a substantial ice sheet at the last maximum of the current ice age 18,000 years ago.

    Oceanic Effects on Earth’s Rotation Rate
    Clark R. Wilson
    Science 11 September 1998:
    Vol. 281. no. 5383, pp. 1623 – 1624

    Changes in the mass distribution of water in Earth’s oceans in turn leads to variations in its angular momentum. In his Perspective, Wilson discusses results presented in the same issue by Marcus et al. in which techniques of radio astronomy were used to measure changes in Earth’s angular momentum. The variations were observed by measuring changes in the length of day, and therefore Earth’s rotation rate. Measurements such as these may serve as an indicator of oceanic behavior, much as other indices are used to keep track of atmospheric climate.

    Comment by Chuck Booth — 13 Dec 2007 @ 6:02 PM

  23. Aren’t a lot of scientific bodies now predicting total loss of Arctic ice during the summer in just a few years? How could that square with even partial recovery of perennial ice? Shouldn’t we expect regular loss of ice every year? Haven’t the models been wildly optimistic about this until quite recently?

    Comment by harkness — 13 Dec 2007 @ 6:10 PM

  24. Sorry, more questions: Is there a possibility that all that fresh water from the melting Arctic ice will find its way into the northern Atlantic, decrease the salinity there, and slow or stall the thermohaline circulation?

    And once the entire Arctic Ocean is ice free, won’t that mean the whole thing will be sucking up solar energy 24/7 during midsummer? Won’t that lead to a super-heated body of water? Will that accelerate the melting of the tundra in Siberia and Alaska, releasing ever more massive volumes of methane?

    Could the Arctic Ocean heat enough in these circumstances to melt the clathrates locked underwater along the continental shelves releasing even more massive amounts of methane? What are we looking at here?

    As I recall from high school chemistry, melting of ice is an endothermic reaction–it cools the water and air around it as it melts. With no more ice melting to cool the water, will we see even higher levels of solar heating?

    Sorry for so many questions, but these have been on my mind for a while.

    Comment by harkness — 13 Dec 2007 @ 6:23 PM

  25. I know my city isn’t the one causing all this American pollution:

    http://www.efficientenergy.org/Top-Ten-Green-Cities-in-the-United-States

    this article shows who is and who isn’t. I also too the carbon calculator at http://www.earthlab.com and I can see that I am not the one who is polluting, you guys should take it too to reaffirm that you aren’t either (I could be preaching to the congregation here)

    Comment by Greg — 13 Dec 2007 @ 6:30 PM

  26. Re “Go ahead, Gavin, and predict the extent of arctic sea ice for the next 5 years. I hope that sphere you were rolling is crystal, cause you’re gonna need it…”

    Well this was from my brother. I am very happy to see it here because he is always elbowing me about how http://www.realclimate.com doesn’t post his comments. So presumably now we will not have to cover that ground any more.

    I have not read the original post yet so I won’t comment further until I have.

    Comment by Andrew — 13 Dec 2007 @ 6:48 PM

  27. Re: “Option B? That’s lame.”

    Did you want the correct answer or to be “impressed” with something false?

    What is YOUR prediction for arctic ice extent over the next five years? If we’re going to call people out for forecasting skill, then by all means let’s have some superior forecasting skill.

    Comment by Andrew — 13 Dec 2007 @ 7:00 PM

  28. Preferential warming at the poles due to CO2 dominance in a dry environment.

    1. It is certainly true that water vapour has a huge and overpowering greenhouse effect.

    2. It is also true that in the polar latitudes there is very little water vapour in the atmosphere. It is mostly locked up as ice or snow or has been simply precipitated out.

    3. Co2 will diffuse throughout the entire atmosphere in accordance with the gas laws.

    4. As the CO2 content at the poles increases it will have the effect of increasing the polar temperatures slightly, particularly during the polar summers. (The effect of Increased CO2 on the tropical latitudes will tend to be swamped by the
    high humidity).

    5.Thus the effect of increasing CO2 since c.1900 will differentially tend to heat the polar regions.

    6. This rise in temperature will allow the water vapour to penetrate further into the polar region before it gets turned into ice

    7. This in turn increases the “greenhouse effect” due to both water vapour and CO2, remember that the effect is circumferential and thus a small linear change is multiplied by piXr2XH(H= atmospheric depth). Presumably there is a vapour diffusion zone centred upon some latitude.

    8. Add in Albedo effects due to ice melt and you possibly have a recipe for rapid change

    This is the sort of feedback mechanism that concerns me.
    Dale Butler

    Comment by Dale Butler — 13 Dec 2007 @ 7:23 PM

  29. The Earth has already experienced a globally averaged 0.7 or 0.8 degree C warming,over the past century, and it may be 3or 4 times that in some regional polar areas.

    Anyone who accepts that sunlight falling on ice free waters which has less reflectivity than sunlight falling on a large ice mass covering those waters and also accepts that this reduction in albedo has a positive feedback effect,leading to further warming, can’t help but opt for A or B, it seems to me.

    The initial warming, over the past century, has caused a condition at the North Pole, that will only add to this warming, which will lead to further melting, which will lead to a further temperature increase. We may well have arrived on the slippery slope as far as the North Polar region is concerned.

    Comment by Lawrence Brown — 13 Dec 2007 @ 7:45 PM

  30. Who has examined the impact of an ice-free summer Arctic and warmer Arctic waters with release of tundra and Siberian ghg sinks? This looks like a place where feedbacks could multiply.

    Comment by Patrick Mazza — 13 Dec 2007 @ 7:50 PM

  31. AndrewM, while your site says past warming in the Arctic was “largely ignored by alarmist scientists”, it has actually been acknowledged by those concerned about the current, ongoing and global trend. Not only on this site, but on NASA’s, where they point out that regional warming through the early 30’s was much slower. Even at this point (and clearly it ain’t done yet), the current trend is broader in scope.

    Comment by Alex J — 13 Dec 2007 @ 7:51 PM

  32. Don’t know a thing about what may or may not be in the IPCC models.
    However, what seems obvious is that it’s not that the freezer is
    completely broken as much as it is that the ice cubes have fallen out.

    In other words, what we are seeing is a dramatically more fluid artic.
    (at least during the summer and fall)
    The increased fluidity is allowing the sea ice to flow out of the artic
    at an unprecedented rate.

    Perhaps some have noticed that the record minimum sea ice extent when
    expressed as a millions-km2 from normal actually occured in October.
    This was well after sun set, but at a time before enough freezing took
    place to lock everthing into place.

    Comment by Andrew — 13 Dec 2007 @ 8:10 PM

  33. The difference in albedo between open ocean and ice/snow in the polar region is small due to the low sun angle. An ice-capped ocean cannot cool because the ice blocks outgoing ir radiation, conductance with the atmosphere and evaporation, all potent cooling effects. Net result, arctic ocean cools without ice cap, warms with it, therefore negative feedback.

    Comment by B Buckner — 13 Dec 2007 @ 9:10 PM

  34. A curious difference between the measurement of loss of ice from the Greenland ice cap and loss of Artic sea ice is the different ways these are measured.

    Greenland ice loss is measured by volume (or equivalently, mass), which makes sense in terms of the implications for sea level rise. Arctic ice loss is measured by loss of area (extent). Yes, sea level rise is not an issue, and ice thickness is difficult to measure.

    Physically arctic sea ice area is important due to it’s influence on albedo, but in terms of melting rate, surely ice volume is more important for the physics?

    I’ve had trouble finding estimates of loss of ice thickness, but it is clear that arctic sea ice has thinned considerably. It is quite possible that we are well past half-way – maybe at 75% in terms of loss of arctic sea ice mass.

    Comment by Bruce Tabor — 13 Dec 2007 @ 9:33 PM

  35. I hope Santa is reading this, because it won’t be long before he’ll be needing a boat. He needs to start cracking now, so rather than his little helpers packing Christmas presents, he needs to be making some long term investments in timber and nails for a sustainable infrastructure……hmmmm, perhaps that’s what we should all be doing. I can imagine some future artist showing Santa careering through the skys in his boat, the sledge being redundent, with the reindeer, now extinct, replaced by dolphins.

    I think your options are a bit vague. Do options “A” and “B” for instance allow even a small recovery?

    What about then option “A”, rapid meltdown of ice until summer free by or before 2013, option “B” no summer ice by 2030, and option “C” summer ice gone by 2080. My option is for “A”, and indeed I think the ice will be gone by 2010.

    We will then have the open Arctic Ocean absorbing, from my understanding, about a third more solar energy each summer due to the difference in albedo between Arctic sea ice and open water. This will dramatically accelerate temperature rises in the northern hemisphere, melt the Greenland ice cap, and for a while we are going to have a planet of two halves – a rapidly warming northern hemisphere and a much more modestly increasing temperature in the southern. I am no climate scientist but what would be the estimate of the maximum difference in temperature rises in the two hemispheres and how long is this state of affairs likely to continue?

    Merry Christmas everone.

    Comment by John Monro — 13 Dec 2007 @ 9:42 PM

  36. RC authors: #4 is link spam from our naval-warfare-caused-warming friend. IMHO it should be removed, but at a minimum the live link should be killed.

    On the general subject of the early 20th century Arctic warming, scientists inspired by Jim Hansen’s ideas had a look and this was the result:

    20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing

    Abstract: Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non–sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.

    To see the full paper, go here and scroll down to the publication list.

    Comment by Steve Bloom — 13 Dec 2007 @ 9:57 PM

  37. John,

    I heard a rumor that “Santa” is firing the elves and moving the operation to a coal-powered factory in China. Say it isn’t so.

    Comment by Alex J — 13 Dec 2007 @ 10:45 PM

  38. John, David reported the choices presented by the speaker, they’re not David’s choices to argue with — David reported what the audience heard and voted on. I was puzzled too, since we know there’s been some refreezing. David, can you clarify what option A meant as presented in the meeting?

    I’d guess that looking at the chart, A might mean what seems to be happening now, if the ice doesn’t recover quite a bit in the next couple of weeks. Comparing the last couple of weeks of December for all the years on the chart record, the line did drop about as low last year and then recover as it dropped the last few days. But look back at where it’s been at the end of December in past years.

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg

    [Response: There wasn’t really any more presented than what I wrote, but I assumed the issue is whether the summer minimum in 2008 will match that of 2007, or whether it would recover somewhat. David]

    Comment by Hank Roberts — 13 Dec 2007 @ 11:23 PM

  39. Bruce Tabor (#31) wrote:

    I’ve had trouble finding estimates of loss of ice thickness, but it is clear that arctic sea ice has thinned considerably. It is quite possible that we are well past half-way – maybe at 75% in terms of loss of arctic sea ice mass.

    The NASA satellite data is coming, apparently. But for a some previews…

    Greenland’s ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer’s end was half what it was just four years ago, according to new NASA satellite data obtained by the Associated Press (AP).

    Arctic Sea Ice Gone in Summer Within Five Years?
    Seth Borenstein in Washington
    Associated Press
    December 12, 2007
    http://news.nationalgeographic.com/news/2007/12/071212-AP-arctic-melt.html

    Comment by Timothy Chase — 13 Dec 2007 @ 11:24 PM

  40. I thought I had seen the year 2013 mentioned somewhere before…

    According to Cryosphere Today, we were below 3 million km sea-ice area on Tuesday, more than 25% below the previous all-time low of 4 million set in 2005. I’d would try and relax: at this rate we have another five years of summer sea-ice. 2013.

    30 August 2007 at 5:14 PM
    Comment 299 of Arctic sea ice watch

    Comment by Timothy Chase — 13 Dec 2007 @ 11:53 PM

  41. Arctic sea ice thickness:

    In 1999 Rothrock et al published a paper showing research from sonar data collected by US Navy submarines that showed arctic ice thickness had declined over large areas of the artic from an average of 3.1 metres to 1.8 metres (about 40%) from 1958-76 to 1993-97.
    http://psc.apl.washington.edu/thinning/thinning.html

    The following site projected the Rothrock data to predict the arctic sea ice would be virtually all gone by this year, 2007.
    http://www.daviesand.com/Choices/Precautionary_Planning/Arctic_Ice/

    Not surprisingly there is evidence that this projection is slightly wrong ;-)

    The following site states German researchers from the Alfred-Wegener-Institute for Polar and Marine Research found that mean ice thickness in September 2007 is 1 metre, down by half from 2001.
    http://news.mongabay.com/2007/0914-sea_ice.html

    I wont pretend this is a thorough literature review, but it suggests to me that ice thickness is more important than ice extent in determining when the arctic will be sea-ice free in summer, and that we have less than a decade until this occurs – it may be as early as September 2012.

    On the plus side, it will be extremely difficult for sceptics to argue against AGW after this “tipping point”. You could always invite them to take an expedition to the north pole by foot, sled, all-terrain vehicle etc.

    Comment by Bruce Tabor — 13 Dec 2007 @ 11:57 PM

  42. If #32, last para., is correct, what effect would a warming northern hemisphere and relatively cooler southern hemisphere have on ocean currents and weather patterns?

    Comment by B. Waterhouse — 14 Dec 2007 @ 12:19 AM

  43. Sea ice coverage in the Antarctic has been larger this summer than last, and shows an opposite trend to the Arctic coverage since the 1970s.

    http://www.gsfc.nasa.gov/topstory/20020820southseaice.html

    If I were a contrarian saying that, I would be answered “you shouldn’t invest your understanding in just one geographical location – you have to see the whole,” but the same criticism can be applied to the post at the top of this thread.

    In the interests of robustness, wouldn’t it be worthwhile acknowledging that qualification and responding to it?

    Comment by barry — 14 Dec 2007 @ 1:09 AM

  44. I’ll put my money on B, but it’s closer to A than you like to admit. The sea ice will continue to accellerate it’s decline until it’s gone- (house of cards scenario) for the short term only during summer, for the medium term until it’s permantly gone, year round. As mentioned by nasa, the apocalyptic ice melt this year preconditions the region for an even more drastic melt the following year (positive feedback at it’s most apparant and stark!) No-one has mentioned the fate of polar bears yet, do we just wash our hands of this species or do we try to relocate as many as possible to sactuaries and zoos?. Canada is a poor option since it will also be largely swamped as sea levels inevitably rise as the greenland melt intensifies. What do you guys think?

    Comment by Lawrence Coleman — 14 Dec 2007 @ 1:35 AM

  45. #40 Barry,
    The point about the Antarctic is that it’s trend is not considered statistically significant.

    Here’s the Arctic – significant.
    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.jpg

    Here’s the Antarctic – not significant.
    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.south.jpg

    Furthermore there are changes in the Arctic that add to the significance – widespread thinning – see below.

    #38 Bruce Tabor,
    I agree. There’s good reason to suppose ice thickness is the major factor.

    1) It takes as much energy to melt an amount of ice as it takes to warm that same amount from 0degC to 80degC.

    2) Thin ice is less mechnically strong than thick. Leads can more easily open in winter allowing ocean to atmosphere heat transfer.

    3) In terms of conductive heat loss through the ice, the thickness is the denominator term.
    i.e. Q = Ki(To-Tf)/h,
    where Ki is a constant, To-Tf is the temperature difference between surface and underside, and crucially the heat flux is Q, h is thickness. So flux is proportional to the inverse of the thickness.

    4) By definition the thicker “perennial” ice takes more than one season to re-grow. So natural variation will have a time-lag on ice growth that does not apply to ice loss. Once thinning has occurred this time-domain asymetricality can “take advantage” of weather events.

    I see sea-ice thickness as a key factor in limiting the impact of summer melt under ice-albedo feedback. A thin sheet of ice will respond all the more quickly in the melt-season thank will a thick. It’s useful to try to qualitatively visualise the differences between the “old” regime as shown in the first link above, and where we seem to be headed.

    Comment by CobblyWorlds — 14 Dec 2007 @ 4:38 AM

  46. We are talking about it being gone in the Summer only as it is not possible for it to be gone in the winter I presume due to the sunless nature of the arctic but I guess that energy from the summer air and water can reduce the extent of sea ice recovery. Is this what we are seeing?

    Due to Antarticas nature of not being surrounded by continents and being a continent its melting potential is different but what is the reality there.

    I know that the arctic is warming quicker than antartica but surely the implications of the antartic warming reach further than the arctics warming due to its continental nature a 2 mile thick ice sheets.

    The bernard convection cells that are expanding at the tropics are down to the arctic shrinking. Is the same true for the southern hemisphere?

    Comment by pete best — 14 Dec 2007 @ 5:28 AM

  47. What is very worrysome here is that arctic sea ice is now being lost faster than thought, and that so little is understood about accelerated glacier flow. Not sure I agree with gavin’s “rolling ball” analogy here. What worries me, in terms of these “tipping points” is that when decadal variability (ex. the positive “natural” AO was mentioned from Morrison) is superimposed on a rising trend in the nonlinear world of sea ice, the system can be pushed across a critical threshold and is unable to return to the initial cyclic state. So if the arctic crosses some point like this, even if we could magically bring conditions back to pre-industrial, the ice may still be like today or worse (and could easily get option “A”). Then you have anthropogenic effects on AO; nearly all scenarios have the AO rising (though not as fast as the ’90s swing).

    Unfortunately, the world of ice is a doom and gloom situation (see Lonnie Thompson’s presentation at AGU). Very alarming, but as Ray Pierrehumbert mentioned in the “latest dispatch” this probably doesn’t mean much when we talk about “tipping point or not” because in any case, there are problems. In either case, emissions need to be lowered.

    Comment by Chris Colose — 14 Dec 2007 @ 5:41 AM

  48. Re. 36 and 37. Timothy Chase.
    Thanks Timothy,
    I can see that my line of thinking has been put before – in the National Geographic article you cite and on Real Climate:
    http://www.realclimate.org/index.php/archives/2007/08/arctic-sea-ice-watch
    I notice (in that thread) Walt Bennett even made the prediction of all permanent arctic sea ice gone in 5 years (2012) and Chris Dillion puts it at 2011. (I posted @38 before seeing your posts.) neither would surprise me, but at this stage I would be surprised if it WASN’T all gone by 2017.

    In line with others’ observations, I suspect the reason we get surprised by sudden reductions in the extent of arctic sea ice is that we don’t have a good handle on what matters – the regional distribution and change in ice thickness.

    Also I loved Chris Gillon’s suggestion for the name of the new geological epoch: the Ohshitocene – my god what have wwe done!

    Comment by Bruce Tabor — 14 Dec 2007 @ 6:05 AM

  49. Re 32,
    “I can imagine some future artist showing Santa careering through the skys in his boat, the sledge being redundent with the reindeer, now extinct, replaced by dolphins.”

    We’ve been doing this for a while where I live in Florida.

    BTW some of us celebrate alternative holidays around this time of year:

    Some call it Squidmas, or Octonoël,
    To some, it’s Kopffüßerweihnachten as well
    In Spain they will wish you “Feliz Nautilidad”
    And think nothing of it–it isn’t that odd.
    There are similar phrases in Greek and Etruscan
    Expressing a good celebration molluscan
    From ocean to ocean, the banner’s unfurled:
    It’s Cephalopodmas all over the world!

    Posted by: Cuttlefish | November 25, 2007 1:15 PM

    http://scienceblogs.com/pharyngula/2007/11/squidmas_is_coming.php

    Comment by Fernando Magyar — 14 Dec 2007 @ 6:45 AM

  50. Sea ice coverage in the Antarctic has been larger this summer than last, and shows an opposite trend to the Arctic coverage since the 1970s.

    http://www.gsfc.nasa.gov/topstory/20020820southseaice.html

    If I were a contrarian saying that, I would be answered “you shouldn’t invest your understanding in just one geographical location – you have to see the whole,”

    Naw, we might point out that the second half of your statement is based on a study published five years ago, and ask why didn’t you say “as of five years ago”, rather than imply that your link shows the trend continues today.

    Comment by dhogaza — 14 Dec 2007 @ 7:02 AM

  51. Re 25

    Check out Gavin’s responses in 8 & 13. Gavin was the one who brought up predictability, not me. Gavin suggested the analogy of rolling a ball down a plane, not me. Gavin gets to draw the graph, not me.

    My opinion is that predicting the climate is NOT a slam dunk. Climatologists are getting better, but they still have a ways to go.

    Comment by Patrick M. — 14 Dec 2007 @ 7:26 AM

  52. Bruce at # 38.

    Afraid the BBC’s motor programme, Top Gear, did just your last point,
    http://www.bbc.co.uk/topgear/show/production_notes/polar_special.shtml

    They raced a 4×4 (SUV) versus husky dogs pulling a sled to the magnetic north pole. Though I’m not sure when they held the race, but I think it was shown on TV a couple of months ago.

    Comment by SP — 14 Dec 2007 @ 7:30 AM

  53. re: #40 (barry)
    This has been discussed often on other threads. If I recall correctly, the decreasing arctic trend is considerably larger than the increasing antarctic trend. The antarctic increase is does not offset the arctic decrease.

    Comment by Kevin Stanley — 14 Dec 2007 @ 9:48 AM

  54. RE # 16

    Mitchell, re-freeze at a rapid pace is not a headline nor is it a sign for hope. Think thickness; not area.

    And, the open water of the far Western top of the Bering Strait appears to be adding heat to Barrows AK.

    See the following:

    13 December, 2007 Global Monitoring Division Hot Items

    Exceptionally Warm Winter Temperatures at Barrow, Alaska Baseline
    Observatory

    Global Monitoring Division – ESRL-GMD
    This story entered on 12th Dec, 2007 09:55:45 AM PST

    The NOAA ESRL Barrow, Alaska, Atmospheric Baseline Observatory located on the most northerly habited point of land in the U.S, has been continuously measuring meteorological parameters since 1977. In November of this year, the average temperature at the observatory was +14.3F (+8C) warmer than the monthly norm. From December 1-10, 2007, the average temperature has been
    +22.2 F (+12.3C) warmer than the long term average for December. These exceptionally warm temperatures are likely due to heat from the warmer Arctic Ocean off shore from Barrow that is still not frozen for this winter.

    The Barrow Observatory chief, Dan Endres, who has been at the Barrow observatory for 23 years, notes that in the 1980s the ocean would generally freeze by the middle of October. In recent years, freeze-up has been
    occurring progressively later.

    Comment by John L. McCormick — 14 Dec 2007 @ 9:49 AM

  55. As NASA has reported, the Arctic ice sheet lost half of its volume since 2004. Given the accelerated rate of meltdown, there seems to be little reason to be believe the ice will survive the 2009 summer.

    I’m interested in knowing whether sea level rise will affect the equator more than the higher and lower latitudes. Once Arctic ice melts off, I would guess that sea level will start rising rather fast.

    Comment by Bill Glenn — 14 Dec 2007 @ 9:50 AM

  56. I’ve also heard that decreased cloud cover played a role in this summer’s melt. Was there any discussion about this at the AGU meeting?

    Also, climate models used to overpredict summer cloudiness I’m not aware if this is still a problem for the more current models.

    Lastly, is there any research on how summer cloudiness in the arctic might change in the future? Or is this something we aren’t able to answer yet, as I suspect?

    Comment by Matthew Janiga — 14 Dec 2007 @ 10:34 AM

  57. Does anyone have a reaction to the sea ice coverage comparisons shown on these images?

    http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh

    Comment by weather tis better... — 14 Dec 2007 @ 10:58 AM

  58. I am selecting option D. It will return to the mean (if we actually know what that is).
    Gavin your analogy needs a little improvement. How about rolling a non-spherical ball down an incline of variable slope, that has snow and patchy ice, and a gusting wind, on a rocking boat.
    The variability of the ice coverage is an unknown quantity, and the current coverage, although outside the norm to our short record, is most likely to be well within the natural pattern of the system.
    Without a coresponding meltdown in Antarctica, there are many situations that can cause the current coverage, and most of them are not indicators of future calamity.
    I will agree that it is a solvable problem. But at today’s understanding it is not. This is multi-variable choas modeling, that exceeds our current ability. So make your prediction, and I will make mine, and 5 years from now we will compare notes. Maybe by then we will be closer to understanding a system that continues to hold more mysteries, than the fiction section at the local library.

    [Response: Sure. My point was not that climate was as simple as a rolling a ball down an inclined plane but simply that physics allows you to make predictions when extrapolations from short time series do not. – gavin]

    Comment by Russell — 14 Dec 2007 @ 11:11 AM

  59. I’ve not found an estimate of how much of last years ice melted within the Arctic Ocean and how much of it left the Arctic Ocean. It looks to me like very favorable conditions for carrying ice out of the Arctic are in the cards.

    Comment by J.C.H. — 14 Dec 2007 @ 11:17 AM

  60. Re #54: [How about rolling a non-spherical ball down an incline of variable slope, that has snow and patchy ice, and a gusting wind, on a rocking boat.]

    Which might be a better analogy for the current state of climate prediction. But I’d have you notice that while it’s hard to predict exactly what path that ball will take on its descent, or exactly when it will reach the bottom, it’s still a pretty darned good bet that it WILL reach the bottom.

    Comment by James — 14 Dec 2007 @ 12:46 PM

  61. Patrick, his point was that predictions made from underlying physics differ significantly from predictions coming purely from statistics. It’s still up to you to understand the nature of the predictions made on the basis of physics and form your questions accordingly.

    More specifically, the study of climate doesn’t involve predicting specific events or conditions. Asking what the underlying physics predicts for a trend is a valid climate question, asking for an exact prediction of next years ice extent is actuly a question about weather. Perhaps you are under the impression that you must be able to predict events specifically to predict an overall trend, but this could not be further from the truth.

    On the topic of Arctic vs Antarctic sea ice, it’s worth point out that the comparison is between summer ice in the Artic and winter Ice in the Antarctic. Winter ice in the Artic is largely bound by the land masses around it, while summer ice in the Antarctica is almost non-existent and therefore also quite stable. Less summer ice in the Artic means lots of sunlight landing on dark water vs reflective ice which can cause further warming. Clearly this isn’t nearly as big an issue for winter ice in the Antarctic.

    Comment by L Miller — 14 Dec 2007 @ 1:18 PM

  62. Re 54:

    Well said.

    If it were easily predictable we wouldn’t need smart people like Gavin spending time on the issue.

    Comment by Patrick M. — 14 Dec 2007 @ 1:21 PM

  63. Well, my reasoning is – if I vote for sea ice it’s gotta come back! ;-)

    Comment by One Brave Soul — 14 Dec 2007 @ 1:28 PM

  64. Re 57:

    I understood Gavin’s point. He picked a very misleading analogy; that was my point.

    I understand the distinction between weather and climate. Granted, 5 years is on the very low end of “climate”, but I don’t think you’ll get many meteorologists claiming that predicting arctic sea ice 5 years into the future is in their ballpark.

    Comment by Patrick M. — 14 Dec 2007 @ 1:39 PM

  65. Yes it will reach the bottom, except under the extreme scenerio, boat rocks at the same time wind blows, and UFO passes over head at low level ;-)
    But that only equates to: The ice volume will be greater in January of 2020, than it will be in July of 2020. I am very willing to go out on that limb. It doesn’t take much bravery.
    Currently we have such a small signal-to-noise ratio, that most people have become frustrated and impatient, and want to call anything that meets a very broad category, a signal.
    If you want to maintain that this is science, and not crystal ball readings, then you have to make sure you can determine the distinction, between the signal and the noise.

    Comment by Russell — 14 Dec 2007 @ 1:42 PM

  66. Re: #48. Do you know the difference between the geographic north pole and the magnetic north pole?

    Comment by Bill — 14 Dec 2007 @ 3:06 PM

  67. barry (#40) wrote:

    Sea ice coverage in the Antarctic has been larger this summer than last, and shows an opposite trend to the Arctic coverage since the 1970s.

    http://www.gsfc.nasa.gov/topstory/20020820southseaice.html

    If I were a contrarian saying that, I would be answered “you shouldn’t invest your understanding in just one geographical location – you have to see the whole,” but the same criticism can be applied to the post at the top of this thread.

    In the interests of robustness, wouldn’t it be worthwhile acknowledging that qualification and responding to it?

    Of course — but then let’s look at the whole.

    Simply as a matter of the distribution of the continents, we do not expect the Antarctic Ocean to behave in quite the same way as the Artic Ocean, not in the short-run. There is more landmass in the Northern Hemisphere, and ocean has more heat capacity than land, land should warm more quickly, therefore the Northern Hemisphere should warm more quickly.

    The Southern Hemisphere sea-ice area broke its previous maximum by 0.9%, the Northern Hemisphere sea-ice area broke its previous minimum by 27%. These really aren’t comparable. Antarctica’s trends are mixed. While there is cooling which been taking place in the continental interior (which is believed to be largely the result of ozone depletion and possible increased snowfall), depending upon the start and end year, much of Antarctica may show either a warming or cooling trend. However, since the beginning of the satellite era, Southern Hemisphere sea ice extent has declined — with most of the decline occuring in the 1960-70s. (See Tamino’s Sea Ice, North and South, Then and Now.)

    We had expected the ice mass of Antarctica to show a slight rising trend for some time simply as the result of projected increased snowfall, but according to Grace gravity measurements, Greenland and now Antarctica are losing ice mass, and satellite imaging shows that weeks of melt have been occuring in recent far into the continental interior of Antarctica as close as 310 miles of the South Pole. Meanwhile, nearly the entire coastline of Antarctica is showing strong warming, not cooling.

    Finally, when dealing with contrarians it might help to remind them every once in a while that heat melts ice. So long as we continue to raise the levels of gases which are opaque to thermal radiation, we can expect the rising trend in temperatures continue. In broad outline at least, the nature of the response from Greenland and the West Antarctic Peninsula will more or less be a given. And with the feedbacks we have been discovering, the response of both is likely to be quite strong.

    Comment by Timothy Chase — 14 Dec 2007 @ 4:13 PM

  68. For those keeping score, the global sea ice anomaly is now positive, granted with all that thin ice.
    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg

    Comment by B Buckner — 14 Dec 2007 @ 4:28 PM

  69. How about coming down the hill at lickety split units of distance per second, and wondering if the driver knows where the cliff is, and if he has a clue where to start stopping to avoid going over the edge. Oh yes, the driver has been known to attempt suicide before. Details about the economics of the situation at the uncertainty principle

    Comment by Eli Rabett — 14 Dec 2007 @ 5:13 PM

  70. Re #64
    I am yet to be convinced that the “end is near”. Your analogy pre-supposes the mountain and the cliff. What if we are just cruising along the interstate in Nebraska, doing the speed limit? Is it approriate to slam on the brakes, just in case there might be a cliff ahead (in Colorado)?
    My understanding indicates the CO2 does not have enough ir thermal radiative capacity to warm the planet to a significant degree, and that the fear is that it will trigger positive feed back warming. So far I am not impressed with the real-world evidence that this is actually occuring. My faith in the models, is also not that strong. I looked through Galvin’s model and I was certainly impressed with all the effort that went it to it. But the reality is he has a rich uncle who is willing to put up with it’s lack of real-world performance. If it was a private sector project, and I had to sell it to a paying customer, it would have to match up with the observed data from the real-world. Tweaking the dials on a model that is grossly over-reaching is an exercise in “GIGO”.
    I view this as an important issue, but it has not crossed the threshold of “the end is near”.

    Comment by Russell — 14 Dec 2007 @ 6:16 PM

  71. Re the golf-versus-bowling-ball comparison in 8:
    isn’t this the difference between stochastic and dynamical systems? The central point is to understand that climate equations are not stochastic, they’re in the realm of continuum dynamics. So they comprise differential equations that we can integrate into the future. The GCMs are essentially Navier-Stokes equations on steroids.

    At least, that’s how I understand Gavin’s comparison.

    Comment by Jim Galasyn — 14 Dec 2007 @ 7:22 PM

  72. More happy news from the cryosphere:

    Climate change blamed as thousands of walruses die in stampedes
    By DAN JOLING
    The Associated Press

    ANCHORAGE, Alaska — In what some scientists see as another alarming consequence of global warming, thousands of Pacific walruses above the Arctic Circle were killed in stampedes earlier this year after the disappearance of sea ice caused them to crowd onto the shoreline in extraordinary numbers.

    The deaths took place during the late summer and fall on the Russian side of the Bering Strait, which separates Alaska from Russia.

    “It was a pretty sobering year — tough on walruses,” said Joel Garlach-Miller, a walrus expert for the U.S. Fish and Wildlife Service.

    Unlike seals, walruses cannot swim indefinitely. The giant, tusked mammals typically clamber onto the sea ice to rest, or haul themselves onto land for just a few weeks at a time.

    But ice disappeared in the Chukchi Sea this year because of warm summer weather, ocean currents and persistent eastern winds, Garlach-Miller said.

    As a result, walruses came ashore earlier and stayed longer, congregating in extremely high numbers, with herds as big as 40,000 at Point Shmidt, a spot that had not been used by walruses as a “haulout” for a century, scientists said. …

    Comment by Jim Galasyn — 14 Dec 2007 @ 7:44 PM

  73. Re Russel’s skepticism of the greenhouse power of CO2 in 65, what do you think is keeping the Earth warm? You do know that without CO2, the planet would be something like 33C cooler…right?

    Comment by Jim Galasyn — 14 Dec 2007 @ 7:49 PM

  74. barry (#40) wrote:

    Sea ice coverage in the Antarctic has been larger this summer than last, and shows an opposite trend to the Arctic coverage since the 1970s.

    http://www.gsfc.nasa.gov/topstory/20020820southseaice.html

    If I were a contrarian saying that, I would be answered “you shouldn’t invest your understanding in just one geographical location – you have to see the whole,” but the same criticism can be applied to the post at the top of this thread.

    In the interests of robustness, wouldn’t it be worthwhile acknowledging that qualification and responding to it?

    Of course — but then let’s look at the whole.

    Simply as a matter of the distribution of the continents, we do not expect the Antarctic Ocean to behave in quite the same way as the Artic Ocean, not in the short-run. There is more landmass in the Northern Hemisphere, and ocean has more heat capacity than land, land should warm more quickly, therefore the Northern Hemisphere should warm more quickly.

    The Southern Hemisphere sea-ice area broke its previous maximum by 0.9%, the Northern Hemisphere sea-ice area broke its previous minimum by 27%. These really aren’t comparable. Antarctica’s trends are mixed. While there is cooling which been taking place in the continental interior (which is believed to be largely the result of ozone depletion and possible increased snowfall), depending upon the start and end year, much of Antarctica may show either a warming or cooling trend. However, since the beginning of the satellite era, Southern Hemisphere sea ice extent has declined — with most of the decline occuring in the 1960-70s. (See Tamino’s Sea Ice, North and South, Then and Now.)

    We had expected the ice mass of Antarctica to show a slight rising trend for some time simply as the result of projected increased snowfall, but according to Grace gravity measurements, Greenland and now Antarctica are losing ice mass, and satellite imaging shows that weeks of melt have been occuring in recent far into the continental interior of Antarctica as close as 310 miles of the South Pole. Meanwhile, nearly the entire coastline of Antarctica is showing strong warming, not cooling.

    Finally, when dealing with contrarians it might help to remind them every once in a while that heat melts ice. So long as we continue to raise the levels of gases which are opaque to thermal radiation, we can expect the rising trend in temperatures continue. In broad outline at least, the nature of the response from Greenland and the West Antarctic Peninsula will more or less be a given. And with the feedbacks we have been discovering, the response of both is likely to be quite strong.

    Comment by Timothy Chase — 14 Dec 2007 @ 8:08 PM

  75. Re: #67 The mother of all GHGs is H20. The rest of GHGs are like planets orbiting the sun. They exist, but are a tiny fraction of the whole. If we don’t have a positive feedback, we don’t have an emergency. We have a very managable situation.

    Comment by Russell — 14 Dec 2007 @ 8:24 PM

  76. Re the old water vapor claim in 68:

    Water vapor is responsible for about 50% of the greenhouse effect, clouds contribute about 25%, and CO2 and other GHGs contribute the rest. Not “a tiny fraction”. You also need to account for the large difference in residence time between H2O and CO2, which is important for dynamics over long time scales.

    Comment by Jim Galasyn — 14 Dec 2007 @ 8:47 PM

  77. Russell, where on earth are you getting your “understanding”? First we have the empirical fact that Earth is warming rapidly–something must be providing the energy driving this warming. If it is not CO2, then what is is. Second, why do you think GCMs have all these adjustable parameters that can be freely tweaked. Most of the forcings are determined independently of the current warming trend, and greenhouse forcing in particular is nailed down to a narrow range by several independent lines of evidence.

    Comment by Ray Ladbury — 14 Dec 2007 @ 10:18 PM

  78. > I assumed the issue is whether the summer minimum in
    > 2008 will match that of 2007, or whether it would
    > recover somewhat. David]

    Thanks, David, that makes sense.

    Heck, we can simplify it — will they have to again add new white space to the anomaly chart, to have room for the line to fit on it, as they did (twice, I think) in the past year.

    Comment by Hank Roberts — 14 Dec 2007 @ 10:30 PM

  79. So far I am not impressed with the real-world evidence that this is actually occuring.

    Here’s a chance for you to educate us, then.

    Please give us an itemized list of the real evidence that warming is occurring, and for each tell us why you find that evidence unimpressive.

    My guess is that your list is going to quite short and is going to reveal just how little you know about the overwhelming evidence that’s accumulating, but this is your chance to prove me wrong.

    Comment by dhogaza — 14 Dec 2007 @ 11:31 PM

  80. 68,69:

    In absolute terms H2O GH forcing is greater than CO2. Unfortunately H2O levels respond very well to temperature increases. If I add a little CO2 (or other forcing) the directly induced warming evapoartes more water, and the H2O forcing increases. This is refered to as a positive feedback -and in this case it operates on a pretty fast time scale ( a couple of weeks ). Some of the other potential positive feedbacks involving methane-hydrate release, or albedo changes due to loss of glacier ice operate on much longer time scales tens to hundreds to thousands of years.

    The real difficulties come with some of the feedbacks that are harder to characterize. Potential changes in cloudiness or cloud albedo. Changes of vegeatation, changes in oceanic and/or atmospheric circulation. My nonprofessional opinion is we haven’t encountered all of the surprises in these areas yet. Didn’t the rapidity of the arctic/subarctic vegetation feedback largely catch the climate community by surprise?

    To what extent might the black carbon become more important if a significant area of the greenland ice sheet becomes an ablation zone (net melting)? Could the BC become concentrated at the surface as older and older ice melts? This is a big effect on mountain glaciers, but these are many times dirtier than polar ice caps.

    Comment by Thomas — 14 Dec 2007 @ 11:47 PM

  81. Re: Gavin 65 I have been very impressed as to the accuracy of the computer models the IPCC researchers have been using..they overall forcast current trends very accurately given a narrow standard deviation for unforseens. The rise in ocean temp is bang on the money, the concentrations of CO2 in the atmosphere has been predicted 10 years ago again by computer modelling and it’s also very accurate. What I have noticed however is that most models are slightly too conservative coz they dont factor in the effects of methane and nitrous oxide, ozone and other lesser but contributing greenhouse gasses. So I happen to have a lot of faith in computer modelling, not just because it’s all we have at this point in time but because their history vindicates their effectiveness in the real world. That’s right russell..GIGO….scientists have always been very fastidious and fanatical NOT to feed garbage into their algorithms.

    Comment by Lawrence Coleman — 15 Dec 2007 @ 4:04 AM

  82. Re Russell #65:

    As someone who has developed models for complex hydrodynamic systems in academia in astrophysics, in national labs on weapons programs, and in the private sector to boot, my $.02 is that you don’t know jack. It is a complete free-market fantasy notion that gov’t funded scientists have models that wouldn’t survive the “real world” of the private-sector, and that somehow having Uncle Sam pay the tab means the quality goes down. Quite the opposite. In my private-sector job, I depend daily on research funded by NASA, NSF, and the NIH, and on models developed by gov’t-funded researchers. That stuff is the best there is. Boeing wouldn’t last a minute without the decades of fundamental aerodynamics research and modeling done by NASA and NACA for the last 60 years. Similar statements could be made about any high-tech industry; take your pick.

    As for your opinions on the models, uhm, what is your background? Got radiative transfer and geophysical hydro nailed down? If not, why should anybody other than you place any value whatsoever on your opinion of the models? If you disagree, hey, follow your free-market muse and start a climate model company. Let me know when the IPO is so I can sell short.

    Comment by Peter Williams — 15 Dec 2007 @ 4:06 AM

  83. If you really want to know how well the private sector makes models, take a look at how companies model their exposure to risk. Now see, free market forces have made these models very reliable and robust, and this keeps the credit system running smoothly, and…. oh, wait.

    Comment by Peter Williams — 15 Dec 2007 @ 4:27 AM

  84. First of all, I didn’t mean to sound shrill in my last posts. I had a bad afternoon, and I didn’t have a proper outlet, so I vented a bit of frustration on the blog, that I should have re-directed to thermal radiation of the troposphere.
    I don’t have time to go into a line-by-line discussion of this issue, right now, but I will give you a chance to get your jabs in, soon.

    Comment by Russell — 15 Dec 2007 @ 4:56 AM

  85. Russell writes:

    [[My understanding indicates the CO2 does not have enough ir thermal radiative capacity to warm the planet to a significant degree,]]

    That’s kind of a meaningless statement. What is “thermal radiative capacity?”

    [[…So far I am not impressed with the real-world evidence that this is actually occuring.]]

    That one quote says it all, I think.

    Comment by Barton Paul Levenson — 15 Dec 2007 @ 7:18 AM

  86. Russell writes:

    [[Re: #67 The mother of all GHGs is H20. The rest of GHGs are like planets orbiting the sun. They exist, but are a tiny fraction of the whole. If we don’t have a positive feedback, we don’t have an emergency. We have a very managable situation.]]

    According to Kiehl and Trenberth’s 1997 energy budget for the Earth-atmosphere system, water vapor causes 60% of the clear-sky greenhouse warming and carbon dioxide causes 26%. Also, the water-vapor feedback is indeed a “positive feedback,” so by your own definition, we have an emergency.

    Comment by Barton Paul Levenson — 15 Dec 2007 @ 7:20 AM

  87. Ref 71 dhogaza writes “Please give us an itemized list of the real evidence that warming is occurring, and for each tell us why you find that evidence unimpressive.” Surely you have got this wrong. What we should be discussing is all the things that show that while the earth’s temperature did increase at the end of the 20th century, temperatures have now stabilized, and the earth is now starting to cool. Such things as the fabulous ski season there was in the southern hemisphere in 2007, followed by an equally impressive one now occurring in the northern hemisphere. The killing frost there was in Argentina on November 14th 2007, which destroyed millions of dollars worth of crops. The enormous freeze of arctic sea ice that occurred in November 2007. The RSU MSS satellite data that shows the earth’s temperature had a negative anomaly in November 2007; the first negative this century. Do you want me to go on?

    Comment by Jim Cripwell — 15 Dec 2007 @ 7:23 AM

  88. Hank Roberts@71: yes, they grew the chart twice in 2007, once from -2 to -2.5, once from -2.5 to -3. I think that the second time they grew the topside as well, for symmetry; at the start of the year it ran from -2 to +2.

    Comment by Nick Barnes — 15 Dec 2007 @ 8:12 AM

  89. The total world primary energy production in 2003 was 4.4 × 10^20 Joules, which was sufficient to melt 1.3 × 10^3 Gigatons of ice, where 1 Gt = 10^9 metric tons. This figure is about twice the estimated amount of ice actually melted.

    Comment by AEBanner — 15 Dec 2007 @ 9:26 AM

  90. > Do you want me to go on?
    Jim Cripwell, Gavin already told you he didn’t want you to go on.
    So stop.

    Comment by Hank Roberts — 15 Dec 2007 @ 11:05 AM

  91. Re #80: [Such things as the fabulous ski season there was in the southern hemisphere in 2007, followed by an equally impressive one now occurring in the northern hemisphere.]

    Did you forget the sarcasm button? Fabulous ski season in the northern hemisphere? Not in these parts (the SIerra Nevada). The downhill areas that have opened are running mostly on manmade snow. Didn’t get any significant natural snow until the beginning of this month, and only about a foot so far – conditions more typical of late October/early November.

    Comment by James — 15 Dec 2007 @ 11:58 AM

  92. Re Jim’s “good news” in 80:

    Then there was all that great rainfall in Australia this year that stopped the worst drought in a century… oh wait.

    Comment by Jim Galasyn — 15 Dec 2007 @ 12:01 PM

  93. Jim, (#80)

    I also note that the Dow has risen 10 out of the last 21 trading days, and US GDP is at an all-time high. So clearly we can extrapolate that it would be alarmist to speak of a looming risk of a recession, right? Do you want me to go on? Ever hear of cherry-picking? It’s what people do when they’re trying to sell you something, or what they do on talk radio when they want you to feel the delight of righteous indignation. Hardly scientific. Besides, you didn’t even explain why your laundry list was evidence of cooling. Without a framework of understanding, it’s not clear what those isolated events indicate. Why is a very fast refreeze of Arctic ice evidence of cooling? I’m not remotely an expert on that, but gee, seems kind of what you might expect, given the radiative efficiency of open water. If I really wanted to know, I’d ask an expert, not someone with a list of talking points.

    Besides, the ski season in the Sierras is lousy so far, so you’re doing cherry-picking upon cherry-picking. Don’t quit the day job.

    Comment by Peter Williams — 15 Dec 2007 @ 12:39 PM

  94. #65 Russell:

    If it was a private sector project, and I had to sell it to a paying customer, it would have to match up with the observed data from the real-world.

    If it was a private-sector project, it would likely come without source code, and of course it would match up beautifully with past observations ;-)

    Comment by Martin Vermeer — 15 Dec 2007 @ 1:09 PM

  95. “No-one has mentioned the fate of polar bears yet, do we just wash our hands of this species or do we try to relocate as many as possible to sactuaries and zoos?. Canada is a poor option since it will also be largely swamped as sea levels inevitably rise as the greenland melt intensifies. What do you guys think?”

    At this point, the sea ice in contact with the northern part of Ellesmere Island and the northern part of Greenland is still there year round. The polar bears in the western Hudson bay seem to do fine with the abscense of sea ice for 3 to 4 month a year. It would take quite a bit more warming to achive an abscense of sea ice at the northern part of Ellesmere and Greenland for 3 to 4 month a year. And until that occures there is probably no danger of polar bear extinction.

    Speaking of Ellesmere Island, there are fossilized forrests on the island. This would tend to indicate much warmer weather there in the past. Probably warm enough to produce ice free summers at the pole. How did the polar bear survive such a time.

    [Response: They didn’t. The Ellesmere forests are from the Eocene (50 million years ago). – gavin]

    Concerning the discussion of the tipping point and the heating effect due to loss of albedo, the question I have is, how did we then get back to ice ages in the past, when all of the polar ice was melted and there was no ice caused albedo. Shouldn’t the earth have continued to stay too hot to allow ice ages to return under that scenario?

    Comment by Tilo Reber — 15 Dec 2007 @ 2:39 PM

  96. Jim Cripwell, you’re saying that one negative temp anomaly in 7 years is proof that the Earth is cooling. That’s grotesque. It seems that you have a serious double standard on burden of evidence. Imagine all the things I could say on GW and AGW if I allowed myself to make such a jump to conclusion. Gee, the possibilities…

    Comment by Philippe Chantreau — 15 Dec 2007 @ 3:48 PM

  97. Tilo Reber@87: “It would take quite a bit more warming to achive an abscense of sea ice at the northern part of Ellesmere and Greenland for 3 to 4 month a year. And until that occures there is probably no danger of polar bear extinction.”

    This is exactly what the arctic sea ice specialists are talking about. What else do you suppose they mean when they say “an ice-free arctic summer”? Which they predict for, variously, 2040, 2035, 2030, 2025, 2017, ….

    And the models say that once the summer ice is gone, it’s not easy to bring it back. The heat that could melt a single metre of sea ice (e.g. first-year ice) can heat (say) the top 40 metres of open ocean by 2 degrees C.

    The polar bears are in serious jeopardy. There are presumably some areas of fast ice, e.g. on the coastal areas which you mention, especially the northern coast of Greenland – cooled by the ice sheet – which might work as natural refuges.

    While I’m here, can I encourage anyone wittering about the rapid November regain in sea ice firstly to notice that this was predicted by the experts and secondly to take a look at the chart.

    Comment by Nick Barnes — 15 Dec 2007 @ 4:22 PM

  98. Re 34: STOP PRESS:
    A most recent and reliable information, although not yet corroborated by independent sources, is that Mr. Santa will be mothballing his multiple North-European industrial operations due to the dismal near term forecasts of snow availability. This will, of course, be a great loss to the regional economies.

    He is reported to be negotiating a transfer of the Swiss/French treaty covering the CERN facilities. These extensive cave labyrinths will be on the market in the near future as the elusive Higgs boson will soon be trapped. Their proposed major project of actually demonstrating the Big Bang has now definitely been rejected for EU Framework Program funding.

    The CERN facilities are ideal for political reasons. Santa’s famed Earth Rotation Switch (ERS) has to be guarded at all costs against any and all prospects of weaponizing. As has been known for some time, the ERS allows its possessor to perform quite impossible feats of global delivery – although with some undesirable side-effects. For instance, it actually has been observed to turn minutes into hours during some evenings, after the sunset.

    The new facility will be powered by a New Sahara Solar Corporation plant to be located nearby.

    The plan is reportedly backed by serious money from the usual suspects in Shanghai. We are formally assured by our confidential sources that the trademark photo opportunity “Me, on the knee of Santa” will continue to be available to the millions, but without the current airport congestion problem.

    Season’s Greetings!

    Pekka

    Comment by Pekka K. — 15 Dec 2007 @ 5:11 PM

  99. Re # 87 Tilo Reber’s question about polar bears on once-forested Ellesmere Island and Gavin’s response:

    Had polar bears existed when Ellesmere Island was forested, they probably would have been eaten by the carnivorous dinosaurs that lived in that region:

    http://www.athropolis.com/arctic-facts/fact-dinosaur.htm

    Comment by Chuck Booth — 15 Dec 2007 @ 5:23 PM

  100. “They didn’t. The Ellesmere forests are from the Eocene (50 million years ago).”

    Good point Gavin. So let’s bring the time in some. How did the polar bears cope during the Holcene optimum? If the temperatures were higher than today, then can we also assume that the Arctic sea ice melted in the summer? I seem to remember hearing that there was a period of time when the Atlantic and Pacific bowhead whales could visit each other in the Arctic.

    Comment by Tilo Reber — 15 Dec 2007 @ 5:49 PM

  101. I have a couple of temperature charts that I would like you all to verify. One is an RSS temperature anomaly chart and the other a HadCRUT3 temperature anomaly chart. These would seem to be very important, but I don’t know if I can trust them, considering their source.

    http://www.junkscience.com/MSU_Temps/RSSglobe.html
    http://www.junkscience.com/MSU_Temps/HadCRUG.html

    If these can be verified, then it seems that we are in the same place – temperature anomaly wise – in Dec of 07 as we were in Dec of 79. How would that be possible with CO2 having gone from 340 PPM to 380 PPM and with the Arctic albedo having significantly decreased?

    Thanks for any information.

    Comment by Tilo Reber — 15 Dec 2007 @ 11:19 PM

  102. #80

    You’re kidding, right? That’s the sort of pop science thinking plaguing the White House and congress, members of whom don’t appear to understand grade school science.

    As an aside, I’ll second the new epoch, ‘ohshitocene’. My eleven year old son nearly choked laughing…until he remembered that it was the epoch in which he’d be growing up.

    Comment by Sonny — 16 Dec 2007 @ 5:48 AM

  103. “You’re kidding, right? That’s the sort of pop science thinking plaguing the White House and congress, members of whom don’t appear to understand grade school science.”

    Thank you Sonny. I don’t mind the personal attack. But it would have been nice if you had answered my questions as well.

    Comment by Tilo Reber — 16 Dec 2007 @ 11:44 AM

  104. Re #87: [Speaking of Ellesmere Island, there are fossilized forrests on the island. This would tend to indicate much warmer weather there in the past.]

    Or perhaps, given that it was 50 million years ago, that Ellesmere Island was located somewhat further to the south?

    Continents do move around, you know. In connection with which, we might consider the formation of the Central American land bridge, which separated the Atlantic & Pacific oceans. It’s interesting to note that this happened only about 3 million years ago, IIRC about the same time that the current cycle of ice ages kicked off. Maybe some cause & effect?

    Comment by James — 16 Dec 2007 @ 12:41 PM

  105. f these can be verified, then it seems that we are in the same place – temperature anomaly wise – in Dec of 07 as we were in Dec of 79. How would that be possible with CO2 having gone from 340 PPM to 380 PPM…

    You can’t just compare two points as you seem to be doing with the RSS data, at least.

    Ask yourself: why has the junkmeister failed to plot a trend line on that graph?

    … and with the Arctic albedo having significantly decreased?

    Um, in December the Arctic is dark 24 hours a day, why would its albedo have any effect during this month?

    Comment by dhogaza — 16 Dec 2007 @ 1:30 PM

  106. Re: 89

    Draw a straight line through their graphs, and you see undeniable warming surrounded by random noise (and a few unpredictable, yet significant factors such as El Nino and Volcanoes). The anomaly at any given moment depends on any number of things. We’ve seen warming of 0.4 to 0.5 degrees over the satellite era, which is just about the same as the magnitude of the noise from year to year. So you can take “cold” months from the last few years, and compare them to “warm” months 30 years ago, and then conclude that “there is no warming.” That is Cherry-Picking in the extreme.

    These is the temperature anomalies for GISS (instruments), Hadley (instruments), UAH (satellites), and RSS (satellites) since the beginning of the satellite era. The X axis is “months since Jan 1979.” The anomalies have been shifted upwards or downwards to give each trend a y intercept of 0.

    http://cce.000webhost.org/giss.jpg
    http://cce.000webhost.org/hadcrutv.jpg
    http://cce.000webhost.org/uah.jpg
    http://cce.000webhost.org/rss.jpg

    Tamino has a few posts on this subject:
    http://tamino.wordpress.com/2007/12/16/wiggles/
    http://tamino.wordpress.com/2007/08/31/garbage-is-forever/
    http://tamino.wordpress.com/2007/10/16/many-factors/

    Comment by cce — 16 Dec 2007 @ 2:28 PM

  107. Re #89

    Tilo read this: http://tamino.wordpress.com/2007/12/16/wiggles/

    Comment by Phil. Felton — 16 Dec 2007 @ 2:31 PM

  108. Polar bears may be the most visible potential victims of an ice-free actic, but the entire ecosystem may be in peril. Turns out that “Ice algae are a very important part of the marine food web, contributing on average 57% to the total Arctic marine primary production.”Krembs & Deming

    Worst case both the pelagic and benthic arctic ecosystems could collapse. So walrus, seals, and the acrtic cod are endangered.

    Tipping points indeed. Why, exactly, did we bother to save the baby harp seals?

    Tim

    Comment by Tim McDermott — 16 Dec 2007 @ 4:47 PM

  109. Just this last week December 13, 2007 RUSH Limbaugh bravely announced that artic ice coverage was recovering at a record rate. Well that IS a load off! (sarcasm) I can’t wait to find out what the man thinks about peak oil.

    Patrick

    Comment by Patrick Roche — 17 Dec 2007 @ 9:33 AM

  110. As another piece of the 2007 Arctic sea ice puzzle, my group at Colorado State just submitted a paper to GRL on the 2007 ice anomaly. We found that 2007 was quite anomalous in terms of cloud cover over parts of the Arctic, especially the western Arctic where much of the ice anomaly occurred. Amazingly, Fox covered the story at AGU – you can read about it here:
    http://www.foxnews.com/story/0,2933,316753,00.html

    The paper will not appear for a while, but the gist is that cloud cover in 2007, especially June and July, was 10-15% lower in the western Arctic, and this coupled with the especially thin sea ice probably played an important role in the massive ice melt. The extra sunshine was enough to melt roughly 0.3 m of ice directly, or warm the surrounding oceans by about 2.4 K.

    Comment by Chris O\\\'Dell — 17 Dec 2007 @ 11:05 AM

  111. Re #106
    Since AGW is contagious through-out our solar system, Mars should be melting its ice-cap any day now. That will release CO2 and water vapor, and all kinds of nasty GHG’s into the atmosphere. It will reach the tipping point, and make the planet habitable.
    It could be the perfect refuge for polar bears, walrus, and all manner of cold weather critters.

    Comment by Russell — 17 Dec 2007 @ 12:10 PM

  112. Any idea what has gone wrong with the charts over at Cryosphere Today?

    Comment by Nick Barnes — 17 Dec 2007 @ 12:29 PM

  113. I will no longer be commenting on this blog as I’ve begun work on my first novel. It’s called “The Sea Ice Also Refreezes.”

    Comment by J.C.H. — 17 Dec 2007 @ 1:26 PM

  114. Tim, thank you very much for this link, it’s answered a lot of questions I’ve had about how and when and where in the sea ice the algae grows. And _that_ answers what changes in the absence of sea ice. Repeating it:
    http://www.arctic.noaa.gov/essay_krembsdeming.html

    This is part of “primary productivity” — scary to see changes at this basic level.

    Comment by Hank Roberts — 17 Dec 2007 @ 1:41 PM

  115. Re #111, Uh, Russell, do you have even a vague notion of what drives climate on Earth, let alone on the other planets? Venus is dominated by a runaway greenhouse effect. On Earth insolation and greenhouse gases are important. On Mars, insolatin and dust storms are the main drivers. By the time you get to Jupiter, insolation is less important–Jupiter gives off more energy than it receives from the Sun. Maybe you should listen to Mr. Twain: “What gets us into trouble is not what we don’t know. It’s what we know for sure that just ain’t so.”

    Comment by Ray Ladbury — 17 Dec 2007 @ 2:14 PM

  116. Re #110: Chris, the decreased cloud cover had been mentioned as a major factor at the time of the minimum. I’ll look forward to reading the paper to see the details, but does it include (or do you have) any thoughts as to why there was such a large reduction or whether there’s any reason to expect more of the same in the near future? Also, I believe Maslowski’s results don’t assume a major trend in cloud cover (or at least that wasn’t mentioned in the abstract or press coverage), so I’d appreciate knowing your view as to what can be expected if cloud cover recovers.

    Comment by Steve Bloom — 17 Dec 2007 @ 4:11 PM

  117. re: #110. Chris, does this mean Arctic heat transfer processes are dominated by the direct radiative process and less so by convective heat transfer between the ice and the atmosphere? It would seem that during the long Arctic Winter radiative cooling dominates over convection from the tropics as ice is added during this period.

    How do the structural-dynamics causing breakup, and thus increasing the surface area-to-volume ratio between the liquid water and the solid ice, fit in? The surface area to volume ratio between the ice and the atmosphere also increases, but 90% of the ice is under water.

    In general I’m asking what are the dominant structural, hydrodynamic, and energy-balance related (radiative and convective heat transfer, for both the atmospheric and the ocean) phenomena and processes that govern the decreases and increases in Arctic ice volume?

    Thanks

    Comment by Dan Hughes — 17 Dec 2007 @ 4:51 PM

  118. Re #116 – Steve, we really do not know the ultimate reason for the decreased cloud cover this year. There was anomalously high Arctic SLP this year – so it could be related to the phase of the NOA or AO, but we’re really not sure at this point. We only conclude that thinner sea ice in the future will be more vulnerable to the variability in cloud cover. It could very well be that there is a feedback loop between sea ice and cloud cover, but that remains an open question and is beyond the scope of our paper. By the way, a rough time series of June+July cloud cover over the western Arctic from MODIS-Terra data for 2000-2007 is
    2000: .54
    2001: .65
    2002: .57
    2003: .63
    2004: .52
    2005: .46
    2006: .58
    2007: .40
    (70+ N latitude, 120-180W longitude)
    So you can see that 2007 was quite anomalous, but so was 2005 (which also had a very low ice amount). -Chris

    Comment by Chris O\'Dell — 17 Dec 2007 @ 5:00 PM

  119. Re #117. Dan, I think I’ll have to defer this question to an expert on Arctic sea-ice modeling, which I am unfortunately not. I am more of an expert in the remote sensing of cloud properties using satellite instruments, which is my connection to the paper I referred to. I can only speculate that all the processes you mentioned are important, and that probably their relative level of importance changes from the arctic winter to the arctic summer. Certainly direct radiative processes are very important in both summer and winter, but then again I would guess that so are vertical (ocean-atmosphere) and horizontal (ocean-ocean) convective processes. -Chris

    Comment by Chris O'Dell — 17 Dec 2007 @ 5:14 PM

  120. Who’s going to the Orlando meeting on the oceans and climate? March 2-7
    http://www.sgmeet.com/aslo/orlando2008/allsessions.asp

    Comment by Hank Roberts — 17 Dec 2007 @ 5:18 PM

  121. 552 billion tons of ice melted this summer from the Greenland ice sheet, according to preliminary satellite data to be released by NASA Wednesday. That’s 15 percent more than the annual average summer melt, beating 2005’s record.
    By SETH BORENSTEIN (quoting f.i. abdalati and serreze NSIDC)– 5 days ago / associated press
    Can anyone confirm this? Is this 552 km3 for real? That would be a pretty awkward melt-explosion.

    Comment by Hans Vermeer — 17 Dec 2007 @ 6:04 PM

  122. re #104 “Or perhaps, given that it was 50 million years ago, that Ellesmere Island was located somewhat further to the south?”

    James, this is from a link that Gavin was kind enough to provide.

    “Paleolatitude studies suggest that the forest lay close to its present high-latitude position during the Eocene.”

    Comment by Tilo Reber — 17 Dec 2007 @ 6:32 PM

  123. re #108 “Turns out that “Ice algae are a very important part of the marine food web, contributing on average 57% to the total Arctic marine primary production.””

    Tim, it’s fascinating that there is enough energy inside the ice to allow these creatures to thrive. One thing did catch my eye in the article.

    “it provides a habitat for photosynthetic algae and nursery ground for invertebrates and fish during times when the water column does not support phytoplankton growth;”

    If the ice melted and the water was warmer, then would phytoplankton growth be supported? And would phytoplankton be a replacement microscopic food source? In Hudson bay, where it is melted 3 to 4 month a year, what is the microscopic food source that supports the food chain all the way up to seals and polar bears?

    Comment by Tilo Reber — 17 Dec 2007 @ 6:40 PM

  124. Re #107

    Phil – thanks I read the article. It was very informative. It also brought up some questions. Let me try them out on you.

    1. How do you select a timescale to determine if a trend is significant? Let’s say we throw out the El Nino year of 1998. Then we are saying that the slope established in the 22 years from 1975 to 1997 is significant, but the slope established in the 8 years from 1999 to 2007 is not. Somehow that doesn’t have a good intuitive feel to it.

    2. Let’s say that I accept that the slope from 1999 to 2007 is noise. Then comparing our current temperature chart to the hypothetical one created at your site, it would look like we are now at the very edge of the noise band. In fact, one might argue that the RSS data puts us over the band. This means that the temperature will have to start back up very soon or we will be out of the band and the data will become signal rather than noise. Guess we’ll have to do a wait and see for that one.

    3. The modeling experiment that we are talking about only tells us that the noise bands are just wide enough so that the temperatures that we have seen for the last 8 years could be noise. It doesn’t tell us that they are noise. That will be decided by the data that comes out in the next 2 to 3 years.

    4. I have a bit of a problem regarding anything in nature as noise in the same way that we generate computer noise. I don’t think that there is such a thing as noise in nature. We may identify major forcing trends and say that they represent the long term trend. And we may say that the noise represents a large number of minor and possibly unidentified forcing factors. But when you say that a forcing factor is and will remain the major forcing factor when you only have 22 years of data, and when the other forcing factors are neutalizing your dominant factor, even for 8 years, I think that is saying too much.

    5. The other thing that I wonder about is the modelers desire to use a 0.018 deg.C/yr CO2 forcing factor. And let’s say I accept that. But CO2 forcing is not linear. Supposedly the frequency band that CO2 is good at absorbing is already mostly absorbed by the current level of CO2. So more and more CO2 gives us less and less forcing. Can we know that there is enough residual forcing in CO2 to maintain a 0.018 deg.C/yr slope for any significant number of years?

    Comment by Tilo Reber — 17 Dec 2007 @ 7:43 PM

  125. Re #121

    552 km^2 is nothing compared with the additional 1.5 million km^2 of sea-ice that melted in the arctic in excess of the previous record.

    Comment by Phil. Felton — 17 Dec 2007 @ 9:17 PM

  126. Re #118: Thanks for the response, Chris. What’s most interesting is 2006 since it would have been another record low had it not been for an August cold snap (see NSIDC’s 2006 season report here). So perhaps Maslowski is right that it’s the warm water intrusion.

    Comment by Steve Bloom — 17 Dec 2007 @ 11:34 PM

  127. In Hudson bay, where it is melted 3 to 4 month a year, what is the microscopic food source that supports the food chain all the way up to seals and polar bears?

    The polar bears are on land, and eat very little if at all, during those months. Then when it freezes, off they go. Mmmmmm, fat juicy seal, smack-smack, chew-chew, tastes good after not eating for so long!

    Those who claim that polar bears will easily adapt to a more terrestrial lifestyle seem unaware that they’ve lost the habit (and perhaps the physiological adaptations, though I’m not sure) of foraging for food on land. Our other two bear species exist to a large extent on tubers and berries, meat forming a lesser portion of their diet. Much like people, which is one reason they love our garbage cans so much. We eat food that black bears and griz love.

    Polar bears are devoted to meat, fresh meat.

    Comment by dhogaza — 18 Dec 2007 @ 4:08 AM

  128. The warm water coming from the Bering Sea, I think?

    “The climate and ecosystem of the Bering Sea has changed over the previous fifty years. There are two shifts in climate associated with increased warm temperatures and other factors, the first in the late 1970s and again around 2000. There was a major ecosystem reorganization following the late-1970s shift. These changes represent a transition from primarily cold Arctic ecosystems earlier in the 20th century, dominated by sea ice, to sub-Arctic conditions…. a shift toward warmer temperature of 2 deg C around 2000. Of particular importance is that recent winter temperatures are above the freezing point, indicating no or little sea ice in the southeastern Bering Sea for the previous four years (Fig 2 (b))….”
    http://www.beringclimate.noaa.gov/bering_status_overview.html

    Comment by Hank Roberts — 18 Dec 2007 @ 4:41 AM

  129. Re 125: Phil: 552 cubic km vs. 1.5 million square km ??

    In my opinion the Arctic Ocean change is indeed passing a tipping point. A rough outline would be as follows:

    A climate system of two physical seasons (“winter” and “spring” only) is developing into a 4 seasons system.

    In the “old” process the WINTER season was very clear. Ice and snow covered sea surface, no solar energy input (heat transport by the winds from lower latitudes), radiative cooling from cold (like -20 degC) surfaces is determined by the greenhouse gases. Albedo is high but not relevant. Little evaporation. No wind driven mixing of sea water. Hard fresh water ice forming at times on the surface and gradually replacing older one.

    SPRING season with wet ice floes, little open water and some wet snow, high albedo. Solar energy input 24/24, heat transport to the area also by winds, Out-radiation from surfaces at 0 degC. Evaporation from water surface (predominantly fresh water). Little wind driven mixing of sea water, low wind traction to sea surface circulation.

    The new SUMMER season brings open water. Low albedo meets 24/24 solar input, outwards radiation from sea surface a few deg above 0 degC. Wind driven mixing of surface waters and strong wind traction to speed up the larger scale circulation. Higher evaporation rate, also start generating salt particles that act as condensation nuclei.

    The new AUTUMN season is likely to be short initially. Surface waters cool and new (softer) ice is formed from saline sea water. Energy input is initially from sea and air currents from lower latitudes as the solar input goes to zero. Wind driven mixing of surface waters helps cool the water top layer until ice forms.

    Where did the extra heat captured in 2007 go? Most of it still circulates in the Beaufort gyre, in the uppermost 50 meters of the ocean. It is not efficiently leaked out via the surface as there is a layer of heat insulation (ice and snow) above it. (Ice formed rather rapidly). There is little mixing so it moves downwards very slowly. How it will express itself next spring will be interesting to see.

    Comment by Pekka Kostamo — 18 Dec 2007 @ 4:44 AM

  130. Re#125
    552 kubic, not square km. I don’t know if it’s true, but we’ll find out from the press release tomorrow.

    Comment by Elmar — 18 Dec 2007 @ 7:34 AM

  131. Chris posts:

    [[Steve, we really do not know the ultimate reason for the decreased cloud cover this year. ]]

    Could it have anything to do with ocean die-off, and maybe reduced production of DMS by algae? If anyone remembers that theory…

    Comment by Barton Paul Levenson — 18 Dec 2007 @ 10:39 AM

  132. Tilo posts:

    [[How do you select a timescale to determine if a trend is significant? Let’s say we throw out the El Nino year of 1998. Then we are saying that the slope established in the 22 years from 1975 to 1997 is significant, but the slope established in the 8 years from 1999 to 2007 is not. Somehow that doesn’t have a good intuitive feel to it.]]

    You wouldn’t throw out the 1998 point. It’s still a valid data point. You’d just start early enough to get a significantly large sample.

    Comment by Barton Paul Levenson — 18 Dec 2007 @ 10:42 AM

  133. Tilo also posts:

    [[The other thing that I wonder about is the modelers desire to use a 0.018 deg.C/yr CO2 forcing factor.]]

    They don’t “use” a forcing, forcing is one of the outputs of the run.

    [[ And let’s say I accept that. But CO2 forcing is not linear. Supposedly the frequency band that CO2 is good at absorbing is already mostly absorbed by the current level of CO2. So more and more CO2 gives us less and less forcing. Can we know that there is enough residual forcing in CO2 to maintain a 0.018 deg.C/yr slope for any significant number of years?]]

    Yes.

    Comment by Barton Paul Levenson — 18 Dec 2007 @ 10:44 AM

  134. “The polar bears are on land, and eat very little if at all, during those months. Then when it freezes, off they go. Mmmmmm, fat juicy seal, smack-smack, chew-chew, tastes good after not eating for so long!”

    re #127 Hi dhogaza. I probably wasn’t clear with my question. Since Hudson bay is ice free 3 to 4 month a year, it’s eco system would undergo the same change with regards to microorganisms as the pole if it melted 3 to 4 month a year. Since Hudson bay has no problems supporting all the life forms required to create the food chain all the way up to the seal and the polar bear, then could the arctic also create such a food chain in the abscense of the microorganisms that live in the ice. Phytoplankton might be the right candiate for the bottom of that food chain.

    But concerning the polar bears, one of the bloggers in Churchill mentioned that the bears killed 11 seals there while waiting for the pack ice to form up this year. I’m sure that their hunting success goes way down without the ice, but it’s good to know that they’re not completely helpless. He also said that the bears left to go out on the ice on 17th Nov. this year. The norm in the past was around the 14th of Nov.

    Comment by Tilo Reber — 18 Dec 2007 @ 11:17 AM

  135. Ref 124 Steve Bloom writes “That will be decided by the data that comes out in the next 2 to 3 years.” and
    “Can we know that there is enough residual forcing in CO2 to maintain a 0.018 deg.C/yr slope for any significant number of years?” Your analysis is absolutely right. Thanks to Bali, pretty well all nations of the world will follow their own ideas of what to do about ghgs. Which means that ghgs are going to continue to rise at the same rate, or even faster than they have done for the first part of the 21st century. We will carry out the “experiment” to see what happens with ever increasing quantities of CO2 in the air; at least until Copenhagen in 2009. How long it will be before we know whether temperatures are actually dropping is not known, but maybe if the amount of ice in the arctic is more in Sep 2008 than it was in Sep 2006, people may want to take a good look at what is happening to global temperatures. The latest data fron NCDC/NOAA for November 2007, shows that the trend towards lower temperatures which has persisted for the whole of 2007 is continuing. Year to date, 2007 is the 4th warmest on record. There is still no sign of rising world temperatures in the 21st century.

    Comment by Jim Cripwell — 18 Dec 2007 @ 11:58 AM

  136. Tilo, Nature does not deal with anecdotal success–e.g. 11 kills by a few polar bears at a particular time and place. What matters is whether food supply sustains a genetically viable population. If not, the species adapts or dies. Ecosystems have a remarkable way of persisting. The question is whether those ecosystems that survive are also conducive to human survival and to our aesthetic preferences as well. I suppose we’ll always have the cockroaches and the rats.

    [Response: And the bacteria. Don’t forget the bacteria. After reading Andy Knoll’s book on Early Earth ecosystems, I realized that we’re all basically guests of the prokaryotes. –raypierre]

    Comment by Ray Ladbury — 18 Dec 2007 @ 12:22 PM

  137. So, Jim Cripwell, we are still waiting to hear what you would consider “evidence” for ghg as the cause of the current warming epoch. You seem to be putting a whole helluva lot of emphasis on how much ice we have in Sep. 2008. Would that be your proof? You also keep saying there’s no sign of warming in the 21st century. Aside from being an incorrect assertion, would a convincing warming trend after, say 2005 be your proof? If so, for how long?

    Comment by Ray Ladbury — 18 Dec 2007 @ 12:26 PM

  138. NASA’s Goddard Institute for Space Studies (GISS) predicted yesterday that 2007 will be Earth’s second-warmest year on record. – http://sciencenow.sciencemag.org/cgi/content/full/2007/1211/3

    Comment by J.C.H. — 18 Dec 2007 @ 12:59 PM

  139. Re #126. Steve, can you point me to the Maslowski reference you’re referring to?

    Comment by Chris O'Dell — 18 Dec 2007 @ 1:18 PM

  140. Would someone be able to give me a simple layman’s explanation of why the rate of ice melt and glacial retreat in Greenland (and elsewhere in the Arctic) does not exactly match the temperature record? That is, the hottest years in Greenland seemed to be around 2002-2004, but the fastest race of ice melt appears to be a several years later (this is using the GISTEMP data along with the GRACE observations). I can think of various possible explanations, but I’d prefer to have an expert confirm the correct one.

    Comment by Dylan — 18 Dec 2007 @ 2:52 PM

  141. “Nature does not deal with anecdotal success–e.g. 11 kills by a few polar bears at a particular time and place. What matters is whether food supply sustains a genetically viable population.”

    I’m with you Ray. I don’t wish to suggest that the PB can survive without ice. I certainly don’t believe that they can. I was simply surprised to hear that they can do some level of hunting without ice. But in the long run, I’m convinced that they would die off without the ice. It appears that the annual iceless interval through which a population can sustain itself is around 3 to 4 month.

    Comment by Tilo Reber — 18 Dec 2007 @ 4:16 PM

  142. Re #139: Maslowki et al’s AGU presentation was U33B-04 and had a somewhat uninformative abstract, but this BBC article summed things up nicely. Also, this AP article has several interesting quotes from some senior scientists. See also this article regarding session U33B-01 on warm water intrusion.

    Comment by Steve Bloom — 18 Dec 2007 @ 4:21 PM

  143. Plus they had a second presentation on validating their model:

    (C22A-06) “Understanding Recent Variability in the Arctic Sea Ice Thickness and Volume – Synthesis of Model Results and Observations

    “We examine the diminishing sea ice thickness trend in the Arctic Ocean using results from the NPS 1/12-degree pan-Arctic coupled ice-ocean model. While many previous studies have analyzed changes in ice extent and concentration, this research focuses on ice thickness as it gives a better indication of ice volume variability. The skill of the model is evaluated by comparing its ice thickness output to actual sea ice thickness data gathered during the last three decades. This includes the model comparison against the most recently released collection of Arctic ice draft measurements conducted by U.S. Navy submarines between 1979 and 2000. Our model indicates an accelerated thinning trend in Arctic sea ice during the last decade. This trend is robust and independent of timescales for surface temperature and salinity relaxation. The validation of model output with submarine upward-looking sonar data supports this result. This lends credence to the postulation that the Arctic is likely to be ice-free during the summer in the near future.”

    While I’m at it here’s the abstract from the first session:

    (U33B-04) “On the Relative Importance of Freshwater Fluxes and Variability From the Arctic Ocean into the North Atlantic

    “We use a high resolution coupled ice-ocean model of the Pan-Arctic region forced with realistic atmospheric data to investigate the variability of freshwater content within the Arctic Ocean as well as sea ice and liquid freshwater fluxes into the North Atlantic during 1979-2004. Modeled fluxes are validated against recently published estimates. Results are analyzed to compare the relative contribution of the total combined liquid and solid freshwater flux through the two main pathways: Fram-Denmark Strait (FDS) and the Canadian Arctic Archipelago- Davis-Hudson Strait (CAADHS). Our results suggest the relative importance of the freshwater flux through CAADHS into the Labrador Sea. This implies the need for ocean models to adequately represent mass and property fluxes through the narrow and shallow passages of the Canadian Archipelago and Davis and Hudson Straits. We argue that this requirement must be satisfied to advance studies of the Atlantic Meridional Overturning Circulation (MOC) and especially its variability. Given the recent record sea ice melt in the Arctic Ocean, it is critical that global ocean and climate models improve their skill in simulating and predicting effects of changing exports from the Arctic Ocean into the North Atlantic.”

    It’s maslowsk[at]nps.edu, BTW.

    Comment by Steve Bloom — 18 Dec 2007 @ 5:04 PM

  144. Re#129
    Pekka Kostamo Says:
    18 December 2007 at 4:44
    “Re 125: Phil: 552 cubic km vs. 1.5 million square km ??”

    The original quote was 552 billion tons or ~552×10^9 m^3 if we estimate the average thickness of the ice melted this year as 1m (very conservative) then 1.5 million sq. km is 1.5×10^12 m^3

    Comment by Phil. Felton — 18 Dec 2007 @ 5:29 PM

  145. Re#135

    Jim, most people on this forum will disagree with me, but I’m glad that we get to extend the experiment for a couple of years. Here is my reasoning (or lack thereof). We are currently at or near a solar minimum. Solar cycle 24 has been delayed by at least a year, and it may be delayed longer. We have had low solar activity for much of this year, and it will probably contiue for a while longer. There are split opinions on cycle 24, but many people believe it will be a weak cycle. If it is a weak cycle, then we will get a chance to gather some evidence about the relative strength of solar forcing vs CO2 forcing. If CO2 forcing dominates solar forcing, then we should continue to have temperature go up during this time. If it doesn’t, then we may actually turn around and go down for some period of time – even with the current levels of CO2. I believe that the IPCC position is that CO2 is the driving factor for global warming and solar forcing is too weak to reverse it. There are a few people who disagree with that. I’m anxious to have the empirical evidence, and the next couple of years just may provide some of it.

    Comment by Tilo Reber — 18 Dec 2007 @ 6:25 PM

  146. Here is a form of ‘tipping’ which simply is not publized enough:

    http://blogs.nature.com/climatefeedback/2007/12/coral_reefs_are_on_the_ropes.html

    Comment by David B. Benson — 18 Dec 2007 @ 6:47 PM

  147. > if CO2 forcing dominates solar forcing, then we
    > should continue to have temperature go up during
    > this time.

    Well, you’re leaving out other factors and other predictions for the same time span, aren’t you?

    This, I think, takes the range of likely solar influence into account, and they think it’s minor:

    http://inel.wordpress.com/2007/08/09/hadley-centre-decadal-climate-prediction-system/

    Comment by Hank Roberts — 18 Dec 2007 @ 6:54 PM

  148. Re #147. “Well, you’re leaving out other factors and other predictions for the same time span, aren’t you?”

    Yes I am. But CO2 and solar forcing seem to be one major place where opinions diverge.

    “This, I think, takes the range of likely solar influence into account, and they think it’s minor:”

    It will be interesting to see if the new model works. Obviously how well they estimate the different forcing factors will play into that.

    From one of the referenced articles:

    “The climate projection, published today in the journal Science, suggests that a natural cooling trend in eastern and southern Pacific ocean waters has kept a lid on warming in recent years.

    And it will continue to do so, scientists say, but not for long.”

    I wonder what “a natural cooling trend” is?

    Comment by Tilo Reber — 18 Dec 2007 @ 7:47 PM

  149. Phil Felton @ 144: yes, the volume of sea ice melt is much greater than the Greenland mass imbalance. But many millions of square kilometres of sea ice melt every year (typically about 7 million), and the thickness of the ice which does not melt also varies with the seasons. In terms of volume, several tens of percent of the total sea ice melts – and refreezes – every year. It’s a very dynamic system, so it doesn’t need to be thrown very far out of balance to fall off a cliff: losing all the sea ice is only a factor of two or three away from the normal dynamic range.

    In comparison, the Greenland ice sheet is approximately balanced. It has a total of 2-3 million cubic kilometres of ice (a hundred or so times the total sea ice volume), and yet annual variations are usually only in the tens of cubic kilometres (because it’s in a deep freeze, the main ice mass processes are snowfall and glacier flow, not melt and freeze): much less than one percent of the total.

    The “552 billion tons” number is important because it is considerably outside past records, showing that the usual balance of the GIS has become an imbalance. The mechanisms are a combination of surface melt and accelerated ice flow.

    If the ice sheet pessimists are right – and they have some good arguments and models on their side – this number is a portent of serious ice loss to come.

    So the difference is this: we are losing sea ice right now (in ten years or less it may be all gone) whereas the GIS is still with us (the fear is that in ten or twenty years we might be seeing thousands or tens of thousands of cubic kilometres of annual loss). Personally I’m filing the GRACE numbers away as a benchmark, something to which to compare future ice imbalance numbers, as the ice flow accelerates.

    Comment by Nick Barnes — 18 Dec 2007 @ 7:50 PM

  150. Tilo Reber (148) — I’ll hazard the amateur opinion that the ‘natural cooling trend’ is related to the upwelling of cold bottom water off the west coast of South America.

    Comment by David B. Benson — 18 Dec 2007 @ 8:00 PM

  151. Re #150

    David, if you are talking about La Nina, I don’t think that is suppose to be a condition lasting several years. Notice the quote said “The climate projection, published today in the journal Science, suggests that a natural cooling trend in eastern and southern Pacific ocean waters has kept a lid on warming in recent years.”

    Comment by Tilo Reber — 18 Dec 2007 @ 9:14 PM

  152. Tilo Reber (#148) wrote:

    “The climate projection, published today in the journal Science, suggests that a natural cooling trend in eastern and southern Pacific ocean waters has kept a lid on warming in recent years.

    And it will continue to do so, scientists say, but not for long.”

    I wonder what “a natural cooling trend” is?

    David B. Benson (#150) wrote:

    Tilo Reber (148) — I’ll hazard the amateur opinion that the ‘natural cooling trend’ is related to the upwelling of cold bottom water off the west coast of South America.

    Sounds about right:

    The Hadley group tested the usefulness of their new prediction model by “hindcasting” the climate of two past decades. Starting from the observed distribution of ocean heat content, the model outperformed its own forecasts that lacked observed initial conditions. Errors in predicting global temperature declined by 20% or 36%, depending on the type of error. The model successfully predicted the warming of El Niño and the effect of unusually warm or cold waters around the world. An actual forecast starting in June 2005 correctly predicted that natural variability— the appearance of cooler water in the tropical Pacific and a resistance to warming in the Southern Ocean—would offset greenhouse warming until now. But beyond 2008, warming sets in with a vengeance. “At least half of the 5 years after 2009 are predicted to be warmer than 1998, the warmest year currently on record,” the Hadley Centre group writes.

    Kerr, Richard A, Climate Change: Humans and Nature Duel Over the Next Decade’s Climate,
    Science. 2007 Aug 10;317(5839):746-7

    Unfortunately, that is about the only thing the article says regarding the lull before the storm. Haven’t been able to find out anything else as of yet.

    Comment by Timothy Chase — 18 Dec 2007 @ 10:04 PM

  153. http://www.cdc.noaa.gov/people/klaus.wolter/MEI/
    Last update: 5 December 2007

    “Here we attempt to monitor ENSO by basing the Multivariate ENSO Index (MEI) on the six main observed variables over the tropical Pacific. These six variables are: sea-level pressure (P), zonal (U) and meridional (V) components of the surface wind, sea surface temperature (S), surface air temperature (A), and total cloudiness fraction of the sky (C). These observations have been collected and published in COADS for many years.”

    http://www.cdc.noaa.gov/people/klaus.wolter/MEI/ts.gif

    http://www.cdc.noaa.gov/people/klaus.wolter/MEI/lanina.gif
    “… The 1998-2000 La Niña does not resemble any previous event in this comparison figure. It started late (about three months later than the previous latest case), and it featured a superimposed annual cycle (peaking around May and troughing around November) that does not match the other events…”

    “The most recent El Niño event of 2006-07 reached a similar peak as the 2002-03 event, but lacked ‘staying power’, and collapsed rather early in 2007….”

    Comment by Hank Roberts — 18 Dec 2007 @ 10:37 PM

  154. Re #146
    Thanks for the link David. But it seems that for every opinion there are other opinions. I think it is important to note that more coral reefs grow in warm water than in cold; that coral reefs have risen with the sea level since the last ice age; and that some people believe that bleaching can sometimes be a survivable process whereby one form of algae is swapped for another form of algae that is more capable of dealing with the modified temperature.

    In any case, here are some links to use as a contrast to your link.

    http://www.theaustralian.news.com.au/story/0,25197,22065659-5006786,00.html
    http://www.sciencedaily.com/releases/2007/11/071129183829.htm
    http://www.sciencedaily.com/releases/2006/06/060623094718.htm

    [Response: The fact that some particular kinds of coral may resist damage from warming does not allow one to conclude that the coral ecosystem will remain healthy in a thriving environment. There are always survivor species — ferns made it through the Permo-Triassic mass extinction, lots of other plants we
    live with now almost didn’t. If you read the “related stories” on the sciencedaly dispatch, you’ll get a more balanced view of the magnitude of the problem than you’d get from the distorted spin Mr. Reber puts on it. –raypierre]

    Comment by Tilo Reber — 18 Dec 2007 @ 11:53 PM

  155. Ref 145 Tilo writes “I’m anxious to have the empirical evidence, and the next couple of years just may provide some of it.” Bravo!! I believe the IPCC position is that the ONLY solar effect is a change in TSI. There is so much bias in the media, that a “tipping point” may occur when the general public realize that maybe, just maybe, global temperatures are not going up after all, and certainly not as fast as the proponents of AGW suggest.

    Comment by Jim Cripwell — 19 Dec 2007 @ 7:31 AM

  156. Jim Cripwell posts:

    [[There is still no sign of rising world temperatures in the 21st century.]]

    Unless you actually do the math.

    http://members.aol.com/bpl1960/Ball.html

    Comment by Barton Paul Levenson — 19 Dec 2007 @ 9:09 AM

  157. Tilo posts:

    [[If it is a weak cycle, then we will get a chance to gather some evidence about the relative strength of solar forcing vs CO2 forcing. If CO2 forcing dominates solar forcing, then we should continue to have temperature go up during this time. If it doesn’t, then we may actually turn around and go down for some period of time – even with the current levels of CO2. I believe that the IPCC position is that CO2 is the driving factor for global warming and solar forcing is too weak to reverse it. There are a few people who disagree with that. I’m anxious to have the empirical evidence, and the ]]

    What’s wrong with the past 400 years of empirical evidence? Yes, the sun affects climate, no, it isn’t driving the current warming.

    Comment by Barton Paul Levenson — 19 Dec 2007 @ 9:13 AM

  158. > But it seems that for every opinion there are other opinions.
    > — T. Reber, above

    “You are entitled to your opinion. But you are not entitled to your own facts.” – Senator Daniel Patrick Moynihan.

    Comment by Hank Roberts — 19 Dec 2007 @ 10:57 AM

  159. Jim Cripwell wrote: “There is still no sign of rising world temperatures in the 21st century.”

    If find it very admirable that the moderators and participants on this site who are actually knowledgeable about climate science, rather than being steeped in ideologically-driven denialist sophistry, consistently respond to such baseless assertions with patient, polite, informative comments.

    Comment by SecularAnimist — 19 Dec 2007 @ 11:55 AM

  160. Re #158
    “You are entitled to your opinion. But you are not entitled to your own facts.”

    I agree completely Hank. But the facts are not always that easily determined. For example, one would think that modern temperature data sets are facts. So on the one hand I can look at RSS and UAH data that is extremely closely correlated, or I can look at GISS data which currently has a bias to the warm side by somewhere between .2 and .3Deg.C, and whose divergence seems to be increasing, when compared to the previous two. Which data set is fact? Or, I can accept the fact that CO2 is a greenhouse gas that contributes to warming; but what is the fact of how much it contributes. James Hansen tells us that it is between 2 and 4 deg C per doubling of CO2. Most of the guys at the Physics forum who have run the numbers; people who have run it through the Modtran software; and others, seem to think that the number is between .7 and 1.5 deg C per doubling of CO2.

    Those facts would seem to be important when you are predicting future outcomes. But since they don’t seem to be well nailed down, there is room for opinion.

    [Response: This response is exactly what Hank is talking about. Modtran cannot give you climate sensitivity since it doesn’t contain any feedback mechanisms. That is a fact. Thinking is it just a matter of opinion whether it does or not, is just wrong. The ‘fact’ that GISTEMP anomalies have an offset from UAH anomalies is due to a different reference period. It is not a matter of opinion whether that is important (it is not). Etc. By looking into the details of these issues it is possible to determine what is fact and what is opinion, but your reading on these issues is inadequate to the task. You can get pointers on how to do it better from comments here or by reading the technical literature (rather than in a forum), but you need to approach it with an open mind. Good luck. – gavin]

    Comment by Tilo Reber — 19 Dec 2007 @ 12:48 PM

  161. > in the 21st century

    But you aren’t claiming that means anything, because you know it’s a capital fault to pick less than all the available information, right? You wouldn’t try to fool us here, would you?

    If your banker insisted on showing you only selected months for your retirement money’s returns, you’d squawk, right? You’d want the whole period. Economists warn about this same error often.
    Example:
    http://www.econbrowser.com/archives/2007/12/ntsds2.gif

    Comment by Hank Roberts — 19 Dec 2007 @ 1:37 PM

  162. RSS UAH is cold lately hey? Well the stratosphere in the Northern Hemisphere is extremely cold, is no coincidence, it is said that this MSU reading is confused with the stratosphere, deja vue boasting!

    144-149 The astronomical Arctic sea ice melt of 2007 masks the certain fact that if the winds were Southwards instead of Northwards, 2007 would have been the warmest year in history worldwide, not just for the Northern Hemisphere as it now stands, despite a quiet sun and La Nina. I am quite keen on an official calculation which will state how much Global Temperatures was reduced by this melt.

    Comment by wayne davidson — 19 Dec 2007 @ 1:53 PM

  163. Tilo Reber posts:

    [[James Hansen tells us that it is between 2 and 4 deg C per doubling of CO2. Most of the guys at the Physics forum who have run the numbers; people who have run it through the Modtran software; and others, seem to think that the number is between .7 and 1.5 deg C per doubling of CO2.]]

    Sai Tilo, you are comparing doubling CO2 by itself (MODTRAN) to doubling it with water vapor, albedo and other feedbacks (Hansen). They aren’t the same number. Houghton (“Global Warming: The Complete Briefing,” 2004) says the figure is 1.2 K for CO2 alone and 2.5 with feedbacks. I think the IPCC says 1.2 and 2.0-4.5.

    Comment by Barton Paul Levenson — 19 Dec 2007 @ 2:17 PM

  164. Yes, Wayne, that’s an interesting point. We are beginning to get estimates of the amount of ice melt. How much heat went into that, and was it enough to “take the top off” global temperatures?

    Comment by Gareth — 19 Dec 2007 @ 2:35 PM

  165. RE:#155
    “I believe the IPCC position is that the ONLY solar effect is a change in TSI.”

    There may be something to that Jim. Looking at the chart I’ve linked, (if it’s correct) it shows that the irradiance for the solar lows of the last 50 years is still higher that the irradiance of the solar highs that we achieved in the 19 century. Of course by the same token, the chart may explain much of the warming pattern that we have seen in the 20th century.

    http://www.junkscience.com/Greenhouse/irradiance.gif

    There may be other factors involved, such as feedback from the rise in TSI. I’m talking way over my head here, but there are some other phemomena that may be playing a part. For example, I have heard that at times there are things that look like magnetic ropes that attach from the sun to the earth, and that energy can flow across these from the sun to the earth. But like I said, I’m way over my head on that. I think Leif Svalgaard is one of the authorities on the subject, if you want to know more.

    Comment by Tilo Reber — 19 Dec 2007 @ 3:49 PM

  166. Ref 156. You will have to do better than that if you are going to convince me. I know no-one on RC will ever agree that world temperatures have stabilized, let alone, horror of horrors, actually decreased. But there are at least four sets of data on average global temperature anomalies; NASA/GISS, NCDC/NOAA, HAD/CRU, and satellite MSU/RSS. These are not well correlated, and the correlations have become poorer in recent years. I have searched, but cannot find any study that compares and contrasts the different methods. If you want to convince me, you need to either produce a study which shows that the NASA/GISS data is undoubtedly the closest to reality, or a strudy which shows that all four sets of data give the same result.

    Comment by Jim Cripwell — 19 Dec 2007 @ 3:54 PM

  167. Jim Cripwell writes:

    [[ But there are at least four sets of data on average global temperature anomalies; NASA/GISS, NCDC/NOAA, HAD/CRU, and satellite MSU/RSS. These are not well correlated, and the correlations have become poorer in recent years. I have searched, but cannot find any study that compares and contrasts the different methods. If you want to convince me, you need to either produce a study which shows that the NASA/GISS data is undoubtedly the closest to reality, or a strudy which shows that all four sets of data give the same result.]]

    Try graphing them all. Ts against time, averaged over 12 months.

    The NASA/GISS figures include the poles, which I believe the HAD/CRU doesn’t.

    Comment by Barton Paul Levenson — 19 Dec 2007 @ 4:37 PM

  168. Re #166 (Jim Cripwell) “I know no-one on RC will ever agree that world temperatures have stabilized, let alone, horror of horrors, actually decreased.”

    Er, we would if they had, Jim, but unfortunately they haven’t. Even though I don’t enjoy being proved wrong any more than most people, I’d much rather be wrong than right on AGW. Although I’ll probably be dead from natural causes before it causes mass starvation and nuclear war (unless we take prompt and in many ways painful action), my 12 year old son very likely won’t be.

    Comment by Nick Gotts — 19 Dec 2007 @ 4:52 PM

  169. Jim C,

    You’re going to have to start posting under a different name or a pseudonym if you’re going to convince anyone here that you can be convinced of anything that doesn’t involve undescribed, unobserved, non-human related factors for which we have no evidence accounting for climate change, (presumably we shouldn’t rule out UFO’s or cattle mutilations). As it is, after myriad occasions of having fatuous solar assertions blown up, you were asked a pretty simple question- describe an experiment whose outcome would count as evidence in support of the theory of AGW in your mind. You answer was so conspicuous a dodge it it’d make Bill Clinton blush. The prosecution rests.

    Tilo,

    Was that a skeptical argument or a parody of a skeptical argument? It’s getting so they are difficult to tell apart.

    Comment by Majorajam — 19 Dec 2007 @ 4:58 PM

  170. Majorajam wrote: “… undescribed, unobserved, non-human related factors for which we have no evidence accounting for climate change, (presumably we shouldn’t rule out UFO’s or cattle mutilations).”

    Actually there is a “theory” that extraterrestrials are covertly present on Earth, where disguised as humans they have infiltrated industry and government and manipulated human technologies so as to deliberately raise the levels of carbon dioxide and methane, thereby making the Earth’s atmospheric & oceanic chemistry and climate hospitable to their alien physiology, while at the same time the effects of climate change will decimate the human population over the next century, in preparation for their large-scale invasion and colonization of the Earth.

    There is as much evidence for that “theory” as there is for some of the other “theories” offered by the deniers. Plus it has the virtue of explaining why some people, such as oil company executives, are acting as they are: it’s because they aren’t really human.

    Comment by SecularAnimist — 19 Dec 2007 @ 6:28 PM

  171. > magnetic ropes
    http://news.yahoo.com/s/afp/scienceastronomyus

    “David Sibeck, project scientist at NASA’s Goddard Space Flight center….’We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras,’ he told the annual meeting of the American Geophysical Union.”

    We know energy from the Sun gets here. This is a ‘how’ not a ‘more than we knew existed’ report.

    Comment by Hank Roberts — 19 Dec 2007 @ 6:29 PM

  172. ENSO is mistakenly described as a Pacific Ocean phenomenon. The cooling and warming tendency manifests across the entire tropical region in all major oceans as can be seen if one looks at current sea surface temperature anomalies. It is amplified in the Pacific by the northward shift of the west wind drift increasing the volume of water in the Humboldt Current. Ocean temperatures fall in both the western and the Eastern Pacific during a La Nina event. In an El Nino event sea surface temperatures rise in both the East and the West, as they do across all tropical latitudes apparently in response to a widening cloud free atmospheric window.

    ENSO phenomena relate strongly to the aa index of geomagnetic activity and are driven by the sun. The last three solar cycles have been El Nino dominant. The next three will be La Nina dominant as the magnetic field of the sun declines. To check this cyclic activity for yourself simply add the monthly values of the SOI for each solar cycle since 1880 and graph the result. The cyclical effect will then manifest.

    The biggest response to low latitude temperature change is seen in the northern hemisphere north of Latitude 60°. This is simple stuff. Arctic sea ice will recover shortly. Stop worrying about your carbon footprint. It’s a red herring.

    Comment by Erl Happ — 19 Dec 2007 @ 8:13 PM

  173. Seems my last post got missed, so I’ll try again…does anyone know why is that the rate of ice sheet melting in Greenland has been accelerating the last 4 years, while the annual temperature in most of Greenland has actually fallen slightly in the same period? Is there a lag, or is it because of hotter/longer summers (despite a slight annual downtrend), or because the temperatures in the more northerly regions (which have increased slightly in the last 4 years) matter more? Or because ice sheet melt is complex and responds to lots of different factors other than surface air temperature?

    As a bonus, is there any evidence about rate of ice sheet melt in Greenland in 1930’s which saw similarly warm temperatures?

    Thanks in advance.

    Comment by Dylan — 19 Dec 2007 @ 8:31 PM

  174. Dylan, water doesn’t melt from an average summer temperature, it melts from a local daily temperature.

    So start where you got your information — where was that? If you’ll give us the source we can help check it out. It may be you’re not getting good information, or the aren’t giving you the footnotes to check the source.

    Google Scholar is often helpful; you can limit it to ‘recent’ and even by year. This is a search for articles in Scholar dated 2007 using
    summer greenland melt
    See what you think:
    http://scholar.google.com/scholar?hl=en&lr=&safe=off&scoring=r&q=summer+Greenland+melt&as_ylo=2007

    Also, you can then click “Images” and see
    http://images.google.com/images?tab=si&sa=N&hl=en&lr=&safe=off&q=summer+Greenland+melt&as_ylo=2007

    So, you can see from this that there’s more water melting during the summers. Does that help understand why the glaciers may be moving more?

    Look back at the place you got the original information — this is a good chance to practice skepticism. Did they give you enough information to think this through for yourself? If not — glad you asked here.

    I’m just an amateur reader here. Whatever I’ve gotten wrong or missed, I expect correction promptly.

    Can’t help you with the 1930s, but that’s because I don’t have time to look right now. There weren’t any satellites, lots less info, so it may be harder to say.

    Comment by Hank Roberts — 19 Dec 2007 @ 9:13 PM

  175. First, thanks to Raypierre for giving all of us an eyewitness report of the AGU meeting and all the interesting and sometimes scary science there. Its good for the people who are interested in the science, the public debate about the science, and the political implications of the science to have a window into the scientific community. Second when ptarmigans came up again, I did remember the earlier post. I did a quick google search on Ken Tape to make sure it wasn’t another joke. It wasn’t. Fool me once, shame on you. Fool me twice… ;)

    #154 (Tilo Reber) The comments about coral reefs bring up some good points. First the Climate Feedback link David Benson (#146) included was about the recent issue of Science and the review paper on the status of coral reefs. For someone trying to learn about the issue and does not have any background on the science involved, a review paper like the one discussed on Climate Feedback should be given more weight than individual studies like those cited by Tilo Reber.

    As someone who does have some scientific training in this area, I think the review paper is a more accurate view of the status of coral reefs because it includes all the threats to coral reefs. You can see the whole picture only when you look at all the pieces.

    Comment by Joseph O'Sullivan — 19 Dec 2007 @ 9:19 PM

  176. Hank, my previous post explained where I got the info – from the GISTEMP site, and the GRACE satellite measurements.

    You say “water doesn’t melt from an average summer temperature, it melts from a local daily temperature” – but surely, all else being equal, the higher the average temperature over the summer period, the faster water will melt? And as I said, looking at the GISTEMP individual station data on a month by month basis, the summers have in fact been getting hotter over the last 4 years – however colder temperatures in the winter have meant that the annual mean temperature has sloped off slightly in the same period.
    It seems logical that only temperatures ABOVE zero matter when considering ice melt, so on the surface this is the best explanation – but like I said, I’m not an expert, and would prefer not to guess.

    Comment by Dylan — 19 Dec 2007 @ 10:31 PM

  177. Re the decline of coral reefs in 175 154 and 146, other stressors include nutrient loading with attendant algae blooms that coat and kill coral polyps, in addition to direct human destruction in the form of cyanide and dynamite fishing.

    The idea that the “white desert” of bleached coral reefs will spontaneously resurrect in warmer, more acidic waters, is wishful thinking.

    Comment by Jim Galasyn — 20 Dec 2007 @ 12:15 PM

  178. > GISTEMP …
    > surely, all else being equal, the higher the
    > average temperature over the summer period,
    > the faster water will melt?…
    > … only temperatures ABOVE zero matter

    How many stations are there on the Greenland icecap?
    Most of the data I know about comes from the satellites.
    The images I pointed to show that information.

    Comment by Hank Roberts — 20 Dec 2007 @ 3:56 PM

  179. Hank, I don’t know – there’s no easy way of determining this. It would be nice if GISTEMP provided a map showing where the stations were.
    I’ve tried accessing raw satellite data before, and that was a real pain, if you know of a site that has it available in a user-friendly manner please tell!

    This map gives an idea of what land-based measurements are available, and also demonstrates that even summer temperatures have cooled considerably across much of Greenland:

    http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2007&month_last=11&sat=4&sst=0&type=trends&mean_gen=0506&year1=2002&year2=2006&base1=1951&base2=1980&radius=250&pol=reg

    On that basis, it’s a bit hard to understand what could be driving the faster melt rate.

    Comment by Dylan — 20 Dec 2007 @ 10:30 PM

  180. Re#171
    ’We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras,’

    Thanks Hank. I had lost my link to that one. In any case, my objective was not to say that this phenomena caused global warming, but to point out that there are many factors that play into to global energy equation that we don’t yet fully understand.

    Comment by Tilo Reber — 20 Dec 2007 @ 10:50 PM

  181. The basic features of the newly reformed Arctic Ocean ice make it a new ice world loaded with leads, there is a chance to see them now on this site (http://www.weatheroffice.gc.ca/data/satellite/hrpt_dfo_ir_100.jpg) while it is colder (light winds), sat images are fairly clear, a RADARSAT shot would bring out the real chaotic state though. This is a real changed ice scape, with implications already known through very capable RC contributors, winds bring out heat , no winds allow cooling to take place. Those extra leads are the main characteristic so far.

    Comment by wayne davidson — 20 Dec 2007 @ 11:38 PM

  182. Actually that link had not just summer, but the whole period May-Oct. If you just look at Jun-Aug, it does show a warming patch in the SE, but still, hardly a consistent pattern. Perhaps if it was filtered to only temperatures above 0, it would be different.

    http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2007&month_last=11&sat=4&sst=0&type=trends&mean_gen=0603&year1=2002&year2=2006&base1=1951&base2=1980&radius=250&pol=reg

    Comment by Dylan — 21 Dec 2007 @ 12:21 AM

  183. #179 Dylan,

    If you use GISS as you linked to:
    http://data.giss.nasa.gov/gistemp/maps/

    Set up and make this map.
    Land – GISS Analysis,
    Ocean – none
    Map Type – Trend
    Mean Period – Spring March – May
    Time interval – 2002-2006 [your time period]
    Smoothing – 250km
    Projection – Polar

    It seems Greenland warms >2degC in the spring.

    Like Hank I’m just an amateur, but here’s what I’m thinking, 2 guesses:
    a)
    The key warming is in the spring. That wets the ice and lowers it’s albedo, so the ice absorbs more sunlight in the summer season. Even if you get a relative cooling of air temperature in the summer the ice has been pre-conditioned and melts more than it would otherwise. Because it’s ice melting on ice, the local air temperature doesn’t rise as much as if it were land or sea being revealed by the melt. This is because the ice melt reveals more ice, and melt water is in constant contact with the ice. It takes as much energy to melt an amount of ice as it does to raise it’s temperature from 0 to 80degC. So that powerful energy sink of an ice environment soaks up absorbed solar energy in melting ice.
    b)
    Also, here’s a Wiki jgp based on satellite data. http://en.wikipedia.org/wiki/Image:Arctic_Temperature_Trend_1987-2007.jpg
    That shows a strong warming over a greater period as measured by satellite. I’m wondering if satellite might make the cooling (which seems to be down to 1 station) appear much less significant. Because if the lower troposhpere MSU trends might be more representative of the temperautes up on the ice sheet (mean altitude about 2100metres). From my reading of the 250km smoothed plots it looks like there are 3 temperature stations. All apparently by the coast, i.e. not at altitude.

    Steffen Research Group host the Greenland Climate Network some are at altitude (not always working though). http://cires.colorado.edu/science/groups/steffen/gcnet/

    Anyone know when/if Steffen Research Group will update with this years Greenland Melt extent (as they have 2005/2)? http://cires.colorado.edu/science/groups/steffen/

    Comment by CobblyWorlds — 21 Dec 2007 @ 3:07 PM

  184. Thanks for that CobblyWorlds. I also received this email from a Norwegian glaciologist:

    “Very good that you are interested in what is happening with our polar areas. I think you have lined out many of the possible answers in your message! The Greenland ice sheet is large and indeed the dynamics very complex. Therefore it is difficult to single out one reason for the melting but it is little doubt that the meterological conditions during summer are playing a major role here. It is not only temperatures that are important but also wind, clouds, radiation, albedo….. Albedo is extremely important. Once the surface conidtions have changed from a white highly refelctive surface to a darker melting one it will warm up even faster because a dark surface attracts more solar radiation (heat) that a white one. This is a the most important feedback mechansim for polar areas.
    I hope this is helpful information for you.”

    Comment by Dylan — 21 Dec 2007 @ 11:35 PM

  185. On surface melting, changing albedo leading to faster melting,
    Steffen was in the news some months ago:
    http://cires.colorado.edu/news/press/2007/07-05-15.html
    Hansen:
    http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf
    Connolley on what he found lacking in Hansen’s paper:
    http://scienceblogs.com/stoat/2007/11/hansen_again.php#comments
    Blue ribbon panel considers extreme scenarios; nobody reported this:
    http://handle.dtic.mil/100.2/ADA473826

    Comment by Hank Roberts — 21 Dec 2007 @ 11:59 PM

  186. #184 A micro experiment to make this point would be adequate, take two ice cubes, freeze one at -5 C the other at -40 C, place them in the same ambiant air at the same time. Which of the two will melt completely first?

    This experiment can be carried on a glacier scale if only core temperatures were taken. Given a winter averaging at -40 C, compared to a winter at
    -30 C , how much more would the warmer glacier melt?

    Comment by Wayne Davidson — 22 Dec 2007 @ 1:10 AM

  187. A heated report full of tidbits:

    http://www.cbsnews.com/stories/2007/12/18/2007/main3629629.shtml

    Comment by J.C.H. — 22 Dec 2007 @ 11:39 AM

  188. Ref 167 Barton writes “Try graphing them all. Ts against time, averaged over 12 months.”. And in #156 also writes “Unless you actually do the math.” I have taken your advice. I collected the data from 2000 to 2007 for all four sets (NASA/GISS. NCDC/NOAA, HAD/CRU, and MSU/RSS). I assumed the 11 months of 2007 represent the whole year. I used a simple linear least squares regression analysis, starting in 2000, 2001, 2002 and 2003. Starting in 2000, all four sets give positive slopes, meaning rising temperatures. The NASA/GISS set gives positive slopes for all starting years. However, the other three sets, for all starting years 2001, 2002 and 2003 give negative slopes, meaning falling temperatures. It would seem that the NASA/GISS data is significantly different from the other three. It would also seem that the other three data sets indicate that world temperatures are falling in December 2007.

    Comment by Jim Cripwell — 22 Dec 2007 @ 1:03 PM

  189. Re # 186 Wayne Davidson: ” take two ice cubes, freeze one at -5 C the other at -40 C, place them in the same ambiant air at the same time. Which of the two will melt completely first?”

    I’m not a physicist, and I haven’t done the experiment, but comparing the thermal properties of ice at -5C and -40C suggest to me that the result may not be what you might predict:

    Thermal conductivity
    -5 C 2.25 W/mK
    -40C 2.64 W/mK

    Specific Heat
    -5C 2.027 kJ/kg/K
    -40C 1.818 kj/kg/K

    http://www.engineeringtoolbox.com/ice-thermal-properties-d_576.html

    Comment by Chuck Booth — 22 Dec 2007 @ 2:23 PM

  190. Re #188

    I would suggest to you that for ice at -40ºC to melt it must first pass through -5ºC.

    Comment by Phil. Felton — 22 Dec 2007 @ 8:35 PM

  191. 189-190, I side with Phil, but try the experiment Chuck, there is nothing like tactile impressions.
    If you don’t have a freezer that goes down to -40 C, try a different temperature range, the results will be similar.

    Comment by wayne Davidson — 22 Dec 2007 @ 10:08 PM

  192. Jim Cripwell, how many years are you graphing there?
    Are you aware of this?
    http://scienceblogs.com/stoat/2007/05/the_significance_of_5_year_tre.php#

    Comment by Hank Roberts — 22 Dec 2007 @ 10:31 PM

  193. Re # 190,191 Phil.Fenton and Wayne Davidson’s reponse to my comment (#189)

    I agree, while the -40C ice cube starts out warming at a faster rate (due to the greater temperature gradient, as predicted by Newton’s Law), its rate of warming will slow as the temperature gradient is reduced, and when it reaches -5C the other cube will have warmed closer to 0C – sort of a thermal version of Zeno’s Achilles and the Tortoise paradox. But, if you re-read my comment, you will see that I did not say the -40C cube will melt first; I was merely suggesting that the time to melting might not be as different as one might expect based on their starting temperatures.

    The converse experiment (which I have done) is to start with identical containers of warm water and cold water, put them in freezer, and see how long it takes them to freeze. Surprisingly, depending on the exact experimental conditions, the warmer water sometimes will freeze more quickly:
    http://math.ucr.edu/home/baez/physics/General/hot_water.html

    Comment by Chuck Booth — 22 Dec 2007 @ 10:36 PM

  194. Jim Cripwell writes:

    [[the other three sets, for all starting years 2001, 2002 and 2003 give negative slopes, meaning falling temperatures. It would seem that the NASA/GISS data is significantly different from the other three. It would also seem that the other three data sets indicate that world temperatures are falling in December 2007.]]

    So you used sample sizes of 6, 5 and 4 years, respectively, to derive your trends.

    Forgive me if I’m not impressed.

    Comment by Barton Paul Levenson — 23 Dec 2007 @ 7:07 AM

  195. Jim Cripwell, why don’t you just graph the derivative of the temperature vs time, and then you’ll have an instantaneous measure of what temperature is doing for each second! Uh, don’t bother to keep us posted on that, ‘kay?
    Jim, at a minimum you need to average over a full solar cycle to have any validity. Come on; get serious.

    Comment by Ray Ladbury — 23 Dec 2007 @ 8:05 AM

  196. Re #183: CW, Xavier Fettweis has some nice Greenland melt graphics, updated through 2006 and including some animations, on his research page. IIRC these are based on a different algorithm and data from Steffen. Xavier has a related paper here.

    Comment by Steve Bloom — 25 Dec 2007 @ 9:32 PM

  197. Could anybody suggest how I can find calculations for the warming effect of sea-ice loss. If, in September, Arctic sea-ice was 30% below the long-term average, how would one calculate the radiative forcings from the reduced albedo? Many thanks!

    Comment by Almuth Ernsting — 28 Dec 2007 @ 6:34 AM

  198. http://ice-glaces.ec.gc.ca/app/WsvPageDsp.cfm?id=11892&Lang=eng

    Check out the Quikscat animation on this page showing the progression of Arctic ice between Sept 7, 2007 and Jan 4, 2008.

    Correct me if I’m wrong, but this looks like a major loss of multiyear Arctic ice in last few months…

    When 2008 melt season begins, the increase in solar energy being absorbed by the Arctic Ocean will not be negligible.

    Comment by Bill Glenn — 26 Jan 2008 @ 8:12 PM

  199. According to Cyrosphere Today, it looks like the Arctic sea ice level has returned to within 200,000 square miles of the 1978-2000 mean.

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.jpg

    Specifically, there appears to have been many times in the 1980’s when the ice anomaly was less than it is now. Doe this satisfy condition C? (or at least exclude B and A?)

    Comment by erik gross — 4 Apr 2008 @ 2:55 PM

  200. Also, the southern hemisphere ice anomaly is hugely positive right now. (Far outside the 30 year history.) I know that it’s supposed to warm slowly down there, but this seems a little bit much. Any predictions on what the souther winter will bring?

    Comment by erikgross — 4 Apr 2008 @ 2:57 PM

  201. I am respectfully requesting some help here from scientists about a recent comment on the Dot Earth blog concerning the effects from the loss of Arctic sea ice.

    This was the comment (a sort of question-and-answer session with nonsensical answers from Sashka who you may have already seen here on realclimate):

    #
    73.
    May 9th,
    2008
    12:27 pm

    Re: #13 by John McCormick

    JM: What does all that open Arctic Ocean absorbing heat mean to the Western North American climate?

    S: It is absorbing in summer and losing during winter. But the answer is – almost nothing. Two reasons: (1) the area is very small; (2) the extra heat can much easier go up to outer space than laterally to midlatitudes.

    JM: Does anyone have any interest in climatalogical impact of sea ice melt or is it all about breaking records?

    S: Yes, this is what actually interests climate scientists.

    JM: We have a world of people reliant upon Western North American agricultural production which is reliant upon predicatable weather (precip and temperature).

    S: Climate change in Arctic will have negligible effect on agriculture and precisely zero on weather prediction.

    — Posted by Sashka

    This is a link to the nytimes page:

    http://dotearth.blogs.nytimes.com/2008/05/07/science-on-shrinking-north-pole-ice/#comments

    Thank you in advance for any help you can give.

    [Response: This appears to be referring to some recent work that indicates that disappearing summer sea ice affects Pacific storm tracks (making them go further north) and could affect rainfall in western North America. This is a relatively new result, and you’d want to see some replication in different models before you took this as gospel. It isn’t completely out of the bounds of possibility though. – gavin]

    Comment by Tenney Naumer — 9 May 2008 @ 1:56 PM

  202. OK, thanks, Gavin, I will see what I can find on that.

    Comment by Tenney Naumer — 9 May 2008 @ 4:03 PM

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