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Comments 108601 to 108650:

  1. New temperature reconstruction vindicates ...
    People will have to pardon me if this is a silly question. Is there supposed to be something inherently profound about exactly what shape the hockey stick is? I keep getting this sense that Loehle is just pissed that Mann's original hockey stick graph was straight and he thinks it should have bends in it. He seems to go out of his way to try to make his own hockey stick (with hidden blade) as exaggeratedly bent as possible. But still, I keep coming back to the fact that what makes the hockey stick a hockey stick is the blade. Current warming. (We sure ain't playing Lacrosse here.) Loehle can tie the handle up in knots for all I care, it just seems to me that what is important is that current warming is unprecedented no matter how many crooks the handle has. Am I missing something?
  2. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    fydijkstra @22, You are making deductions using data over too short a period of time to be of statistical significance, and have not supported why you chose 2005. I could take those SL data (you should actually be using the data with both the inverse barometer correction, and with seasonal signal removed), and could argue that the rate of increase from 2007 until present is 3.3 mm/yr, which is above the long-term trend of +3.2 mm/yr. See the CSIRO site . So focusing on short-term trends does not make sense-- b/c the data are so noisy one can select short windows of time to support whatever point of view you wish to make. The CSIRO also state that: "This data has shown a more-or-less steady increase in Global Mean Sea Level (GMSL) of around 3.2 ± 0.4 mm/year over that period. This is more than 50% larger than the average value over the 20th century."
  3. The Phony War: Lies, Damn Lies and the IPCC
    archiesteel, the orbital forcing of the HCO ( fairly well understood and calculable ) gave some 50 W/m^2 more sunshine at the TOA for the Arctic during summer, and some 15 W/m^2 less sunshine TOA for the Arctic winter. Similar, though smaller changes also occurred at lower latitudes, including around 30 degrees North where the Mesopotamian settlements were founded. Knowledge of temperatures is all from proxy, and less certain than the solar orbital forcing which is pretty solid. Still, the Arctic is analyzed to have been significantly warmer during the HCO than it is today: Now, this pertains only to the Northern Hemisphere. But that's where the Mesopotamian civilization was. Interestingly, there was quite a bit of Arctic ice melt with this period, but not Greenland. (not the high interior anyway). Also, it is interesting that winters were colder and summers were hotter. Overall temperatures were somewhat higher (summers were disproportionately hotter). But imagine winters were a million degrees colder, and also summers were a million degrees hotter. The average annual anomaly would be zero. But it would be a deadly zero. Sometimes, the average doesn't much.
  4. New temperature reconstruction vindicates ...
    Ned, Good post! Way better than my comment on "Is the Hockey Stick Broken" but I do have some quibbles. You say: "It's worth noting that all the reconstructions show the Medieval Warm Period, the Little Ice Age, and 20th-century warming (though Loehle 2008 only runs through 1935)." This is clearly not the case as Mann's original Hockey Stick denied both the MWP and the LIA. [edit]
    Moderator Response: Insinuations of ill intentions are not welcome. Next time the entire post will be deleted.
  5. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    CBDunkerson: "One issue with the Wu analysis is that if significantly less ice has melted than previously thought then we have a bigger problem explaining the observed sea level rise. Any decrease in ice loss must be made up by increased expansion due to heating." The sea level rise can be explained very well from the gradual rise in temperature and the moderate ice loss from Greenland. Wu's suggestion that the Greenland ice loss is far less than was assumed so far is in perfect agreement with the fact, that there is no significant change in sea level rise. Contrary to popular claims the sea level rise is not accelerating. From 1993 to 2010 the sea level rose 2.7 mm/year. From 2005 to 2010 it was only 2 mm/year. These data can be checked here.
  6. Hockey stick is broken
    scaddenp & Co., With regard to Tamino, I have nothing to contribute to the discussion other than to say that I find "Climate Audit" more plausible than "Open Mind". The Tamino/McIntyre spat has turned into a cottage industry and good luck to both of them. Statisticians are like economists; if you put them all "End-to-End" they still won't reach agreement. The point I am trying to make is that if studies defy the historical record it is the studies that must be thrown out. Mann and his myriad supporters still insist that history be ignored but it is a battle they must ultimately lose. They should be ashamed for defending the indefensible. The post above and recent events support me. Take a look at Figure 1 that started it all. About 850 years with tiny variations and a very gentle decline followed by a rapid temperature rise. No sign of the MWP or LIA. Move on to Figure 2 that is almost identical to Figure 1. Shame on Wahl-Ammann! Still no sign of the MWP or LIA. The tiny variations are totally implausible when you consider the extreme weather events that occurred during the last 1,000 years such as the hot, dry summers around 1540 that caused major rivers in Europe to dry up. On the other extreme, the river Thames in London froze over on 24 occasions from 1408 to 1814. If you have not seen the following link before, enjoy! http://booty.org.uk/booty.weather/climate/1000_1099.htm Recently, the "Climate Science" community has begun to realize that their credibility has been ruined by historians so growing number of paleo-climate reconstructions show historical events as in Figure 6 (Mann 2008). Here, the MWP and LIA can be seen as minor excursions. What would happen if one left out the tree ring data? Here is a paper by Loehle with the answer: http://www.ncasi.org/publications/Detail.aspx?id=3025 This 2000 year reconstruction shows temperature excursions greater than 1 degree Kelvin and Medieval temperatures higher than 2010. Loehle has been demonized by establishment scientists such as Schmidt and Mann; nevertheless there are still folks like Ljungqvist who can produce similar results even with tree ring proxies included: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ljungqvist2010/ljungqvist2010.txt Climate science needs to stop muddying the waters by creating multi-proxy analyses that include even one proxy that fails the acid test of being consistent with history/archeology. Few if any tree ring proxies would survive and some other proxies might fail the cut too. The Ljungqvist paper covers 2000 years with decadal resolution using proxies located from 30N to 81N. It therefore covers the non-tropical northern hemisphere over recent historical times. The amplitude of temperature variations is 0.9 degrees compared to 3.3 degrees in Richard Alley's ice cores. However, global warming (or global cooling) should be much more pronounced at high latitudes (the central Greenland site was at 73N). When one overlays the temperature variations in Loehle 2007, Ljungqvist 2010 and Alley 2000 the historical features such as "Dark ages", MWP and LIA all show up in the right places so these analyses have some credibility, unlike MBH 98 et seq. apeescape, I read all those links (@43). Methinks they protest too much. Gavin in particular is beginning to sound a little desperate. He is paid to do what he does but he is not winning hearts or minds.
  7. New temperature reconstruction vindicates ...
    Robert Way writes: Isn't Moberg 2005 only NH? Argh, you're right of course. And while I could edit the text of the post, the "global" label is burned into the graphic of Figure 2. Well, I'll have to fix that... Anyway, thanks for pointing it out.
  8. New temperature reconstruction vindicates ...
    Zeke, looks like we had basically the same idea at the same time, right down to showing both land-only and land/ocean instrumental temperatures ... Although it looks like we used different approaches for centering the series. Zeke's lineup is more similar to Tamino's. This doesn't affect the amplitude of the reconstructions (e.g., the difference between the MPW peak and LIA trough) but it does make a difference in terms of comparison to current (instrumental) temperatures.
  9. New temperature reconstruction vindicates ...
    Rob, By Loehle making this rather bizarre statement he is placing the CA team in a rather awkward position. If CA audit Ljungqvist 2010 and find substantial errors which call into question the validity of Ljungqvist's analysis, then Loehle, by his own words, has not been vindicated. If the CA team audit Ljungqvist and find that the results stand, then others here and elsewhere have shown that Ljungqvist 2010 vindicates Mann and Moberg, not Loehle. In fact they show Loehle to be an outlier. What a pickle people sometimes get themselves into when they try and spin things. I can only imagine what a mess the thread is over at WUWT. One can only hope that some saner voices are trying to politely point out the huge problems with Loehle's assertion.
  10. The Asymmetric War on Climate Change: No Cause for Alarmism?
    doug_bostrom... That is pretty close, in which case, what was the public reaction to this report? Could this have anything to do with the real estate crisis? (Imagine a scam based on something this.) On the other hand, I remember hearing about the old man that lived on Mt. St. Helens, who just stayed there till it blew, and others that did not abandon the area until the very last minute, exhibiting how truely optimistic people can be, even with all kinds of warnings from scientists. Speaking of down the alley... you wouldnt be from the South Bay? Only asking per description of tragic accident you describe above...sounds very familiar.
  11. Billions of Blow Dryers: Some Missing Heat Returns to Haunt Us
    #50 NETDR at 04:10 AM on 29 September, 2010 we have had 1/3 of a doubling of CO2 No. Pre-industrial CO2 level is assumed to be 280 ppmv, while currently we are around 390 ppmv. log2(390/280) ~ 0.478 That is 47.8%, bit more than 1/3.
  12. New temperature reconstruction vindicates ...
    Very nice analysis, Ned!
  13. New temperature reconstruction vindicates ...
    It seems to me that Dr Loehle has committed a "high-sticking" foul in this hockey game. Albatross... (If I can allowed to mix my metaphors a bit.) Yes, I think they've got egg on their face but if you go over to the comments section there you find it's more than that. They're having a massive egg party! Egg is all over the place!
  14. New temperature reconstruction vindicates ...
    Zeke, excellent work as always. Kudos to Alden too. Rather than vindicating Loehle, it shows his reconstruction to be an outlier. This incident is (or should be) leaving Loehle and Watts with egg over their faces, again. Could someone in the know here please confirm whether or not M&M have actually put together or published a temperature reconstruction that could be compared with the above reconstructions? Thanks.
  15. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    The Rignot & Kanagaratnum paper cited in the OP is 2006, not 2007.
  16. New temperature reconstruction vindicates ...
    Beat me to it Ned! http://rankexploits.com/musings/2010/comparing-proxy-reconstructions/
  17. A detailed look at galactic cosmic rays
    Argus, it's *always* fortunate when there is empirical data against which we can test *any* theory. If his theory were correct, Svensmark would be fortunate that the data exists to confirm it.
  18. New temperature reconstruction vindicates ...
    Isn't Moberg 2005 only NH?
  19. New temperature reconstruction vindicates ...
    Good post, Ned. Wow - I'm amazed (or not) that Loehle has jumped on this as vindication. However, I believe that Loehle's temperature anomalies are relative to the mean of each entire series. This means that they are conveniently impossible to compare to recent instrumental temperature observations. So, I'm not sure that the Loehle dataset can be properly included included in Figure 2 here (maybe I’m missing something?). Basically, Loehle's reconstruction tells us what we already know - that temperatures were warmer 1000 years ago than 400 years ago. But he provides no real possibility to compare past temperatures to current values, although he seems happy to make speculative conclusions about the matter. Also RealClimate has a good discussion about many of the problems in Loehle's 2007 analysis. Ljungqvist's reconstructed temperatures are relative to the same base period as the HadCRU instrumental temps. For what it's worth, Figure 1 by Ned is easy to recreate and clearly shows that Ljungqvist's reconstruction is in agreement with the conclusion that recent temperatures are anomalously high compared the last thousand years (I was actually working on this before I read this post – Tamino got me interested): -Alden
  20. Billions of Blow Dryers: Some Missing Heat Returns to Haunt Us
    So far the warming has been far below the 6 ° C rate the scientists want to use for a doubling of CO2. Since we have had 1/3 of a doubling of CO2 we should have had more than 2 ° C warming we haven’t had this. [.7 ° C is the accepted value and less than ½ of that is from CO2 in the best case.] . To get around this scientists have speculated that the ”missing heat” is stored in the oceans ! The problem is that since 2005 both atmosphere and the ocean have been cooling. . http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ . Some have SPECULATED that the missing heat may be in the deep parts of the ocean but since they haven’t measured to test this speculation they don’t know. This article claims to have found 20 % of it. . The most important and ignored part of the missing heat controversy is when the heat will return. ? The surface area of the ocean is several orders of magnitude greater than the slight polar warming the article seems to find. When will the missing heat return to the surface where it can cause substantial warming ? . Since we are only speculating where the heat has gone and have only speculation about how it got there how can we predict how long it will be until it returns ? Answer: We can’t ! We have a theory of CAGW which DEPENDS upon the “missing heat ” returning in the next 100 years and we don’t know where the heat is and don’t know if or when it will return. Since we cannot find it we cannot measure it so we don’t know much of it exists. . Despite all of this “the debate is over” and we should throw ten’s of trillions of dollars at the nearest politician to make it go away.
  21. New temperature reconstruction vindicates ...
    The most extended while reasonably calm and polite (by general blog standards) discussion of M&W I've seen is at DeepClimate M&W seems a variation of "post in haste, repent at leisure." There is some discussion here at Skeptical Science, on the Is the hockey stick broken thread.
  22. New temperature reconstruction vindicates ...
    I haven't had the time to really delve into M&W. I see a lot of discussion of it elsewhere. We should probably have a post about it here.
  23. New temperature reconstruction vindicates ...
    Ned, Have you thought about including M&M2005 and/or M&W2010 for comparison? Much to my surprise, I have not been able to find a figure for M&M's temperature reconstruction. Did they even produce one which could be compared with the above?
  24. New temperature reconstruction vindicates ...
    Doug writes: That's an useful analysis pulled together in a very short time, Ned. Thank you, Doug. I hope this will not turn out to be a case of "post in haste, repent at leisure" ...
  25. New temperature reconstruction vindicates ...
    Albatross, here's what Ljunqvist says about recent temperatures in the paper: The temperature since AD 1990 is, however, possibly higher than during any previous time in the past two millennia if we look at the CRUTEM3+HadSST2 90–30°N instrumental temperature data (Brohan et al. 2006; Rayner et al. 2006) spliced to the proxy reconstruction. The proxy reconstruction itself does not show such an unprecedented warming but we must consider that only a few records used in the reconstruction extend into the 1990s. Nevertheless, a very cautious interpretation of the level of warmth since AD 1990 compared to that of the peak warming during the Roman Warm Period and the Medieval Warm Period is strongly suggested.
  26. New temperature reconstruction vindicates ...
    Between this and the Tamino item, looks as though vindication is forestalled indefinitely. That's an useful analysis pulled together in a very short time, Ned.
  27. New temperature reconstruction vindicates ...
    Ljungqvist's reconstruction vindicates Mann and Moberg of course, but that has not stopped Loehle from spinning this paper. So currently NH land-surface temperatures (as per CRU) are about 1 C warmer than they were during the much touted MWP. That is impressive Fantastic post Ned! Thanks.
  28. 2010 Climate Change Resource Roundup
    Skeptical Science is "...not 'peer-reviewed science'? I suppose one could say that Steven Goddard is reviewed by his peers. Still, that remark sort of stands out as unselfconscious.
  29. New temperature reconstruction vindicates ...
    For a rather different take on this issue, see today's post by Tamino.
  30. The Asymmetric War on Climate Change: No Cause for Alarmism?
    RSVP here's an example of the output of the kind of thinking you mention: Climate Change in Coastal Areas in Florida: Sea Level Rise Estimation and Economic Analysis to Year 2080 The bulge of our wallets is a constant fascination. The study above takes a stab at looking at effects of climate change on individual taxpayer wallets as opposed to corporate balance sheets, seems down the alley you speak of.
  31. 2010 Climate Change Resource Roundup
    doug_bostrom "Does anyone have any estimates of how warm September currently is. " I track the UAH Channel 5 daily values here. The final final UAH monthly value is close to the monthly Channel 5 average, but not the same. The Channel 5 September,2010 data is the highest in the UAH data series, so I expect Sept to be another warm month.
  32. The Asymmetric War on Climate Change: No Cause for Alarmism?
    Before going on, it might be of interest to baseline what would be considered an acceptable public reaction to global warming. Assume a hypothetical situation where "the public" got a perfectly accurate account of global warming with timetables for temperature increase in every location on Earth for the next century including an exact description of how the coastlines will be affected, etc. Currently, people have to pay to dredge boat harbors. I am sure some people would be happy about knowing such details. What would be the best real estate options, etc. But, you need details, not some blank statement about how the "planet" is warming. At any rate, all this points to being in control, which is what its all about.
  33. Billions of Blow Dryers: Some Missing Heat Returns to Haunt Us
    TimTheToolMan is correct that it's overreach (I think, no coffee here yet) for me to convey the impression of P&J's results as crisply explaining the slackening of upper ocean heat uptake in the past few years. However, TimTheToolMan is unambiguously wrong with his remark, "What they've done is extrapolated constant warming over the 20-30 year period of the data beyond that which it was actually measured." In a nutshell, what P&J did was to resample an array of stations covering a vast territory, finding a statistically significant warming broadly encompassing the majority of stations in the interval between samples. That's not an "extrapolation of constant warming," it's a notation that deep ocean heat content in the areas surveyed has increased during the sampling interval. Failing TTTM's explaining errors in P&J's methods and then offering an improved result, he's offering an ineffective means of saying "I doubt it" using a few more words. After that, TTTM's argument goes farther downhill, into the abyss: "The research doesn't ACTUALLY show warming at all. It assumes it." This sort of desperation usually indicates the goring of a sacred ox. BP, here's what the authors have to say about geothermal flux: The local abyssal heating rates outside of the Southern Ocean (Fig. 8a) are comparable to geothermal heating, typically 0.05 W m–2 away from ridge crests, which can have a significant impact on abyssal ocean circulation and water properties (Joyce et al. 1986; Adcroft et al. 2001). However, if the ocean circulation and geothermal heat fluxes are in steady state, this heating should not cause trends in abyssal temperatures. 30 But, if the abyssal circulation were to slow, geothermal influences might contribute to a change in abyssal temperatures and even circulation." BP's remark begs the question (presuming for a moment that some or all of this signal were down to geothermal flux), what would cause abyssal circulation to slow? See Kouketsu, Masuda. The paper really is a model of circumspection in the technical sense of the word, an education if you follow the citations.
  34. Hockey stick is broken
    I second that, scaddenp, I'd also like to know what historical variations in climate Mann's (or any of the many other multi-proxy reconstructions) disagree with. So far as I'm aware, most areas in which events such as the MWP or LIA are recorded historically, show these events in their proxy records. It is areas elsewhere in the world (actually, by far most of the rest of the world), which don't necessarily show the same variations. Are you the blinkered one, not grasping the implications of that, GC? Do you believe that all climate variations are spatially and temporally uniform? I'd like to see you support the accusation of Mann using only a few Yamal trees with some evidence, givent he latest paper used over a thousand proxies from a worldwide network, from many different kinds of proxies. Such accusations of cherry-picking have been debunked over and over again, not least by the multiple independent studies with different methodologies showing largely the same results.
  35. The Phony War: Lies, Damn Lies and the IPCC
    @CW: "The CRU and GISS trends are at or below the best estimate for the "most optimistic scenario" for the period you prefer." Both are within the margin of error, therefore confirming the trend. "They are below the most optimistic scenario for the subsequent MSU era." Irrelevant. "And not surprisingly, no I am not "concerned" about the recent warming rates." Of course not. "1. The same rate occurred in the CRU without modern CO2 forcing ( CRU and HadSST 1.7 K per century from 1910 to 1945 ). So such a 35 year trend is not even a record in the global thermometer era." That's not a logical argument. Just because something happened before doesn't mean the current situation isn't alarming - especially since, according to all other factors, we should be in a cooling phase right now. Seems to me your opposition is mainly political in nature. "2. During the Holocene Climatic Optimum, climate was actually much more extreme: (longer, hotter summers -and- longer colder winters). But this was the period of the founding of human civilization!" Do you have references for you claim that the climate was more extreme during the Climate Optimum. Also, it seems as though current global average temperatures are *higher* than at the Climate Optimum. That alone should be cause for concern.
  36. The Big Picture (2010 version)
    Perhaps we should move this discussion to How sensitive is our climate? We're well off topic here...
    Moderator Response: Yes, everybody, please do.
  37. The Big Picture (2010 version)
    Given that the various empirical climate sensitivity estimates include volcanic aerosols, Milankovitch redistributions, seasonal irradiation, and the 11 year solar cycle, I think there's plenty of data there on different kinds of forcings. Water vapor and clouds act as feedbacks on other forcings; if the temperature of the atmosphere changes, we should see regional feedbacks in a matter of days at most. In fact, given the speed of water vapor feedback, we should see your postulated large negative feedback on a seasonal basis (summer/winter) - and we don't. Unless you have evidence/papers indicating fractal vapor distribution changes over the seasons that induce large negative feedback on seasonal temperature changes??? Regarding glacial estimates and uncertainties, I am much more interested in papers such as Tung 2007; calculating 2.3 to 4.1°C based on the 11-year solar cycle (i.e., what happens when deviating from current conditions), Hoffert 1992, who looked at reconstructions for both colder and warmer periods, est. 2.3 +/- 0.9 °C, and Bender 2010, response to Mount Pinatubo aerosols, 1.7 to 4.1°C. I agree that glacial ice coverage introduces additional effects - hence my preference for estimates that don't include glacial periods. And again, your postulated large negative feedback is not seen.
  38. The Phony War: Lies, Damn Lies and the IPCC
    Ned, it is the IPCC that predicts the 0.2 C per decade rate that should be occurring now. And it is the IPCC that predicts the various warming rates for different 'scenarios'. Science is about predictions of theories and the following observations which reject or modify the theories. It is incorrect to state that all the models show acceleration. In fact, in the IPCC graph, only one scenario indicates even a slight acceleration, that being the A2 (red). The 'middle' scenario, the A1B, indicates a DEceleration of temperature trend. So does the 'most optimistic' scenario, the B1(blue). And all observed temperature trends are at or below the 'most optimistic' scenario!
    Moderator Response: please limit image size to 400. Thank you.
  39. The Phony War: Lies, Damn Lies and the IPCC
    archiesteel, The CRU and GISS trends are at or below the best estimate for the "most optimistic scenario" for the period you prefer. They are below the most optimistic scenario for the subsequent MSU era. And not surprisingly, no I am not "concerned" about the recent warming rates. Why? 1. The same rate occurred in the CRU without modern CO2 forcing ( CRU and HadSST 1.7 K per century from 1910 to 1945 ). So such a 35 year trend is not even a record in the global thermometer era. 2. During the Holocene Climatic Optimum, climate was actually much more extreme: (longer, hotter summers -and- longer colder winters). But this was the period of the founding of human civilization!
  40. The Big Picture (2010 version)
    You can see climate variability during glacial times is huge compared to its present day value. This variability also implies a much higher sensitivity. Therefore paleo climate sensitivity values derived from glacial epochs have to be scaled down considerably to be applicable today.
  41. Billions of Blow Dryers: Some Missing Heat Returns to Haunt Us
    @TimTheToolMan: absence of evidence is not evidence of absence. What the article is about is the fact that the deep ocean *is* warming, which indicates there's lots of room for the "missing heat" to hide, and thus it is erroneous to claim OHC has not increased since 2005.
  42. The Big Picture (2010 version)
    #134 I wrote: "Modeled and empirical evidence indicates that the actual climate sensitivity is ~3°C for a doubling of CO2 or an equivalent radiological forcing." - see How sensitive is our climate? I see. Climate sensitivity is at leas 3°C (Lorius 1990), but not more than 2.3°C (Tung 2007). Fine. The science is settled. Seriously. As I have already mentioned multiple times, not all "forcings" are created equal. They act at different parts of the climate system (soot: snow covered surface, CO2: upper troposphere to stratosphere) and influence different processes (SW absorption vs. LW emission). Sensitivity of average surface temperature can be radically different for such agents, even if their magnitude converted to the common currency of energy flux anomaly happens to be the same. Also, regional distribution of climate response also varies widely depending on the particular kind of forcing applied. With paleoclimatic studies it is a bit more difficult. It is quite easy to see that general climate sensitivity should be higher in a world where permanent continental ice caps reach down to 40N than in our present day setup. Therefore "climate sensitivity" does not only depend on the kind of forcing but also on structural aspects of the climate system, changing themselves slowly over geologic times (as mountain ranges, configuration of continents, oceanic currents, presence or lack of ice sheets, etc.)
  43. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    I agree with some posting here that the results from Wu et al. should be included. With that said, as Cynicus pointed out @12, nowhere in their paper do Wu et al. speak to the rate of change of loss with time (i.e., acceleration or a slow down), they talk about the mean loss between 2002 and 2008. Wu et al. do confirm recent studies which found that the once thought to be stable EAIS may be losing ice (albeit with large error bars). They also confirm that Alaska Yukon are lost about 100 Gt a year between 2002 and 2008-- that is about as much as the loss from GIS, or as much loss as EAIS and WAIS combined. Also, there is a note of caution required. From a summary of the Wu et al. paper by Bromwich and Nicolas(2010): "However, the revised estimates of glacial isostatic adjustment carry their own uncertainties: they depend strongly on a small number of GPS records that are all located on the ice-sheet margins." So, the jury is still out as someone else here has noted ...in the mean time the data indicate that GIS, WAIS and EAIS continue to lose ice mass, very likely at an accelerating rate.
  44. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    Here's a screen grab from the paper that suggests the mechanism controlling mass loss for SE Greenland glacier. ( http://i51.tinypic.com/2wqvkab.png ) This got me thinking whether it's sensible to produce a whole Greenland mass loss and then try to attribute this to a single forcing? As Kahn 2010 paper suggests NW Greenland acceleration in mass loss began in 2005. The Murray 2010 paper suggests SE Greenland accelerated early 2000's and then the rate declined late 2000's. I assume acceleration in SW Greenland began in early 2000's but I don't know how it then developed. Let's ignore what's going on in the NE. If we have multiple different processes occuring at different times in different regions of Greenland over the past decade can we lump the results from these different processes into a single whole Greenland ice mass loss and get any real meaning from that? (BTW Murray et al 2010 suggest the above mechanism as the main process controlling mass loss in SE Greenland.)
  45. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    As part of the Arctic Report Card Hanna, Box and Huybrechts (2008) summarized the mass balance state of the Greenland Ice Sheet. The mass balance has been assessed using multiple measures only one of which is GRACE. Reading this report card will indicate that the bulk of the studies are closer to the Wu et al., (2010) results discussed above. Ten years ago we could not assess the mass balance of the ice sheet. Today we are still developing this skill. As usual it is best to rely on multiple data sets. We have laser altimetry, surface mass balance models and GRACE. A couple of sentences from the aforementioned authors ..." A recent survey concludes that the GrIS is currently losing ~100 Gt yr-1 (Shepherd and Wingham 2007). However, there remains considerable discrepancy among these pioneering observational estimates. " and "Airborne and satellite laser-altimetry data analyses indicate a volume loss of about 60 km3 yr-1 in the 1993/4 - 1998/9 period, that increased to about 80 km3 yr-1 in 1997-2003 (Krabill et al. 2004, Thomas et al. 2006). Various recent analyses of gravimetric (GRACE) satellite data suggest greater mass (volume) losses in the 101-226 Gt yr-1 (111-248 km3 yr-1) range within the recent few years, that is, 2002-2006 (Luthcke et al. 2006, Velicogna and Wahr 2006). " The time periods and methods are not identical but do indicate that the low 100 Gt yr-1 has been a frequent result. It is evident that the loss has not stopped, as the volume losses of Humboldt, Jakobshavns, Petermann and many others continued in 2010
  46. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    I think a lot of people have been talking about the Wu et al. 2010 paper with respect to these Greenland estimates. A newer paper (Bamber and Riva, 2010) was recently published and included an estimate for both ice sheets. I submitted a comment on the paper asking why the authors chose to go with Van Den Broeke's (2009) estimate rather than the Wu et al (2010) estimate. The Bamber and Riva Paper can be accessed here: http://www.the-cryosphere-discuss.net/4/1593/2010/tcd-4-1593-2010.pdf Their reply is listed here: http://www.the-cryosphere-discuss.net/4/C813/2010/tcd-4-C813-2010.pdf Some highlights of the reply include: "Because a paper is the most recent does not, necessarily, make it the most reliable or "best" estimate." "It is important to realise that they are producing a global solution for GIA and PDMT by finding a least squares minimisation for the GRACE, GPS and modelled OBP data sets. The solution has not been tuned for any one location and the quality of the solution will depend on the quality and spatial density of the data sets that went into it. As far as we can tell, the solution is not constrained to pass through the observations. In Greenland, there are very few GPS site with a sufficiently long record (just 3) that could be used and none in the interior of either Antarctica or Greenland." Bamber and Riva are both very well known glaciologists and Bamber is well-known as being a world leading glaciologist. One of the best, therefore we should take his estimates quite seriously. What I think the take home message is that Wu et al (2010) use a new approach to calculate Greenland mass balance. This approach may become the best approach in the near future when more GPS stations are available (IPY put up a lot) but that currently this approach (although novel and useful) is not accurate enough to be termed the "best" estimate for Greenland Ice Losses. I have identified quite a few issues myself with the Wu et al (2010) paper that are not big but that require maybe some questioning. I think that a lot of people have to watch out how quickly they jump on the bandwagon of a new paper. Funny how well reported the Wu et al (2010) paper was compared to Bamber and Riva (2010) which is newer...
  47. The Big Picture (2010 version)
    BP, Riccardo, KR Excellent discussion gentlemen. This WV-Cloud-CO2 interaction is the nub of the whole AGW hypothesis. I have followed BP's arguments through many months and many threads, and a constant theme is that the WV and ice albedo feedbacks are not as positive as claimed and therefore the 'greenhouse' insulating effect of the atmospheric column is lower. Dr Trenberth puts the WV and ice albedo feedback at about +2.1W/sq.m - would anyone like to update this figure? I don't profess to fully understand how this energy flux number relates to temperature differential across the column or how the 'fractal' nature of clouds as seen from space affects the average IR emitting temperature of the Earth which is quoted at about 255degK. BP's response on the paleo data argument would also be very interesting.
  48. French translation of the Scientific Guide to 'Skeptics Handbook'
    Having recently returned from a trip to the South of France, I would like to make the following comment about this translation : Très bon !
  49. The Big Picture (2010 version)
    Berényi - You missed half of my statement, and a very important half: I wrote: "Modeled and empirical evidence indicates that the actual climate sensitivity is ~3°C for a doubling of CO2 or an equivalent radiological forcing." - see How sensitive is our climate? Not just models, but multiple sets of paleo data and analyses indicate about 3°C climate sensitivity. The empirical evidence shows it quite clearly; we don't have the large negative feedback you are postulating. And as I have stated before, if the evidence contradicts your hypothesis, you need a new hypothesis. Claiming "we can't know, so what about this theory!" is a variation of the Appeal To Complexity; a bad argument.
  50. Is Greenland losing ice? (psst, the answer is yes, at an accelerating rate)
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, F03026, 15 PP., 2010 doi:10.1029/2009JF001522 Ocean regulation hypothesis for glacier dynamics in southeast Greenland and implications for ice sheet mass changes. T. Murray et al I recommend a read of the above paper if you can get past the paywall. It proposes a slightly more complex process controlling glaciers in SE Greenland. They even dare to suggest re-advancing glaciers in this region in the late 2000's.

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