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skept.fr at 08:11 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Rob Painting : thanks for explanations, but '404 Error File Not Found' for the Lee 2011 reference. -
skept.fr at 08:06 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Lars #19 : Interesting. As you know, Lamb coined the terme ‘medieval warm period’ in his famous 1965 paper. Historical climatology, that is reconstruction of past climates by historical archives rather than physical or chemical proxy-based analysis, has known many evolution since the founding works in the 1960s, 1970s and 1980s. In particular, Lamb has been criticized by some researchers because of the scarcity of records, the poorness of their historiographic interpretation and the inherent difficulty of statistic extrapolations to large area. (A French book from a PhD thesis had been devoted to that re-evaluation of Lamb’s work, Alexandre P, 1987, Le climat au Moyen Âge, EHESS ; see also Hughes et Diaz 1994 for the re-analysis of previous MWP studies.) The story of Thorkel Farserk, cousin of Erik the Red, is typical of these uncertain records used in the first generation of historical climatology : one event in one season in one year, a possibly ‘pretyffied’ story (it has been suggested by Viking specialists that Erik the Red an co-founders were good propagandists for settlement in the new and ‘green’ land), etc. All that is too imprecise to infer a mean seasonal or annual temperature for whole Greenland, and of course for the whole Arctic circle (recall that we are speaking of sea-ice extent, not the Southern coast of Greenland). Anyway, it seems that Europe, and particularly Northern Europe, have known warm summer conditions one millenia ago. For example this work of Goosse et el 2006 ('al' including M. Mann) : ‘Proxy records and results of a three dimensional climate model show that European summer temperatures roughly a millennium ago were comparable to those of the last 25 years of the 20th century, supporting the existence of a summer “Medieval Warm Period” in Europe.’ -
Rob Painting at 07:26 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
skept.fr @ 15 - "Rob Painting #5 : the point is unclear for me. On this Mann MCA / present comparison, part of the North Atlantic basin seems warmer too during Medieval period, so isn't it sufficient for the advection of heat water you refer to?" I think you will notice that the reconstruction in Mann (2009) reveals a very localized patch of ocean warming in the North Atlantic. The overwhelming majority of the ocean during medieval times was cooler than the 1961-1990 baseline, especially the rest of the Atlantic. This is just consequence of the two very different processes operating between the two intervals. We know elevated CO2 levels were not responsible for the medieval climate, but today we have levels of atmospheric CO2 not seen for perhaps as long as 20 million years. This is crucial because elevated greenhouse gases, such as CO2, trap more heat in the ocean on a global scale. Therefore ocean heat content today is much higher than medieval times - there is simply more of it in the Atlantic today to melt the Arctic sea ice. Take a gander at Lee (2011) - What caused the significant increase in Atlantic Ocean heat content since the mid‐20th century?, particularly figure 1(a) and (b). As discussed in an earlier SkS post, the MWP seems to have been a re-organization of the global climate. Despite the localized warming aroung Greenland, the global mean background state was much cooler than today. -
scaddenp at 06:24 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
"WUWT claims that "during the peak of MWP glaciers were smaller than today"" Wouldnt apply to any Southern Hemisphere glacier that I am aware of. Of course LIA wasnt particularly pronounced in SH. -
Estiben at 05:22 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
TruthAtLast #18, Watch this, and try to pay attention. http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=385x275077 -
rcglinsk at 05:21 AM on 25 November 2011Correction to the True Cost of Coal Power - MMN11
"In fact, a recent Economics for Equity and Environment Network report concluded that the SCC in 2010 likely lies between $28 and $893 per ton, and will rise in 2050 to between $64 and $1,550 a ton." Wikipedia puts 2008 emissions at 29,888,121,000 tons. That times 893 is 26.7 trillion dollars. That doesn't seem plausible, it's around 40% of global GDP. -
Albatross at 05:04 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Truth @18, Hang on, I though it was a 60 year cycle? Or is that an 11 year cycle? Those who deny the reality and theory of AGW and try to wish away reality love to talk about cycles. In my post @17 I link to work by Fisher et al. (2011) that shows the ice caps in the Canadian Arctic are at their lowest levels in at least 4200 years. Is there a 4200 year cycle? I'm sure one could ferrit one out with enough curve fitting. Polyak et al. (2010) found that the sea ice extent in the Arctic basin is currently at its lowest levels in 2000 years. Is there a 2000 year cycle? And if these cycles are true, then the Arctic sea ice should start recovering any year now. but that is not what the data show, they show an accelerating rate of loss.
[Source]
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Philippe Chantreau at 05:04 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
TruthAtLast, why would you get your information from a political advocacy think tank? Singer and Avery are making a rather strained attempt at using D.O. events to try exculpate CO2, which is the only thing they ever try to do, in spite of all scientific evidence against the gas. I'm not sure what exactly the content of the whole book is and I will not waste my time on it. This has been discussed many times on SkS. There has not been a D.O. event in over 20K years. Their modern equivalent, Bond events show only loose correlation with climate changes; the last known Bond even is believed to have occurred approximately 1400 years ago. Since the postulated periodicity of the oscillation is 1470 yrs we should be due for one now. Note that these are Northern hemisphere cold events. Nice story Lars, how can we tell whether it's true? I tend to be skeptical by nature, especially of people bragging. -
Hyperactive Hydrologist at 05:03 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Lars, Interesting story, however I don't think historical anecdotal evidence and opinion is proof that the seas around Greenland were 4oC warmer than today. I think I'll stick to getting my information from Scientists. Also I think this guy might disagree with DR Pugh Ice Man. -
muoncounter at 05:02 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Lars#19: "it seems that the water must have been at least 4 °C warmer than this limit in the year in which Thorkel swam it" Yes, it would seem that particular day must have been unusually warm. Why would that one anecdotal incident have any bearing on annual averages and climate change? -
Lars Rosenberg at 04:36 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Here is a nice story from Hubert Lamb's ”Climate, History and the Modern World” (2nd ed 1995): ”For it is recorded in the Landnámabók, a book written in Iceland about 1125 cataloguing the settlement of Iceland a couple of centuries earlier and describing the Old Norse settlement of Greenland between AD 985 and 1000, that one of the first Greenland settlers, Thorkel Farserk, a cousin of Erik the Red who founded the colony, having no serviceable boat at hand, swam out across Hvalseyjarfjord to fetch a full-grown sheep from the island of Hvalsey and carry it home to entertain his cousin. The distance was well over two miles. Dr L.G.C.E.Pugh of the Medical Research Laboratories, Hampstead, has given his opinion, from studies of the endurance of Channel swimmers and others undertaking similar exploits, that 10 °C would be about the lowest temperature at which a strong person, even if fat, not specially trained for long-distance swimming, could swim the distance mentioned. As the average temperatures in the fjords of that coast in August in modern times have seldom exceeded 6 °C (+3 to +6 °C being more typical), it seems that the water must have been at least 4 °C warmer than this limit in the year in which Thorkel swam it and brought home his sheep.” -
Hyperactive Hydrologist at 04:29 AM on 25 November 2011Climategate 2.0: Denialists Serve Up Two-Year-Old Turkey
Blessthefall, I guess if you have been visiting this site since it's inception you will know that the CRU were cleared of any wrong doing no lees than 9 inquiries. You will also know that claims need to be backed up with evidence and your claim that the peer review process is corrupt requires such evidence.Response:[DB] HH, BtF's comment was moderated due to accusations of corruption, a Comments Policy violation.
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Bob Lacatena at 04:21 AM on 25 November 2011Climate sensitivity is low
245, Eric, 246, skywatcher, 247, Tom, I'd also point out that Lacis et al is dealing exclusively with fast feedbacks (like water vapor and clouds). As we are now seeing, things like the ice albedo feedback take a comparatively long time to develop, as would carbon feedbacks that result from methane release or major ecosystem changes. The point is, we are still, fortunately, talking about things in terms of a climate that could have a quick return to the old equilibrium if CO2 could somehow be drawn down. This will not necessarily be the case in the longer term, when those slower feedbacks begin to kick in, and so the reverse will consequently be just as slow (along with the fast feedbacks that go with the slow feedbacks instead of with the initial forcing). Beyond this, I am very, very concerned about how much CO2 the ocean has absorbed. In many past scenarios the ocean was the source of, not a damper on, added CO2. In this case the ocean is acting to hold down atmospheric CO2 levels by soaking up some of the excess. Even after we completely stop emitting CO2, where will it go? It can't go into the ocean, because it already is (and that is in balance). It has to go into biomatter, either on land or in the ocean, and in some way be sequestered, but the mechanics of it I would have to believe will take a very, very long time. And even after any part of it is drawn out of the atmosphere, the ocean will certainly respond by trying to maintain an equilibrium and so transfer it from the ocean to the atmosphere. If slow CO2 feedbacks involve things like the transition of huge swaths of the Amazon to savanna, or other ecosystems to desert, then this puts more CO2 into the atmosphere/ocean. But how does it then get back into biomatter? Temperatures must drop for rain forest or prairie to again take hold where savanna/desert has appeared, so that vegetation can then grow and put the carbon into other forms. But how does this happen until temperatures first drop? And how long will this reverse process take? The bottom line is that we're not getting anywhere near any of the fast-acting we-cut-atmospheric-CO2-back-to-285ppm scenarios any time soon, probably not for several hundreds of years, which will be more than long enough for us to see at least some if not many of the "slow feedbacks" take hold and therefore hard to reverse. [This with the understanding that "slow feedbacks" in past climate change events are going to be relatively fast in this case because we are pumping the CO2 into the atmosphere so abruptly and quickly as compared to increases due to most natural processes in the past.] -
TruthAtLast at 04:09 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
"Unprecedented melting in 1450 years--" am I the only one who recalls the 1500-year warming-cycle? http://www.ncpa.org/pub/st279 "The Earth currently is experiencing a warming trend, but there is scientific evidence that human activities have little to do with it. Instead, the warming seems to be part of a 1,500-year cycle (plus or minus 500 years) of moderate temperature swings."Response:[DB] "am I the only one who recalls the 1500-year warming-cycle?"
Apparently you're one who doesn't remember the debunking of that particular meme, here:
The prudent reader will take note of the source of "Truth"AtLast's linked blog piece, the National Center for Policy analysis, a Washington, DC-based "think tank", has produced such memorable pieces as:
How the Rise of Trendy Environmentalism is Harming the Environment
A Rough Week for Climate Change Myths
U.S. Press AWOL on Climate Skepticism
The spin is palpable; the "truth", lacking.
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caerbannog at 03:47 AM on 25 November 2011Climategate 2.0: Denialists Serve Up Two-Year-Old Turkey
Tom Curtis at 02:31 AM on 24 November, 2011 MarkR @19&20:1) There is a difference between auditing and replicating. The gold standard in science is that all results should be replicable, and results which are not replicable are considered suspect. To replicate a result, you design an identical or equivalent experiment, gather your own data, analyse them and publish the result. There is no need to have access to the original research's data in order to replicate the observations. The Met Offices (Hadley) and University of East Anglia (CRU) papers on global temperatures where clearly replicable based on the information released with their papers. I know that because their results have been replicated by NCDC, GISS, and most recently by BEST.
OK, so the long-sought-after CRU raw station data-set has been publicly available for about 4 months now. All of the raw data, metadata and documentation needed to replicate or audit the CRU's work are sitting on the CRU web-server, just begging to be downloaded and analyzed by the skeptic crowd. So, skeptics -- how's your auditing/replication work coming along? Haven't heard a peep from you guys since the CRU released all the data you'd been screaming for. As you should recall, the Muir Russel commission was able to validate via independent replication the CRU's work in just a couple of days. But here it is, 4 months after the data release, and we haven't seen anything (not even preliminary results) from you guys. What's the holdup? Did your dogs eat your laptops? I mean, it's not like you didn't have plenty of lead time to get your processing/analysis software in order. If you were really serious about checking the CRU's work, you would have gotten results out in just a day or two. BTW, I was able to validate the CRU results in a couple of hours after I downloaded the data. Just modified my simple gridding/averaging app to read in the CRU data/metadata format and ran the data through it. Not hard at all (The bulk of that two hours was spent debugging a stupid programming "thinko".) Here are my CRU results, plotted along with my GHCN raw data results and the official NASA land-temperature index results:
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Albatross at 03:37 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Chriscoz @3, "WUWT claims that "during the peak of MWP glaciers were smaller than today"" Well of course they would float that red herring. I'm not sure to which glaciers they are referring to. But as you say it does not apply to the Arctic. A new paper has also just been published on the Canadian Arctic glaciers by Fisher et al. (2011). They conclude: "Arctic ice core melt series (latitude range of 67 to 81 N) show the last quarter century has seen the highest melt in two millennia and The Holocene-long Agassiz melt record shows the last 25 years has the highest melt in 4200 years. The Agassiz melt rates since the middle 1990s resemble those of the early Holocene thermal maximum over 9000 years ago." Add to that the rapid loss of ice shelves in the Canadian Arctic that were buttressing glaciers, and we have quite the spate of bad news, and this is relatively early days of the Anthropocene. -
TruthAtLast at 03:31 AM on 25 November 2011The Debunking Handbook Part 3: The Overkill Backfire Effect
(-Snip-)Moderator Response:[DB] Off-topic snipped. Was warned about being OT here.
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Bob Lacatena at 03:27 AM on 25 November 2011Newcomers, Start Here
145, Tom Curtis, Tom, generally I think I would defer to you in most matters, because to me I generally learn more from your posts than I already know, a sign that you certainly know more and understand it in more detail than I do. That said, I'm not sure about a few things in your post. First, as a side note, I'm unsure exactly what you are saying was wrong in my post 143, since the topic of that response was the question of why H2O does not overwhelm the GHG contribution of CO2 in overlapping bands in the Earth's atmosphere, while your discussion reverted back to the previous question of why Mars, with more CO2, has a lower temperature. With that said, I think that I'm right in that the answer to the question that is the actual subject of 143 (H2O masking CO2, not the temperature profile of Mars) lies in the humidity profile of the Earth's atmosphere. Pertaining to Mars, I would take you to task to demonstrate the numbers that rate the various factors involved. Certainly I would think that the absence of large amounts of water vapor in the Martian atmosphere must be an important factor with respect to the actual temperature at the surface of the planet. Pressure broadening is certainly another important factor, but one that was complex enough that I shied away from including it in an explanation on a "Newcomers, Start Here" page. The atmospheric density issue is two fold -- partly due to the "heat absorptive" capabilities of an O2/N2 rich atmosphere which allow an individual CO2 molecule to actually absorb more IR by quickly transferring that energy to the surrounding air, and in that way relating the altitude of emission to the density of the atmosphere -- but also due to the simple expansion of the depth of the atmosphere and in this simpler way raising the altitude of effective temperature/radiation. But I'm not sure I've ever seen anything like hard numbers that would explain how important any of these factors are in proportion to the others. What would the overall temperature be like on Mars with H2O or on Earth without, or with more/less pressure broadening, or more/less non-GHG gasses? I'm not sure what the answer is, and while I know that pressure broadening is an important factor, I don't know that the lack of H2O (with a much broader spectrum of IR absorbance) isn't still the main factor. Do you have a source of hard numbers for any of this? I've tried looking through a few texts on planetary atmospheric physics, but without reading them in detail, I'm not getting any further on resolving this.Moderator Response: I, too, have failed to find a concise explanation accessible to a non-specialist. Maybe Ray Pierrehumbert can be convinced to contribute a post? -
skept.fr at 03:24 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Rob Painting : «In plain language, Mann's work suggested that current warming was likely due to mankind's carbon dioxide pollution, not any as-yet-unidentified, or yet-to-be-discovered or observed natural phenomenon» Beside the political hype, I suggest there are two debates in the Hockey Stick(s) : one is an immediate (often mediatic) interest for ‘record’, another is the scientific interest for natural variability (forced and unforced). That is to say : if you reconstruct a multicentennial variability in pre-industrial period with ±0,2K variation, it will not have the same implication for model that if you get a ±0,8 K variation (and that, whatever your variation for 1950-2010, very likely due to GHG). The second reconstruction would imply a higher sensitivity to forcings and/or a higher low frequency variation in the surface distribution of heat due to atmosphere-ocean coupling. I think modellers need to precise these points so as to refine detection-attribution studies or to better constrain their 'control runs' without anthropogenic forcing. At least, it is the way I interpret the most interesting part of this ‘controversy’... but maybe it is a bad interpretation! -
skept.fr at 02:51 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Concerning the Arctic zone, I recall some research suggested there could have been less or equivalent sea ice than now in the early Holocene, because of regional orbital forcing (for example this EOS 2006 paper ). But theses conditions have disappeared since mid-Holocene (for example Polyak 2010 conclusion : "This [recent modern period] ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities"). Rob Painting #5 : the point is unclear for me. On this Mann MCA / present comparison, part of the North Atlantic basin seems warmer too during Medieval period, so isn't it sufficient for the advection of heat water you refer to? -
shoyemore at 02:38 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
#11, Robert Way, The paper refers to snow temperature of Greenland only, not to the global average temperature. Unofortunately, the period you mention ~700 AD is outside the range generally considered to the be the Medieval Warm Period - that is taken to be 950-1150, a period when the snow temperature is shown to be about the same as the present. Viking settlement in Greenland began only after 900 AD, so these may not have had the advantage of a warmer climate usually assumed, and the "MWP" kinda vanishes. In fact, before the Vikings, Greenland had been settled by an Inuit-related people known as the Dorset people. Perhaps they left because of climate conditions, but that does not sound right for a Inuit-related better-adapted people than the Vikings. The paper is interesting and should repay further comparative study. However, it raises as many questions as it answers. -
DaneelOlivaw at 02:25 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
That's some dramatic graph. -
angliss at 02:16 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
I have a question - was the original figure in Monckton Pink or did you recreate it that way? ;) Happy Thanksgiving to all here who celebrate it.Response: [JC] It's the original colour. So "Monckton pink" is the official term for it now, is it? -
skept.fr at 02:00 AM on 25 November 2011Economic Growth and Climate Change Part 1 - Factors Influencing CO2 Emissions
perseus : "I doubt a 'zero' carbon economy will be as easy as you suggest. It will get progressively more difficult and expensive as renewable penetrations become higher, 'carbon leakage' becomes significant and we obtain diminishing returns from improving thermodynamic efficiencies further" Again, I agree with you. We all remember nuclear energy "too cheap to meter" and other unrealistic optimist projections, very usual in energy litterature since the XIXth century. Energy transitions are slower than we like to imagine, and that's true since the first wood to coal transition of industrial period. We can accelerate the pace by political will, but there are heavy constraints from the installed energy infrastructure and their socio-economic implications. Furthermore, electricity is just a small part of the problem because fossil fuel are also used for transport and heat, and they are uneasy to substitute in metallurgy, production of cement, plastic, glass, etc. Of course, scientists work on alternative solutions in all process, but the deal for a 450 ppm scenario is not just to replace a coal plant by a wind or solar farm. In last resort, such considerations also depend on the total energy production we aim, which itself depends on material quality of life and growth targets (your paper!). Humanity consume now approx. 500 EJ/year so, if you wish it consumes 250 EJ/year in 2050, it will be far more easy to achieve a zero carbon economy. But if you target 750 EJ/year at the same year, no hope with current technologies – we are not even sure there would be enough cheap fossil reserves to reach and sustain this level! Concerning "austerity" (we will probably discuss it with the 2nd part of the paper), the problem seems to me on first approach : who decide of the 'fair' level of individual, national or global austerity ? As we can observe in climate negociations rounds, it's as uneasy to convince emerging countries that they are already sufficiently "rich" as it is to convince rich populations policymakers that they must downsize their GDP for climatic reasons. And as we observe in everyday life, few people diminish spontaneously each year their carbon or energy footprint so as to divide it by 4 in 30 years. -
Paul D at 01:50 AM on 25 November 2011Climategate 2.0: Denialists Serve Up Two-Year-Old Turkey
I think the issue of whether publicly funded science should be open is more complicated. Sometimes governments fund research/science with the idea of selling the concepts to a commercial company later or sell the technology. If you made everything public, then such projects could not be sold off later. The other issue is national security. Indeed weather forecasting can be considered a military intelligence issue. Better forecasting can result in military advantage during conflict or used to predict the enemies actions. It can also be used in misinformation and counter intelligence. The issues are wide ranging and far from simple, so complete open access to publicly funded research is unlikely, only special cases such as climate science are likely to be published. -
robert way at 01:46 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Kevin C, It was warmer than present in Greenland during the MWP according to Kobashi et al. 2011 (includes Jason Box). Around 1100 AD it was warmer than present for most of a 50 year period and then around ~700 AD it was significantly warmer than present for ~100 years. (More than 1°C for most and 2°C warmer for a short period) (Nearly the difference from present to the LIA in Greenland).Response:[DB] An open copy may be found here:
http://www.leif.org/EOS/2011GL049444.pdf
Section 5.3 is relevant to this discussion.
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RickG at 01:43 AM on 25 November 2011Ice age predicted in the 70s
I just ran across this paper, (Damon & kunen 1976) "Global Cooling?" In the abstract is the following: Because of the rapid diffusion of CO2 molecules within the atmosphere, both hemispheres will be subject to warming due to the atmospheric (greenhouse) effect as the CO2 content of the atmosphere builds up from the combustion of fossil fuels. Because of the differential effects of the two major sources of atmospheric pollution, the CO2 greenhouse effect warming trend should first become evident in the Southern Hemisphere. The socioeconomic and political consequences of climate change are profound. Science 6 August 1976: Vol. 193 no. 4252 pp. 447-453 DOI: 10.1126/science.193.4252.447 Global Cooling? It seems that not only was the consensus recognizing global warming, but there was a warning with respect to socioeconomic and political consequences. -
Arkadiusz Semczyszak at 00:08 AM on 25 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
For me, work Kinnard (2011) only authorizes them to this conclusion: “Our reconstructed warming of ~2°C since the LIA matches the reported temperature increase of the Arctic Atlantic Water Layer (AAWL), obtained from observational data of the past ~120 years (21) (Fig. 3C). At present, there are no subcentennial-scale open ocean proxy data series available to document the temperature evolution of AAWL in the Arctic Ocean proper in the preceding two millennia.” and: “Although we cannot quantify from our data the variability of previous AW inflow to the Arctic by volume, our temperature data series and the above observational link suggest that the modern warm AW inflow (averaged over two to three decades) is anomalous and unique in the past 2000 years and not just the latest in a series of natural multidecadal oscillations.” And what of the “millennium oscillations”? Without these data (first citation) - how can so much speculation: "We know that the Arctic is the most sensitive region on the Earth when it comes to warming, but there has been some question about how unusual the current Arctic warming is compared to the natural variability of the last thousand years," said Marchitto, also an associate professor in CU-Boulder's geological sciences department. "We found that modern Fram Strait water temperatures are well outside the natural bounds." I think I wrote a clear and without errors ... -
Kevin C at 23:33 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Thanks Rob: That was the information I was after. AnotherBee: Thanks for clarifying the distinction between the mythical warm Greenland and the real one. The version in my head was much closer to the real one, but given how these myths propogate I should have been more precise in my question. So your comment was well made. -
Rob Painting at 23:21 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Arkadiusz Semczyszak - I know it's the language barrier, but I always find it hard to figure out what you're on about. But I'll have a stab at it. - Error bars. That's the large guava-coloured area in figure 1. Notice how it enlarges the further back in time one goes? - Kinnard (2011) state: "These results reinforce the assertion that sea ice is an active component of Arctic climate variability and that the recent decrease in summer Arctic sea ice is consistent with anthropogenically (human-caused) forced warming" - Kaufman (2009). Yup, orbital factors saw a decline in Arctic summer temperatures from the Holocene Climatic Optimum onwards, until humans started burning fossil fuels like crazy. Spielhagen (2011) state: "We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming." -
AnotherBee at 23:14 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Kevin C - I suspect that your recollection is wrong, or, at least, misleading. The narrative we remember for the Viking Greenland settlements goes "The Vikings farmed Greenland, therefore it must have been much warmer. Later the settlements got buried under glaciers." The first part of that is correct, but the rest of the narrative is wrong. They did farm, but they farmed in two settlements in limited coastal fringes, and it was worse-than-subsistence farming (because the farming and building eroded the fragile top-soil). The same sort of farming seems to have been possible for much of the intervening time, therefore the farming cannot be taken as direct evidence of warmer conditions. The Viking settlements did not get buried under glaciers (google Hvalsey Church). One got burried under wind-blown sand. Thus the failure of the settlements cannot be taken as direct evidence of cooler conditions. -
adelady at 22:56 PM on 24 November 2011Economic Growth and Climate Change Part 1 - Factors Influencing CO2 Emissions
perseus, one of the main reasons for the disproportion in male/female births is selective terminations. One of the main objectives of a focus on later family formation is that it actually requires a higher valuation of women's work and worth before general social and economic improvements. So instead of sitting back and waiting for better health and increasing prosperity to advance the causes of lower birth rates and improving women's status, you do the status and education first. And this always leads to better health for children and the community at large. Hey presto. Fewer children born further apart and all much healthier than before. There's at least one program working very well in Africa where the focus is on education for girls and later marriage for both men and women. One surprising outcome of this, then not so surprising when you think about it again, is that the boys are tremendously relieved that they don't have to take on the burdens of providing for a family as soon as they leave school. Everyone wins. -
Arkadiusz Semczyszak at 22:48 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
As usual: "shortcuts" (even for the post - definitely “too big”). If the authors in the abstract of their work they put such a statement : „... although extensive uncertainties remain, especially before the sixteenth century ...” It is worth mentioning … although. Of course, the authors mainly say that: „...both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years.” but they add that there are doubts - the margin of error. “... and may result from nonlinear feedbacks between sea ice and the Atlantic meridional overturning circulation. These results reinforce the assertion that sea ice is an active component of Arctic climate variability and that the recent decrease in summer Arctic sea ice is consistent with anthropogenically forced warming.” - write Kinnard et al. 2011. Granted, with the addition that this is not limited to: „recent decrease” and „anthropogenically forced warming.” Kaufman et al., 2009 argued that: in the period between 5600 and 3600 years BP (0 BP = calendar year 1950) energy flows in summer (JJA) at 65°N was reduced by 7.1 W • m-2 - demonstrating the fundamental role orbital factor in creating the natural decreasing trend in Arctic temperatures. The Earth now began to "orbit" closest to the Sun during the year in January - instead of in September as it did 7 thousand. years ago ... So for the past thousands of years in the summer months, gradually decreased the intensity of sunlight “arriving” at the Arctic. Summer Arctic became cooler at a rate of 0.2°C per thousand years. It should be noted however that this trend was many times interrupted for 200 years and even 400 years (by the trend positive) just through: „... nonlinear feedbacks between sea ice and the Atlantic meridional overturning circulation ...” - changes in amount of heat transported to the Arctic along Atlantic waters. We do not know precisely reasons for these historic natural disturbances. Spielhagen et al., 2011.: “Northward-flowing Atlantic Water is the major means of heat advection toward the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years.” "Disturbances" trend can be so natural, and the current unprecedented "disturbance" questionable. The Kaufman “unprecedented” - it was one of the biggest disputes in science in recent years.Response:[DB] The prudent reader will note that in this discussion of Arctic Sea Ice (being by definition at sea level) Arkadiusz introduces a common "skeptic trick"/technique of introducing data from a local ice core in Greenland to "muddy the waters". The issue, beyond the core data representing but a single geospacial location and thus by itself not representative of the whole (and much larger) region in which it resides, is that the core is near the Greenland summit (in order to get the deepest profile of the ice possible) and therefore at an elevation of over 2 miles above sea level.
Permissum lector caveo (let the reader beware)...
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Rob Painting at 22:24 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Kevin C - This global map is from Mann (2009) and is compared to a 1961-1990 baseline.
Much of the present summer sea ice retreat seems to be from warm Atlantic water moving into the Arctic and getting at the ice from below. There's simply much, much more warm water available in the Atlantic today. Both Kinnard (2011) and Spielhagen (2011) show this anomalous ocean warming.
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Kevin C at 22:01 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
Yes, I was surprised. I had it in my head that there was real evidence of Greenland being significantly warmer at some point during the MCA, although the effect was localised. Does this mean that it was sufficiently localised not to cover the arctic too, or is my recollection wrong? -
perseus at 21:51 PM on 24 November 2011Economic Growth and Climate Change Part 1 - Factors Influencing CO2 Emissions
Kevin I doubt a 'zero' carbon economy will be as easy as you suggest. It will get progressively more difficult and expensive as renewable penetrations become higher, 'carbon leakage' becomes significant and we obtain diminishing returns from improving thermodynamic efficiencies further. I fear that in placing all our eggs in the same environmental technology basket we risk the same over optimism as when we predicted 'cheap' nuclear energy, routine space flight and artificial intelligence. I'm not saying these won't happen eventually but we need to combat AGW now to avoid tipping points, and our best chance is to tackle it on several fronts. Good points in posts 4 and 5. However, austerity tends to be relative not absolute. We already have more than enough in the developed world. It is hardly unreasonable to expect people to avoid waste and excess and a great deal of our GDP is just that, it adds little of true value but creates environmental problems. Even the so called green technologies can generate pollution especially if it is done on the cheap: pollution casts shadow over Chinese solar rare earth metals technology boom Yes carbon is not the only issue, we live on a finite earth with limited resources and sinks, perhaps we also have a responsibility to other species as well and the more we consume the greater stress we place on these habitats. -
chriskoz at 21:50 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
WUWT claims that "during the peak of MWP glaciers were smaller than today" found here does not apply to arctic with very high certainty. Interesting to note, that on the graph above, arctic ice looks on average larger during peak WMP (1000-1300AD) rather than for LIA (1550-1850AD), although probably not statistically signifficant. Still, from that observation with counter-intuitive outcome, we can say that both MWP and LIA were local events while arctic ice could have enjoyed different conditions. -
bill4344 at 21:18 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
The BEST confirmations, Climategate 2.0 looking like a squib, and now yet another bloody Hockey Stick! Not looking to be such a festive season for some, is it? ;-) -
MA Rodger at 21:00 PM on 24 November 2011Arctic Sea Ice Hockey Stick: Melt Unprecedented in Last 1,450 years
The "Ice Hockey Stick." Startling stuff but are we truly surprised? -
CBDunkerson at 20:49 PM on 24 November 2011The Debunking Handbook Part 4: The Worldview Backfire Effect
Shibui, 'skeptics' seem to be able to believe just about any nonsensical thing... so sure, I suppose they could see the hockey stick as 'confirmation bias'. It just wouldn't make any sense given that it has been replicated by numerous studies, analyzed and confirmed by the NAS, and even matched by a few 'skeptic' analyses that set out to disprove it. All of which demonstrates the very opposite of confirmation bias, but that isn't going to stop 'skeptics' believing otherwise. -
Rob Painting at 20:00 PM on 24 November 2011Climategate 2.0: Denialists Serve Up Two-Year-Old Turkey
Tom Curtis @ 12 - that brings back memories. Is that now a "skeptic" training video? -
perseus at 19:25 PM on 24 November 2011Economic Growth and Climate Change Part 1 - Factors Influencing CO2 Emissions
Yes perhaps we should stick closer to the topic. Adelady. Yes there are other factors affecting population growth. In India the low proportion of females to males born is yet another, which will of course reduce population growth. However, it is notable that all of the methods if overdone could lead to social or economic instability in later years. -
Shibui at 19:08 PM on 24 November 2011The Debunking Handbook Part 4: The Worldview Backfire Effect
Don't John or Stephan feel that the Hockey Stick could be seen by sceptics as an example of Confirmation Bias? -
Tom Curtis at 17:58 PM on 24 November 2011Climate sensitivity is low
Eric (skeptic) @245, the rapidity with which a system adjusts to a new equilibrium depends not just on thermal inertia, but also on the magnitude of the disequilibrium. With the enhanced greenhouse effect, the disequilibrium is small, being approximately 1 W/m^2. This is because of both the small initial perturbation and the fact that the full effects of positive feedbacks are not felt until the system approaches the equilibrium temperature. In contrast, in the model analyzed by Lacis et al, the initial perturbation is around 30 W/m^2. Consequently the system adjusts towards equilibrium much faster because of the much larger disequilibrium. Even so, as skywatcher @246 points out, the system has still not reached equilibrium after 50 years. Further, Lacis et al state that they use the Q-flux ocean model with a 250 meter mixed layer depth. Had they used a model with deep diffusion, time to equilibrium would have been significantly extended (by a few centuries, I suspect), but the early changes of the system would have been unaffected. It just would have taken longer to close the last 0.1 W/m^2 of disequilibrium. -
skywatcher at 16:32 PM on 24 November 2011Climate sensitivity is low
Depends what you call equilibrium Eric - the temperature units on the Lacis diagram are pretty large, and it clearly hasn't reached perfect equilibrium even after >50 years. Why you suggest it supports a 10 year equilibrium mystifies me. From the diagram the change has reduced to being relatively slight after ~25 years, but equatorial regions are still cooling after 50 years. -
Tom Curtis at 15:22 PM on 24 November 2011Newcomers, Start Here
Eric (skeptic) @151, no it means it is a very weak positive feedback. By reducing the difference between polar and tropical temperatures it makes the escape of energy from Earth less efficient. Because the energy escape is less efficient, the global means surface temperature must be higher for the same amount of energy to escape. However, this effect is so small (for the temperature changes involved) that it is extremely dubious that it could be detected against background noise in the coming century. -
Eric (skeptic) at 15:19 PM on 24 November 2011Newcomers, Start Here
No, it's a positive feedback (less uneven -> less radiation -> more warming) -
Eric (skeptic) at 15:17 PM on 24 November 2011Newcomers, Start Here
Tom, you said "Bodies with very uneven temperatures radiate heat far more efficiently than bodies with very even temperatures." Does that mean that polar amplification (makes temperatures less uneven) is a negative feedback? -
Eric (skeptic) at 15:08 PM on 24 November 2011Climate sensitivity is low
A quote from the Climate-time-lag.html article: "How long does the climate take to return to equilibrium? The lag is a function of climate sensitivity. The more sensitive climate is, the longer the lag. Hansen 2005 estimates the climate lag time is between 25 to 50 years." While reading through Lacis et al regarding CO2 as a control knob, I noticed this diagram
Taking less than 10 years to cool to equilibrium suggests a short lag. That is for full removal of CO2, etc and I don't know if the time constant would be different for a change in CO2. But if the lag time is much shorter than the 25 to 50 years suggested above, then climate sensitivity is also lower than estimated by Hansen.
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Tom Curtis at 15:02 PM on 24 November 2011Newcomers, Start Here
Eric (skeptic) @146, yes, imthedragon's point @141 is correct, if easily misinterpreted. In the absence of an atmosphere and ocean to both retain heat due to their heat capacity, and to spread heat around due to the motion of winds and currents carrying heat from the tropics to the poles (and to a much lesser extent, from day side to night side, the Earth would suffer similar diurnal temperature variation to that encountered on the moon, ie, between -157 degrees C and 100 degrees C. Instead of that 257 degree C range, we have diurnal temperature ranges of between 5 and 30 degrees C (approximately), and that is almost entirely due to the capacity of the atmosphere and ocean to absorb and retain heat. What is more, that capacity also warms the Earth. Bodies with very uneven temperatures radiate heat far more efficiently than bodies with very even temperatures. For example, even though the effective temperature of the moon, ie, the temperature it would need to be to reradiate the energy absorbed from the sun to space if it was all one temperature, is around 380 degrees C, its blackbody temperature is actually 270 degrees C. The difference is due to the very uneven temperatures on the moon. However, this has nothing to do with the 33 degree C difference between Earth's effective temperature and its mean surface temperature. If the Earth was of uniform temperature with no greenhouse effect, its surface temperature would be 255 degrees K. As the Earth's temperature is not entirely even, it would actually be slightly lower than that, a fact often ignored for simplicity. But without the greenhouse effect, the surface temperature could not be raised above the effective temperature, let alone by the 33 plus degrees that it has been raised. So, yes, the atmosphere apart from the greenhouse effect makes the Earth's surface temperature stable. And yes, the greenhouse effect does nudge the temperature higher. But the 33 degree K (12%) nudge is more than just a bit, and indeed is absolutely crucial to the possibility of life on Earth.
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