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Comments 89651 to 89700:

89651. logicman at 06:25 AM on 8 April 2011
       Arctic Ice March 2011
       Gilles: I can clearly discern the trend of your comments and they extrapolate to an infinity of 'yes buts' and a miniscularity of useful content. Our planet doesn't care what we believe. It just keeps on swinging around that jolly old sun whether or not the human race has wiped itself out. Once the Arctic is perennially ice free the unstable northern climate will do something which we cannot yet predict with any certainty. At the extremes of that range of uncertainty are two highly plausible scenarios: 1 - methane clathrates dump their cargo into the atmosphere , triggering massive global temperature rises. 2 - a warmer Arctic causes greater precipitation of snow which no longer melts entirely in summer. Within a decade or two it becomes obvious that a new ice age has started. This is not science fiction and it is not a computer game. I write about climate change because I wish the human race to continue long after I am gone. I shall pass this way but once. If I can leave behind me even the tiniest amount of scientific knowledge that is of value to future generations then I shall not have lived in vain.
89652. Nicholas Christie-Blick at 06:00 AM on 8 April 2011
       Skeptical Science in other media
       48% of Americans think that "the seriousness of global warming is generally exaggerated, up from 41% in 2009 and 31% in 1997, when Gallup first asked the question" (Gallup, March 11, 2010). 40% of Americans say that "God created human beings pretty much in their present form at one time within the last 10,000 years or so]" (Gallup, December 10-12, 2010). An additional 38% think that "Human beings have developed over millions of years from less advanced forms of life, but God guided this process. That leaves fewer than 22% of Americans whose views on evolution as a phenomenon even remotely resemble our scientific understanding. I do not think that either demographic group can be dismissed as fringe. They represent mainstream American thinking. And that is a problem.
89653. daniel maris at 05:56 AM on 8 April 2011
       A Plan for 100% Energy from Wind, Water, and Solar by 2050
       I agree with CBD. The techologies are now proven. Storage is a problem but even that is capable of resolution. Really, the problems, in so far as they exist are cost-related. And really it is an infrastructure issue. We are faced with the sorts of costs associated with putting in place a motorway network or rail network, of that order. But once in place renewables are nearly all very cheap to run - wind, solar, tidal, hydro. Storage carries a lot of cost admittedly but it is not so much as to put a renewables solution beyond our grasp. We can deploy a range of renewables solutions: hydro, compressed air, methane production, hydrogen production, chemical batteries, molten salts... Look at what Germany is doing - making rapid progress towards 20% solar (7GW installed last year). Look at Denmark - nearly at 20% wind energy. Scotland is on target to reach 50% electricity generated by renewables from 2020. I think a 100% solution within 20 years is doable if we have the political will. Perhaps we need to find in the UK something like $60billion (this is a fairly wild guesstimate on my part). $3 billion a year. It's not a huge, huge sum in terms of our GDP. It is doable I believe. Of course if we paid for the infrastructure completely out of taxation, in later years we would still be generating income from the infrastucture which would offset the investment (or - to put it another way, a large part of your elec bill already goes into funding infrastructure investment).
89654. Gilles at 05:56 AM on 8 April 2011
       Arctic Ice March 2011
       DB: I think the number of words and topics I'm adressing is much less than yours - so how to qualify your own modus operandi ? muoncounter : it may be that the Arctic will be icefree in 2030. I don't know. What I'm discussing here is the significance of a trend - and so the possibility of extrapolating it. I know that any decreasing trend can be extrapolated to zero. What does it prove ?
       Moderator Response: [Dikran Marsupial] It doesn't prove anything, but it suggests that based on the information we have, unless something changes, we are likely to see an ice free Arctic. That interpretation is so obvious, I am surprised it needs explaining to you. You do know that you can never prove an hypothesis empirically, only disprove, don't you? Also the difference between your posts and DBs is that his goal here evidently is to discuss the science, unlike you, which explains why his posts generally have useful content. Enough sniping.
89655. muoncounter at 05:28 AM on 8 April 2011
       Arctic Ice March 2011
       GIlles#186: "what is the variability at this frequency (i.e. : at a 30 years scale)" Based on the graph you posted in #158 and others (myself included) have also posted, the 'variability' is thus: Within 30 years, summer Arctic sea ice extent may be perilously close to zero. The JAXA monthly extent data show this 'variability': summer minimum has dropped by one third, from ~6 million to ~4 million sqkm, in less than a decade. It is remarkable that one who claims such powerful scientific credentials either cannot or will not see this. What can be said of a decade hence? < 2 million sq km? < 1 million? Yet you persist with nonsensical questions. 'And Nero fiddled whilst Rome burned' will be rewritten to say 'And Gilles prevaricated whilst the summer Arctic became ice free.'
89656. Dr. Jay Cadbury, phd. at 05:22 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Couldn't it be argued that since the last 40 million year were dominated by cooling, with the past 10,500 mostly warming, the trend has not really reversed because it would take at least that many years of warming to claim the trend has been reversed?
       Moderator Response: [DB] The majority of your comment is off-topic here. Please use the search function to find a more relevant thread if you wish to pursue getting an answer to this. If anyone wants to reply to this appropriately, please do it on the relevant thread with a pointer here. Thanks!
89657. actually thoughtful at 04:50 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Or, the accurate version: "There were 6 times as many papers predicting warming as there were cooling from 1965-1979."
89658. actually thoughtful at 04:49 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Once upon a time there was a list of one line responses to each skeptic argument on this site. For the life of me I can't find it today. I suggest the following as the one line response: "There were 9 times as many papers predicting warming as there were cooling from 1965-1979"
       Moderator Response: [DB] See http://www.skepticalscience.com/oneliners.php.
89659. Gilles at 04:41 AM on 8 April 2011
       Arctic Ice March 2011
       Mucounter :"A quick count shows at least 12 prior threads about Arctic ice loss (including Greenland, but excluding Antarctica). And yet there are still those who claim to disagree on the most basic points: Arctic summer ice extent is decreasing at an increasing rate and Arctic temperatures are increasing. " Mucounter : when I said that a variation must be estimated with respect to the noise, I'm not saying the variation does not exist. You're just stating that the variation exists, and I don't disagree on that. It was not my point. My point is : what is the variability at this frequency (i.e. : at a 30 years scale). Do we have an accurate measurement of it, yes or no ? ( - Snip - )
       Moderator Response: [DB] Off-topic portion snipped.
89660. pbjamm at 04:28 AM on 8 April 2011
       Arctic Ice March 2011
       This discussion has been interesting and educational, so thanks to all who participated. At his point though I am having difficulty following what Gilles is arguing for/against. Perhaps a restatement of your position is in order? It might clear some things up and get this discussion back on track. At the moment it seems to be all over the place and getting a bit personal.
       Moderator Response: [DB] Gilles' modus operandi, after having watched his orbit over at RC and here for over a year, is to draw as many possible people into as many conversations as they will endure for as long they can stand; in doing so, he will say less with more words than can be believed for the sole purpose of wasting your time.
89661. Albatross at 04:14 AM on 8 April 2011
       Arctic Ice March 2011
       Readers, Global warming refers to the increase in the globe's mean temperature; warming, will not be uniform across the planet, nor will it be monotonic. For example, the theory of AGW suggested for a very long time now that the northern high latitudes will warm faster than elsewhere with increasing GHG concentrations. And that is exactly what we are seeing, and not surprisingly, the ice volume is decreasing fastest in the northern high latitudes. This is all quite elementary and simple, and very well documented in the scientific literature, as are previous natural mechanisms responsible for the advance and retreat of the ice caps, yet some choose to ignore the science (and history) and choose instead to talk through their hats and troll. The trolling has now lost its entertainment value and is now boring and tiresome. This thread really needs to be cleaned up.
89662. muoncounter at 04:12 AM on 8 April 2011
       Arctic Ice March 2011
       Gilles#169: "It's a pity that we loose so much time on so simple things" For the first time, we agree! A quick count shows at least 12 prior threads about Arctic ice loss (including Greenland, but excluding Antarctica). And yet there are still those who claim to disagree on the most basic points: Arctic summer ice extent is decreasing at an increasing rate and Arctic temperatures are increasing. I suggest that anyone who claims to have 'scientific' objections must first review the mountain of data presented in these many threads; if they still have something to say other than 'I can't see the correlation' or 'No, its not,' then we can talk.
89663. Albatross at 04:04 AM on 8 April 2011
       Arctic Ice March 2011
       RE long term variability in the Arctic temperatures and sea ice, please read the links(e.g., Polyak et al.) posted in my post @38. The long term downward trend and acceleration of Arctic ice volume loss that is being witnessed in the Arctic is clearly highly unusual and not explained by natural variability alone.
89664. Gilles at 03:54 AM on 8 April 2011
       Arctic Ice March 2011
       " It is clear that ice extent began to decline around the 1850s. Prior to the 1850s the eastern coast of Greenland was virtually unapproachable due to the many miles of landfast ice extending from Nord to Kap Farvel and beyond." Very interesting, but frankly, I'm lost : didn't you say that the ice melting didn't occur before ? if there is long term (secular) variability and short term (annual) variability, what about the medium term (decadal) variability ?
       Moderator Response: [Dikran Marsupial] If you think someone has contradicted themselves, give a link to the previous comment so that it can be verified. Without it, this looks very much like trolling, the ice has waxed and waned for millenia, so it is very unlikely that any such comment was made.
89665. meh at 03:54 AM on 8 April 2011
       Call for beta testers of the latest SkS Firefox Add-on
       Unfortunately, FF4 does not think it is a compatible plugin.
       Response: Is that the "official" older version or the new beta version?
89666. Bob Lacatena at 03:50 AM on 8 April 2011
       Arctic Ice March 2011
       178, Gilles,

       It is not obvious at all for me , sorry. Do you have a correlation between summer extent as a function of winter volume ?

       I have told you repeatedly that looking for simplistic correlations and focusing on correlations without understanding physical mechanisms is a waste of time. But you know that, don't you?

       I don't see what you have explained...

       Of course you don't, because admitting to any aspect of global warming is contrary to your belief system.

       Again the first decade of the XXIth century when ice most retreated is far from being the decade when temperatures most increased.

       This is patently and demonstrably false and misleading. First, what matters here are Arctic, not global, temperatures, as I demonstrated in the graphs that you are conveniently ignoring. Second, the pace of continued warming from 2000-2010 is not nearly as important as the temperature which as been reached by that point, as well as what logicman keeps referencing, which is basically that a "tipping point" has now been reached which is freeing methods for old ice to pass out of the Arctic circle. It's basically a different paradigm than past centuries presented. Before, all that mattered was temperatures, melting the ice inward from the edges. Now, wind and water circulation patterns are becoming important, because the ice further inward has thinned and melted enough to free up. Of course, if one can't think beyond a pair of centuries long graphs, taking into account physical mechanisms and varying observations, instead of the most childishly simplistic views of things... well, you're just never going to get it.
89667. DSL at 03:50 AM on 8 April 2011
       Models are unreliable
       Ggf, I have a problem with your prediction that the warming will not exist or won't be bad. And I have a problem with your support of political action that prevents attempts to mitigate. And you must admit: your modeling is much less robust than the IPCC's. Seriously: upon what basis do you contradict not only the models (which try to tell us "how much when") but their foundational science (which tells us "what")? If you don't have a problem with the science, then you are forced to say, "It's going to happen." At that point, it would be damnable to say, "but we don't need to worry about when, because models of fluid, dynamic conditions are somewhat inaccurate." If you do have a problem with the science, then take it to the appropriate thread. Perhaps we can apply the same argument to the human climate. Politicians and governments, after all, are modelers of dynamic, fluid situations that, even worse, do not have stable structures, laws, etc. We should just give it up: no government! Oh wait . . . sigh.
89668. Marco at 03:43 AM on 8 April 2011
       Has sea level rise accelerated since 1880?
       Charlie A, please note Neil White's comment at Tamino http://tamino.wordpress.com/2011/03/31/so-what/#comment-49986. It's quite relevant to your comment (and an "ouch" for Houston & Dean).
89669. Gilles at 03:31 AM on 8 April 2011
       Arctic Ice March 2011
       sorry for unclosed boldface tag
89670. Gilles at 03:30 AM on 8 April 2011
       Arctic Ice March 2011
       concerning proxy : I didn't refer to the instrumental curve, but to the proxy reconstruction. Please read again my post "another related question : do you have a physical explanation of why the arctic sea ice extent doesn't show any significative variation in the 1900-1940 period, when the average global temperature shows a variation similar , although slightly smaller, to the current one ? and when, noticeably , proxies data show the maximal variation ? are boreal trees much more sensitive to some kind of temperatures that sea ice doesn't feel, and reciprocally? " so I think having clearly stated that 1) instrumental temperatures increased in both periods, a little bit more in the second than in the first (but not by orders of magnitudes) 2) proxies increased mostly in the first period 3) Arctic ice decreased mostly in the second one. Do you agree, or not? is there an obvious explanation for these weird correlations, showing that the temperature increase was mostly correlated with proxies but not with ice in the first period, but the opposite in the second one ? I could suggest one actually : there is a "good warming" , which is natural and can't do any harm to nature, in the first part of the century. The good warming likes trees because trees are natural, and likes polar bears too. So it doesn't make sea ice melt , but it helps trees growing. And there is a "bad warming", human-made, which does the opposite because it doesn't like Nature : makes sea ice melt and does not help tree growth Sphericae : " Please point to any one post of yours in the past year when you have demonstrated complete agreement with some aspect of current climate science." It was not the point, and I didn't claim that either. I don't see the interest to post if I have no question to solve about science. I don't ask things about relativity either. "Please point to any one post of yours in the past year when you've not taken that position on any issue." All posts : I didn't say everything was cyclical. I said that the significance of a variation must be estimated by the comparison with natural variability in a previous period. "Winter ice extent recovers close to 100%, but it is an illusion, because the ice is thin so the summer extent depends on winter volume as spring/summer temperatures, not winter extent or winter temperatures. Since the two are entirely separate, of course there's no correlation between the two. I think this is pretty obvious to everyone, so why do you bring it up?" It is not obvious at all for me , sorry. Do you have a correlation between summer extent as a function of winter volume ? "I think that pretty decisively explains why we're seeing retreating extent now and not earlier in the century," I don't see what you have explained - just drawing two curves and saying "oh they have both risen" is very far from an explanation. Again the first decade of the XXIth century when ice most retreated is far from being the decade when temperatures most increased.
       Moderator Response: Fixed broken bold tags [Dikran Marsupial] The "good warming" "bad warming" appears to be blatant trolling, I suggest this post is ignored. Also nobody here is suggesting a correlation bewteen two graphs is an explanation, it is a correllation that corroborates an explanation.
89671. logicman at 03:24 AM on 8 April 2011
       Arctic Ice March 2011
       Once again, I am grateful for all comments. The ongoing debate here has helped me to realize that I need to compile a list of all known or suspected sea-ice melt feedbacks, positive and negative. Let me correct some misunderstandings. We have maps and reports going back to the Elizabethan era which, together with many proxy studies, help us to determine the extent of ice prior to the 1950s. It is clear that ice extent began to decline around the 1850s. Prior to the 1850s the eastern coast of Greenland was virtually unapproachable due to the many miles of landfast ice extending from Nord to Kap Farvel and beyond. Baffin Bay had perennial ice which blocked access to the entrance to Nares Strait and the NWP except for 2 to 4 weeks in the year. North Baffin Bay was discovered by William Baffin in 1616 but his discovery was not believed for 2 centuries because the ice prevented any access until then. The history of discovery in the Arctic is a history of reduced total ice mass. Prior to about 1850 the Marginal Ice Zone - MIZ - would melt in summer and return in winter. Since about 1850, more ice has melted in summer on average than has reformed in winter. The discrepancy has been increasing, with a notable acceleration post 1950 and another post 1990. Contrary to popular belief the MIZ does not consist only of new ice. As new ice was advected into the main pack, to circulate and age there, older ice would advect out into the MIZ. Along the coasts of Greenland the MIZ also contains a very substantial number of icebergs. MIZ compressed into coasts continues to age. MIZ advected through Fram Strait leads to a loss of old ice. What has been changing is the total area covered by sea ice and the circulation patterns. As the main pack has shrunk and the MIZ has followed it, a point has - in my opinion - long been reached where the MIZ and the main pack were equal in extent. Judging by the 2010 and current fragmentation patterns, and the loss of multi-year ice, the main pack now has the consistency of the former MIZ. In plainer language: I fear that the Arctic's sea-ice cap is almost all MIZ - hence subject to substantial seasonal loss. Fragmented ice presents substantial open water to be heated by the sun. The warm water is advected under the ice promoting bottom melt. That bottom-melt feedback is in addition to the feedback due to the loss of albedo. I'll halt there for now, for fear that this comment might grow into an entire article. :)
89672. NewYorkJ at 03:20 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       what Alexandre said...
89673. dana1981 at 03:15 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Thanks all. By the way, the study mentioned by citizen in #1 is Peterson 2008 - the study whose data is plotted in Figure 1. Albatross #3 - Schneider mentions in his book that he's taken a lot of heat for Rasool and Schneider (1971) over the years, mainly from politicians and bloggers. Keen #5 - I have little doubt that Christy is well aware of at least most of the information in this post. The term "lying by omission" comes to mind when thinking about his testimony.
89674. arch stanton at 02:58 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       bibasir, I agree. I'll post a review after I read it.
89675. Charlie A at 02:57 AM on 8 April 2011
       Has sea level rise accelerated since 1880?
       The headpost by Tamino asks about Houston and Dean "Why do they repeatedly drone on about “deceleration” when the average of the acceleration rates they measure, even for their extremely limited and restricted sample, isn’t statistically significant?" The answer is given in their paper. Looking at acceleration allows one to ignore glacial isostatic adjustments, which are one of the biggest unknowns when looking at sea level. Houston and Dean looked at tide gauge levels that did not have GIA applied. This can be done since it is a reasonable assumption that the isostatic rebound adjustments do not change over the less than 100 year period they studied.
89676. KeenOn350 at 02:53 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Nice post - very simple - you would think Christy could understand it!
89677. Ggf9191 at 02:47 AM on 8 April 2011
       Models are unreliable
       Logicman The fluid mechanics analogy is a poor one. This is a much simpler system and the computational tasks involved here and the data collection required to produce usefull results is trivial compared to the data capture or computational difficulty in modeling global weather systems. Also the results produced by computer models can be tested in wind tunnels with clay models or prototypes to validate the results. We don't have the luxury of these things when modeling the global climate. I do not have a problem with using models to enhance or understanding of what is happening which is essentially what the fluid mechanics models are used for. But I am very concerned when countries set emmissions targets on the basis of climate models and politicians believe that achieving these targets will avert disasters that are predicted by the same models. This is suspension of disbelief on a massive scale.
89678. logicman at 02:42 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       I second that "beautifully done". It's hard to argue with that chart - but I doubt that will keep the usual suspects from trying. :)
89679. trunkmonkey at 02:40 AM on 8 April 2011
       Climate's changed before
       Indulging in a little attitude I find efforts to cast the PETM as a paleo fossil fuel burning event caused by the rifting of Greenland from North America utterly preposterous, right up there with the giant gymnosperms rototilling the Ordovician soils to foster weathering and beds of gravel preventing pre-Wisconsin ice sheets from attaining any thickness! One can readily observe from weather satellites that no great billows of smoke are coming from the current rifting in the Red Sea-Gulf of Aden-African zone, nor in the Gulf of California, all fossil fuel rich areas. Furthermore, the rifting of Greenland away from North America and Eurasia was well underway at the end of the Cretaceous.
89680. Albatross at 02:18 AM on 8 April 2011
       Christy Crock #1: 1970s Cooling
       Beautifully done. Oddly, I was unaware of Rasool and Schneider (1971) until reading this. Very interesting.
89681. Nicholas Christie-Blick at 02:10 AM on 8 April 2011
       Skeptical Science in other media
       One more for 'adelady': There is no conflict between science and religion in one of two senses: 1) if one sets out consciously not to accept propositions that are demonstrably untrue; or 2) if one fudges - perhaps along the lines of 'god intended it that way'. The difficulty in the first case is that even the existence of god makes no sense in light of what we know about natural phenomena, at least any god remotely like that conceived by contemporary religions. The second case can be illustrated by the Roman Catholic stance on evolution. Officially, the church accepts evolution as a historical description. However, the idea that it and we specifically were planned from the outset has nothing whatsoever to do with any scientific understanding of how evolution occurs. The church's position therefore is a fudge that diffuses debate but misrepresents the science. John Cook is best advised to stick with the science of climate change.
89682. Albatross at 01:34 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       Bibasir, Sadly Tea Party types have been bragging online about ow they go to Amazon and give poor reviews on liberal books. I assume that is now also applicable to climate science books. Have no fear, others who have actually read the book will soon post rational reviews based on the content, not on ideology.
89683. Alexandre at 01:32 AM on 8 April 2011
       Arctic Ice March 2011
       Sphaerica at 01:03 AM on 8 April, 2011 OT: It looks like the imageshack pics can only be seen when you log in to their website (at least to me). Apparently, this problem is only solved when John makes a duplicate of the pic in his website and redirects the link, which is not feasible in blog posts. Only so that you know.
       Moderator Response: [DB] If others cannot see Sphaerica's graphics, let me know & I will fix it.
89684. Albatross at 01:29 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       Earth: The Operator’s Manual is a very exciting project, and I very much look forward to reading the book and watching the series. Here is a challenge to all here. So far I have emailed the ETOM URL to 9 academics across North America (and one in Africa), as well as someone associated with an NGO. A very modest tally, so it should be easy to beat. I also plan on emailing it to members of parliament. Come on SkS readers, let us spread the word. Do I hear a 20?
89685. Alexandre at 01:21 AM on 8 April 2011
       Call for beta testers of the latest SkS Firefox Add-on
       I'd like to test it too. Please send me one, John.
       Response: Sent, thanks
89686. CBDunkerson at 01:17 AM on 8 April 2011
       Arctic Ice March 2011
       Moderator on #172. Right, allow me to rephrase: I made statements about actual Arctic temperature anomalies shown in the Kaufman graph (which showed both actual and proxy values) attached to post #158. In #169 Gilles suggested that this indicated I 'can't really read a figure' and used a new Kaufman graph, showing only proxy values, to 'refute' my numbers. I do not find this argument compelling.
       Moderator Response: [Dikran Marsupial] Once pointed out, neither did I. However this thread seems in need of more moderation than most [which is why I have had to withdraw from active discussion], and removing some of the heat from the discussion will encourage a more rapid return to scientific issues. So please can we all stick ultra-strictly to the comments policy.
89687. Bob Lacatena at 01:03 AM on 8 April 2011
       Arctic Ice March 2011
       171, Gilles,

       could you please show me a post where I said there was no Global warming ?

       Please point to any one post of yours in the past year when you have demonstrated complete agreement with some aspect of current climate science.

       ...could you please show me a post where I said that "everything" was either random or cyclical ?

       Please point to any one post of yours in the past year when you've not taken that position on any issue.

       winter extent and summer extent are poorly correlated

       Irrelevant and a good example of your constant obfuscation. This is exactly my point, that there is no correlation between the two. Winter ice extent recovers close to 100%, but it is an illusion, because the ice is thin so the summer extent depends on winter volume as spring/summer temperatures, not winter extent or winter temperatures. Since the two are entirely separate, of course there's no correlation between the two. I think this is pretty obvious to everyone, so why do you bring it up?

       just try to correlate the variation of sea ice extent or area and the variation of average temperature of the Earth, and show me the correlation.

       Again, science isn't done only by correlation, but by hypothesis, experiment, and confirmation or refutation. The hypothesis is that warming temperatures will reduce summer ice extent through the mechanisms described. Observations show global temperatures increasing and summer ice extent retreating, completely in line with the hypothesis. Look at your own graph in post 158. See how the temperatures spike up? And the ice extent spikes down? That is called a correlation. To get more specific, however, while viewed from a distance global temperatures appear to have risen consistently over the past century, in fact the increase in the past 3 decades has been markedly higher. More importantly, the distribution is not even. Warming at the poles is much greater in the past three decades, particularly in spring. Consider: 1940-1950 spring warming by latitude (note the scale, not the curve alone): 2000-2010 spring warming by latitude (more than double 1940-1950): 1940-1950 summer warming by latitude (note that the north pole actually demonstrated cooling!): 2000-2010 summer warming by latitude (note that while warming is less, exactly as expected by GHG theory, it is still positive rather than negative): I think that pretty decisively explains why we're seeing retreating extent now and not earlier in the century, despite apparent global warming (but not necessarily significant polar warming) over the entire period.
89688. bibasir at 00:58 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       Someone needs to post a review on Amazon. There is only one review with a short paragraph of denier points. I ordered the book and will post a review after I read it.
89689. Albatross at 00:56 AM on 8 April 2011
       Arctic Ice March 2011
       RE the melting of sea ice, and claims that it melts from below. It can melt from above and below, and melt ponds are a mechanism by which the surface albedo is lowered, leading to a positive feedback process for melting. From NSIDC: "Sea ice melts during the summer when solar radiation heats the ice surface.....After the snow starts to melt, melt ponds form, and because water has a lower albedo than snow, the surface albedo of sea ice with snow and melt ponds drops to about 0.75 (75% solar radiation reflected). As the melt ponds grow and deepen, the albedo continues to decrease, leading to higher absorption of solar radiation and an increased rate of melting. Energy to melt ice can come from sources besides direct solar energy. Water that is under the ice and that has a temperature above the freezing point causes the bottom surface of the ice to melt. Warm surface waters cause the edges of the ice to melt, particularly in leads and polynyas." [Satellite-derived surface temperature trends for 1981-2003 Source Earth Observatory] [from Earth Observatory] From EO link: "The maps also show that, in most areas, the date of freeze onset is changing more than the date of melt onset. The scientists say this pattern is consistent with a climate process known as the ice-albedo feedback. Dark ocean water absorbs more sunlight than bright, reflective ice. Even a small change in the start of the melt season exposes the ocean to more incoming sunlight, which warms the water, which melts more ice, and so on. The more solar energy the ocean absorbs during the summer, the longer it takes in the fall for the water to cool down enough to freeze." Arctic SST anomalies: [Source NSIDC] From above NSIDC link: "The high sea surrface temperatures resulted largely from the loss of sea ice: dark open water areas absorb more solar radiation than reflective ice. The warmer water in turn helps to melt more sea ice. This positive feedback likely contributed to the ice loss through summer 2010, especially late in the season when surface melt had largely ceased."
89690. CBDunkerson at 00:44 AM on 8 April 2011
       Arctic Ice March 2011
       Gilles: "Can't you really read a figure ?" I can read the part where the first graph had both proxy and actual temperatures while the second includes only the proxies. [snip] >plonk<
       Moderator Response: [Dikran Marsupial] Please no accusations of duplicity. It is best to apply Hanlon's razor, in such circumstances. I have edited rather than deleted as the scientific point is a good one (unless Gilles can provide a reason why we should trust a proxy reconstructions over direct observations).
89691. Daniel Bailey at 00:34 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       His "Greatest Knob" talk can be found here, for the interested. Off-topic, but inspired, is another talk by the selfsame Alley which shows his genius at communication. The Yooper
89692. Alexandre at 00:02 AM on 8 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       I'm an Alley fan since I came across his "Greatest Knob" lecture on the net. He's quite a character, really charismatic. It's the kind of outreach this issue needs. I'll definetly watch it.
89693. KR at 23:57 PM on 7 April 2011
       Upcoming book: Climate Change Denial by Haydn Washington and John Cook
       h pierce - Replacement fuels are "pie in the sky"? An interesting statement, but I think the facts contradict it. For example: I've been following Swift Enterprises progress in that regard. They are working on a biomass fuel to replace 100LL gasoline for small, prop driven planes in the US and around the world. The fuel appears fully functional as a replacement, economical to produce (competitive pricing), without added leading (required by the 15-60 year old engine designs in many private planes). It's currently undergoing testing towards certification as a legal replacement. It does, apparently, smell like old sweat socks, but that's the only drawback I've heard of yet. This is a good place for such developments - start in a limited market with higher prices (since 100LL is a tiny fraction of production), bootstrap up from there. And Swift isn't the only company in the business.
89694. Arkadiusz Semczyszak at 23:37 PM on 7 April 2011
       Has sea level rise accelerated since 1880?
       Absolutely no denying the negative impact of raising the sea level, but I would like to post a few remarks. At the beginning of some “Sisyphean” working. @Tom Curtis Be very careful in interpreting the sea level during the Eemian. Another - the greater was the weight of the glaciers in the NH continents during the glaciation preceding the Eemian - another "post-glacial rebound”. In addition: “This may have been due to the fact that a large part of the ice sheet that today covers the western part of Antarctica did not yet exist.” “In the northern hemisphere, insolation was much higher than today during the summer months, and much lower during the winter ones, making seasonal contrasts much more acute.” (ibidem). Are also disputed the average global temperature Eemian - could be a more than 1-2 degrees C - more than - on average - in the twentieth century. Is the current rate of sea level rise - “what’s the big deal?” Looking at the Holocene - we can say: “During this ~5000 year period of high sea level, growth hiatuses in oyster beds and tubeworms and lower elevations of coral microatolls are interpreted to represent short-lived oscillations in sea-level of up to 1 m during two intervals, beginning c. 4800 and 3000 cal yr BP. The rates of sea level rise and fall (1–2 mm yr-1) during these centennial-scale oscillations are comparable with current rates of sea-level rise.” ... and the future (based on an understanding of the past)? - a problem to a separate discussion. I recommend especially the last sentence: ... "that there is much about interpreting the geologic record of sea-level variation that we still do not understand. (...)."
       Moderator Response: [DB] And I especially like this sentence from earlier in your last linked source: "it could have risen quite quickly, as much as 2 meters per century, says geochemist and lead author Jeffrey Dorale". You assume SLR will be linear while your last linked source shows that it most likely was not. Hansen 2011 speaks to nonlinear destabilization of the ice sheets, with multiple meters of SLR occurring globally as a result. It may not be what you want to read, but the true skeptical mind considers more than just that which supports their position, to avoid confirmation bias.
89695. Gilles at 23:35 PM on 7 April 2011
       Arctic Ice March 2011
       "Your position (No Global Warming):" could you please show me a post where I said there was no Global warming ? "Everything is either random or cyclical" could you please show me a post where I said that "everything" was either random or cyclical ? "We can't know anything" do you think we know everything ? [Discussion of scientific background snipped] "Ice melts from above due to warmer air Ice melts from below due to warmer water" I admit that ice rarely melts because it's getting colder. "Less ice refreezes over winter, so the depth is less, although the extent is the same" first winter extent and summer extent are poorly correlated. Second all the peripheric ice is one year old, as I said - so the depth doesn't vary much in the outer parts. I will not comment all the other sentences : just try to correlate the variation of sea ice extent or area and the variation of average temperature of the Earth, and show me the correlation. and again, how much of your comments does belong to the category of "ad hominem " comments ?
       Moderator Response: [DB] Please look up the definition of "ad hominem". [Dikran Marsupial] I have already warned you that discussion of your science background is irrelevant and off-topic, I have snipped it this time, next time I will just delete the post.
89696. DSL at 23:32 PM on 7 April 2011
       Human CO2 is a tiny % of CO2 emissions
       Aye, Tri1cky--but the thing is that we're not going to be able to do anything about it until we've convinced the people who run the democracies that we are the problem. We are the problem. We're dumping massive CO2 into the atmosphere. Want to solve the problem? Stop dumping massive CO2 into the atmosphere. Or find a way that allows the CO2 to be taken out of the atmosphere at the rate it's being dumped (or slightly greater). There are threads for habitability here, here, and here.
89697. Bob Lacatena at 23:23 PM on 7 April 2011
       Arctic Ice March 2011
       Gilles,

       .... could you explain the big difference in the post-1900 behavior of these two curves ?

       Yes, because the warming at the poles in the past 30 years has been dramatically greater than during the 1900-1940 period (by GISTEMP, roughly 1.7˚C versus 0.7˚C). Look, this is very simple. Your position (No Global Warming):
       • Everything is either random or cyclical
       • We can't know anything
       • You are a scientist
       Science's position (Global Warming):
       • Ice melts from above due to warmer air
       • Ice melts from below due to warmer water
       • Less ice refreezes over winter, so the depth is less, although the extent is the same
       • Thinner ice melts faster
       • Summer ice extent has been dropping at an accelerating rate since the onset of serious global warming
       • Temperatures keep rising so each year the ice melts sooner
       • Open ocean absorbs more heat than ice, providing a positive feedback (i.e. warming the planet further)
       • You are a random/cyclical voice that repeatedly posts tiresome denial talking points at SS and RC, flavoring them with just enough detail and scientific language to give them an air of knowledge and superiority, while simply ignoring anything that anyone says that you can't easily obfuscate, or that exposes your obfuscation for what it is.
       • Because you ignore the points you can't obfuscate, but throw together huge diatribes where obfuscation is easy, you pollute entire threads with what appears to be reasonable debate, but is really merely part of your ongoing, unending effort to confuse the people for whom the facts behind any issue are not already painfully clear.
89698. Gilles at 23:19 PM on 7 April 2011
       Arctic Ice March 2011
       CBDunkerson : "If you actually measure out the years between 1500 and 2000 I think you'll find that the relevant values are (to the nearest 0.1 C); 1900: -0.2 1950: 0.0 2000: 1.0" It's a pity that we loose so much time on so simple things. ( -Baiting comment snipped- ) I read 1900: -0.4 1950: 0.2 2000: 0.3 so actually 85 % of the 1900-2000 increase occured before 1950, where apparently sea ice hardly varied. "Also: "And the biological proxies that are essentially summer responsive do show a much clearer increase at the beginning of century than now" Source?" uuuh ! Kaufman et al. 2009 !!! just said it. "It all depends on what the dominant factors driving recent ice decrease have been." ( -Baiting comment snipped- )
       Moderator Response: [DB] Kaufman et al 2009 does not say what you think it says nor mean what you say it means. I suggest reading it, not a news story based on it. And please refrain from baiting (no more warnings). To all: Please only reply to the portions of Gilles'comments with substance; we will deal with the rest.
89699. gallopingcamel at 23:15 PM on 7 April 2011
       Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
       Alley has something that is very useful in academia. He is very good at communicating with the general public. He is also approachable. If you send him an email there is a high probability that you will get a reply. I may not agree with him but I like his style.
89700. Bob Lacatena at 23:04 PM on 7 April 2011
       A Flanner in the Works for Snow and Ice
       

       Ken Lambert, "I cannot see how the high latitude areas of the Earth at incidence angles of +23 to -23 degrees could have the same area portion of heat gain as the tropics." Yes, Ken, we know that. We've tried repeatedly to explain it to you and you just can't (won't?) get it. No need to keep going back there.

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