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DSL at 03:50 AM on 8 April 2011Models 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. -
Marco at 03:43 AM on 8 April 2011Has 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). -
Gilles at 03:31 AM on 8 April 2011Arctic Ice March 2011
sorry for unclosed boldface tag -
Gilles at 03:30 AM on 8 April 2011Arctic 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. -
logicman at 03:24 AM on 8 April 2011Arctic 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. :) -
NewYorkJ at 03:20 AM on 8 April 2011Geologist Richard Alley’s ‘Operators Manual’ TV Documentary and Book… A Feast for Viewers and Readers
what Alexandre said... -
dana1981 at 03:15 AM on 8 April 2011Christy 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. -
arch stanton at 02:58 AM on 8 April 2011Geologist 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. -
Charlie A at 02:57 AM on 8 April 2011Has 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. -
KeenOn350 at 02:53 AM on 8 April 2011Christy Crock #1: 1970s Cooling
Nice post - very simple - you would think Christy could understand it! -
Ggf9191 at 02:47 AM on 8 April 2011Models 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. -
logicman at 02:42 AM on 8 April 2011Christy 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. :) -
trunkmonkey at 02:40 AM on 8 April 2011Climate'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. -
Albatross at 02:18 AM on 8 April 2011Christy Crock #1: 1970s Cooling
Beautifully done. Oddly, I was unaware of Rasool and Schneider (1971) until reading this. Very interesting. -
Nicholas Christie-Blick at 02:10 AM on 8 April 2011Skeptical 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. -
Albatross at 01:34 AM on 8 April 2011Geologist 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. -
Alexandre at 01:32 AM on 8 April 2011Arctic 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. -
Albatross at 01:29 AM on 8 April 2011Geologist 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? -
Alexandre at 01:21 AM on 8 April 2011Call 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 -
CBDunkerson at 01:17 AM on 8 April 2011Arctic 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. -
Bob Lacatena at 01:03 AM on 8 April 2011Arctic 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.
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bibasir at 00:58 AM on 8 April 2011Geologist 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. -
Albatross at 00:56 AM on 8 April 2011Arctic 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."
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CBDunkerson at 00:44 AM on 8 April 2011Arctic 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). -
Daniel Bailey at 00:34 AM on 8 April 2011Geologist 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 -
Alexandre at 00:02 AM on 8 April 2011Geologist 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. -
KR at 23:57 PM on 7 April 2011Upcoming 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. -
Arkadiusz Semczyszak at 23:37 PM on 7 April 2011Has 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. -
Gilles at 23:35 PM on 7 April 2011Arctic 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. -
DSL at 23:32 PM on 7 April 2011Human 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. -
Bob Lacatena at 23:23 PM on 7 April 2011Arctic 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
- 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.
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Gilles at 23:19 PM on 7 April 2011Arctic 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. -
gallopingcamel at 23:15 PM on 7 April 2011Geologist 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. -
Bob Lacatena at 23:04 PM on 7 April 2011A 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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CBDunkerson at 23:02 PM on 7 April 2011Arctic Ice March 2011
Gilles: "The graph from Kaufman et al. 2009 that I reproduced just above obviously contradicts this assertion." Let me guess, this is based on a 'highly scientific' eyeballing of the chart? 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 So no, that graph does not 'obviously contradict' my statement that the more recent warming has been much greater. Also: "And the biological proxies that are essentially summer responsive do show a much clearer increase at the beginning of century than now" Source? Finally: "Fine : so please can you predict the trend , say, in the 10 next years, and how ?" Actually, I'm of the school of thought that the Arctic ocean will be largely ice free at the annual minimum by then. A decent writeup on this position can be found here. The next three years or so should clear up alot of the remaining uncertainty about where Arctic sea ice is headed. Best case scenario, the volume will level off soon and we can then look forward to a longer slow decline down to largely ice free in September around 2035. On the other hand, if volume continues to drop at anything like the rate it has been then we'll be seeing ice free Septembers by around 2015. It all depends on what the dominant factors driving recent ice decrease have been. To my thinking the data since 2007 suggest that increasing influx of warm water and stronger currents have become the most significant factors, and thus we are likely to see continued declines. If, on the other hand, direct greenhouse warming of the Arctic region is still the dominant driver then we'd see a more gradual decline (though it then becomes difficult to explain the recent sharp drops). -
daniel maris at 22:53 PM on 7 April 2011Has sea level rise accelerated since 1880?
Muoncounter Well from your point of view, my approach is not a problem since I support a swift march to 100% renewable energy use starting now. I think we could do it within 20 years if we had the will. The latest from Israel where they are trialling battery changing statinos for cars suggests the range problem with electric vehicles has been resolved, so we can now look at a more or less complete and all-embracing solution. My reasons for favouring 100% renewables are many and various but do include a precautionary approach to altering carbon levels. But to adopt a precautionary approach is not the same as saying I buy into the reality of AGW yet. My view is that sea level rises would happen sufficiently slowly for humanity to react effectively. No relation to that Maris! -
les at 22:45 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
979 Tom - "What more could we ask for..." I wait, with trepidation, to find out! To me, it all seems so straightforward. Still, just because this discussion has certainly not gone on long enough - nor has it been repeated nearly sufficiently enough times on nearly enough blogs - can I suggest a further place for doubt? It turns out that in many multiverse models it is not clear that conservation of energy holds for the whole universe nor, indeed, for every universe. As such, I'm guessing I admit, it should be possible to have infinitely many universes in which the 2nd law doesn't hold, or possibly doesn't hold only for those gases which don't transmit/radiate/absorb evenly at all wavelengths or something. see, always room for doubt. -
Tom Curtis at 22:42 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
Fred Staples @976, I believe Les has adequately rebutted your comments about SOD.For any spontaneous transaction, anywhere in the known universe, the change in entropy must be positive.
This is incorrect. The Earth is infested with a spontaneous transaction which results in the formation of very low entropy products. It is called life. Of course, if you look at all energy flows involved in life, then the net entropy of the whole system increases, even though that in the living system decreases temporarily. So, only when we account for all energy flows within a boundary can we apply the 2nd law to the system within the boundary, and then it applies only to the entropy of the whole system, not to any arbitrary subpart of the system. As the worked example quoted above shows, when all energy flows are accounted for, the interchange of energy between Earth and atmosphere including back radiation involves a net gain in entropy, and hence no second law violation. And the second law applies only to the whole system, not to any arbitrary subpart - say, the backradiation alone."Now if a quantity of energy deltaQ leaves the atmosphere at a temperature Ta, ..."
Plainly your accounting considers only one energy flow within the system, not all of them. Therefore it is an attempt to apply the second law to an arbitrary subpart of the system rather than to the system as a whole, which is as explained above, a misapplication of the second law. -
MichaelM at 22:34 PM on 7 April 2011Arctic Ice March 2011
Prior to 1940 there seems not to be great deal of variance from: Winter 1 - 15 (Million sq k) Summer 1 - 11 Winter 2 - 15 (4 million k new ice) Summer 2 - 11 ... So 11 million k got to be multi-year ice i.e not "most of the ice in winter is just 6 months old anyway, every year". That we have less multi-year ice now is symptomatic of the problem. Or the above usage of 'most' could be just a language thing. -
Ken Lambert at 22:29 PM on 7 April 2011A Flanner in the Works for Snow and Ice
Tom Curtis #42 "Frankly, the implied dictum that you should only present some relevant information if you can present all relevant information is nonsense. What is more, it not one you adhere to, for if you had, you would not have made an argument based solely on the minimal relevant information of relative surface area of the arctic to the globe." Tom, wilfully leaving out relevant information of which you are aware simply is a distortion of the case to suit a particular bias. I did not rely 'Only on the surface area' of the Arctic to make my points. I quoted the calculations of the leading energy balance scientist in this field - Dr Trenberth. You say that Flanner has calculated that the heat sequestered in the Arctic is something like 9-10E20 Joules/year instead of 1E20 Joules/year from Trenberth's melting Arctic ice. The difference is supposed to be in the ocean. Well - where is your measurement of that? By the way if the imbalance portion is in fact 9-10E20 rather that 1E20 Joules/year then you were only wrong by 15 times rather that 149 times in your claim. I would like to see you out by only 100% rather that 1500% - however we can't have it all. If Dr Trenberth's 145E20 Joules/year net heat gain to the Earth was evenly distributed all over the surface then the Arctic's 4.4% would account for 6.4E20 Joules/year, which is still less than the 9-10E20 Joules/year claimed in Flanner. 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. -
Tom Curtis at 22:24 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
Les @977, an excellent read, and profitable for anyone following this debate. I particularly liked propater's comment:"If you take ScienceOfDoom example 3 and reverse it to consider radiation emmited by the atmosphere and absorbed by the earth’s surface, you can see that entropy is lost when the radiation from the atmosphere is absorbed by the hotter surface : Atmosphere: δS1 = -(390-301)/270 = -89 / 270 = -0.33 J/K Surface: δS2 = (390-301)/288 = 89 / 288 = 0.31 J/K This is right, net entropy equals -0.02J/K (as you say, “radiation quality” has increased since that energy will be re-emitted at a shorter wavelength) Entropy is reduced. This looks wrong. And it is! Because in that calculation you forgot one term: the radiation from TOA to space : If we suppose radiation from space to be j* = sigma * T^4 = 5.67*10^-8 * 3^4 = 4.59*10^-6 W/m² Let’s consider the entropy budget for one square meter for a second : Atmosphere: δS1 = -(390-0.00000459)/270 ~= -390/ 270 = -1.44 J/K Space: δS2 = (390-0.00000459)/3 ~= 390/ 3= 130 J/K Net entropy production from TOA-Space exchanges : 128.56 J/K Net entropy production from atmosphere exchange with the earth’s surface and space : 128.56 J/K – 0.02 J/K = 128.54 J/K. When you take all terms into account, no entropy is lost (even though some of it gets moved away.) In fact you see a massive amount of entropy created and, as Nick Stokes points out, it is the place where the entropy production is the largest (Sun-earth ~ 10 J/K.s.m², earth-atmosphere ~ 10^-2 J/Ksm² , atmosphere-outer space ~ 10² J/Ksm² )"
What more could we ask for - an actual worked example proving that back radiation does not violate the 2nd law of thermodynamics. Given this example, and the ease of the mathematics, I think it should be a minimum denier wanting to mount the tired old 2nd law argument that they provide such a worked example of their model of the greenhouse effect. It should make the arguments much shorter and to the point, and provided an easy way to keep score of who is correct, and who is simply full of it. -
Ken Lambert at 22:10 PM on 7 April 2011Skeptical Science in other media
I did not think that being forgiven by supernatural beings had anything to do with the science (or sub-science) of AGW. I must admit that if there were a logic to an object of worship - worshipping the Sun made primitive and scientific sense. After all, from the Sun is where all this troublesome warmth cometh. -
Gilles at 21:59 PM on 7 April 2011Arctic Ice March 2011
Michael : "winter ice used to be 15 million sq k and dropped to 11 in the summer i.e 4 million was new ice." ??? 6 months after being 15 or 10 millions km^2, winter ice becomes summer ice , with an extent between 4 and 5 Mkm^2 - so most of the 10 to 15 Mkm^2 of each year are only 6 months old anyway. -
Gilles at 21:55 PM on 7 April 2011Arctic Ice March 2011
162 : les: I'm flattered that you waited until I didn't recognize a famous sentence before concluding english is not my mother language (I'm French - it's "Gilles" and not "Giles").But CB 164 : "However, they can and have been used to predict the trend of the decline." Fine : so please can you predict the trend , say, in the 10 next years, and how ? "Arctic temperatures have risen much more in the recent warming phase than they did in the earlier part of the century." The graph from Kaufman et al. 2009 that I reproduced just above obviously contradicts this assertion. And the biological proxies that are essentially summer responsive do show a much clearer increase at the beginning of century than now - so how do you explain that tree and lake sediments appeared to feel much more variable warmth in summer, at the beginning of the XXth century than sea ice ? another try ? -
Tom Curtis at 21:53 PM on 7 April 2011Muller Misinformation #1: confusing Mike's trick with hide the decline
Ryan Starr @123, it is a common conceit of deniers that any absurdity they do not adhere to is not promulgated by any denier. By ignoring the claptrap sprouted by their fellow deniers, they not only avoid disagreeing with those deniers, and recieving the blast of invective that normally accompanies such disagreement; but they also get to pretend that the supporters of AGW theory are arguing against a strawman. The pretence is disengenuious, and in fact many deniers do in fact claim that "hide the decline" refers to a fraudulent concealment of a decline in mean global surface temperatures as measured in the instrumental record. As to Starr's claim that Jones and Manne are "hiding the evidence", publishing the evidence, drawing attention to the discreprancy, and then discussing it in several papers, then citing those discussion in all other papers where the data is used is a funny way to hide something. In fact, in most circles that is considered drawing attention to the problem. But not, apparently, in denier circles, when the publishing, discussing, and citing is done by a climate scientists. -
Dikran Marsupial at 21:35 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
Fred@975 It seems to me that the source of the disagreement here is that you view backradiation as a separate theory, rather than as a component part of the "top of the atmosphere" explanation. AFAICS this is incorrect, it is backradiation that causes the surface to warm until equilibrium is re-established following an increase in the height of the emitting layer at the top of the atmosphere. -
les at 21:31 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
976 Staples SoD seems quite comfortable with Entropy. -
CBDunkerson at 21:22 PM on 7 April 2011A Plan for 100% Energy from Wind, Water, and Solar by 2050
Vladimer: "The problem is that almost all of that is hypothetical." If you had actually read the article you might have noticed the part about; "we consider only options that have been demonstrated in at least pilot projects and that can be scaled up as part of a global energy system without further major technology development." Renewable energy technology does not require further development to replace most fossil fuel use. The current state of development is more than sufficient and getting better rapidly. -
Fred Staples at 21:16 PM on 7 April 20112nd law of thermodynamics contradicts greenhouse theory
As I posted my last contribution, I noticed that we are to be favoured by another post from SOD. I debated back radiation theories with someone I believed to be SOD in Eli Rabett’s blog, some time ago. Quoting from memory, SOD based his argument on the conservation of Energy (“where does the energy go”?) He freely admitted that, for him, entropy “never seemed real” and its formula deltaS = DeltaQ/delta T did not make sense (which, since that version is wildly wrong, is not surprising). No-one should comment on AGW (or anything else, in my opinion) without a reasonable grasp of the second law of thermodynamics. For any spontaneous transaction, anywhere in the known universe, the change in entropy must be positive. Now if a quantity of energy deltaQ leaves the atmosphere at a temperature Ta, the change in entropy is -deltaQ/Ta.If it is absorbed by the surface, at a temperature Ts, the change in entropy is +deltaQ/Ts. Now, since Ta is less than Ts (the lapse rate again), the combined change in entropy is negative, which is forbidden. If it happens on the microscopic level (vibrating molecules in a steel bar, heated at one end, or photons from a cold plate to a hot plate), it must be accompanied by a greater transfer in the conventional direction, hot to cold. It cannot be considered or analysed in isolation, which would take us immediately to a search for perpetual motion, as G and T point out at excessive length. By transferring from a hot source to a cold sink, energy becomes heat which can produce work. No net change is possible in the opposite direction without a heat engine. So to answer the question posed in the introduction, have climate scientists made an elementary mistake in explaining AGW? Of course not. Have most of the bloggers, politicians and journalists? Undoubtedly. -
CBDunkerson at 21:13 PM on 7 April 2011Arctic Ice March 2011
Gilles: "is there any clear parameter in the past (such as the value of last minimal, or maximal extent, the amount of < X years old ice, etc..) that would be useful to predict the next minimum, and allow such predictions to be made with a significative success ?" No. None of the factors causing the ongoing trend of Arctic ice decline is consistently greater than short term weather variations. Ergo, no single such factor, nor even a combination of factors, can be used to precisely predict results in individual years. However, they can and have been used to predict the trend of the decline. Also: "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 ?" Global != Arctic Arctic temperatures have risen much more in the recent warming phase than they did in the earlier part of the century. Further, as others have noted, the existing ice was much thicker in the past and thus the ice-albedo feedback effect was nowhere near as pronounced as it is now. That said, my recollection is that the perfect flat line in a few spots on that graph is due to lack of data for those years. Still, a gradual decline in Summer ice extent (i.e. the period most impacted by warming) can be seen in conjunction with the earlier warming period and a more pronounced decline with the current more pronounced Arctic warming. Finally: "so why the temperature change in the 1900-1950 period has not produced any change in the sea ice extent" As I noted, the Summer data does show a decline in the 1900-1950 period. Ignoring that in favor of the periods where warming would have less impact is essentially a return to the 'conditions have been reset' argument that you claimed you are not making.
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