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Comments 78651 to 78700:

78651. barry1487 at 12:52 PM on 25 July 2011
       Milankovitch Cycles
       Yes, I thought the equivalent warming of both hemispheres over Milankovitch cycles was strong evidence, firmly corroborated by the ice core (and other) records of both hemispheres, that GHGs play a significant role in global temperature changes. The only other mechanisms I can think of for this effect are atmospheric teleconnections and lateral heat transport via ocean currents, but even so, hemispheric temperatures would be significantly different for periods where one hemisphere is receiving more insolation than another - except for GHGs.
78652. Paul Magnus at 12:51 PM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       #20 Bad, Yes, but peer review information is now coming out indicating that, especially if we dont reduce our rate of emission, but even if we do, that we might (could) get 5-6ft by around 2100. And then it will keep going up and up.... They take about 6ºC giving 4ms, but we can see in this article (& from Hansen) that a 1ºC rise from now will result in a 8m rise at some point. What this article shows also is that it is not stopping there, but will continue on to around 20ft+ even if we do stop our emissions as there is at least .7ºC in the pipeline and probably more. We also have to get back to around 350ppm and below before we see equilibrium (Hansen). It really does not make sense for the Netherlands to spend billions and billons to defend when they will have to retreat. That money could be better spent. This reality has to enter the debate now. Nothing is certain, but this is looking more and more certain with each year! And the current data should cause pause for re-review of strategy I would guess considering the cost.
78653. villabolo at 12:33 PM on 25 July 2011
       SkS Weekly Digest #8
       
78654. Riduna at 12:19 PM on 25 July 2011
       China, From the Inside Out
       Tom Curtis @84 I would have thought it obvious from my remarks made it clear that the last thing I expect is for any country to be excused reducing their emissions. Your suggestion that I expect poorer nations to bear the burden of reducing their emissions is as fallacious as suggesting that a 50% increase in China’s emissions is conducive to limiting global warming to less than 2C.
78655. Doug Mackie at 11:19 AM on 25 July 2011
       OA not OK part 10: Is the ocean blowing bubbles?
       Fixed.
78656. Bern at 10:51 AM on 25 July 2011
       OA not OK part 10: Is the ocean blowing bubbles?
       "However, this amount of released fossil fuel CO2 is less than the amount of extra CO2 that is currently in the atmosphere." Should that be greater than?
78657. Bern at 10:41 AM on 25 July 2011
       OA not OK part 9: Henry the 8th I was (*)
       Doug, no, my opinions on climate change are almost diametrically opposed to Ken's. :-)
78658. pauls at 10:34 AM on 25 July 2011
       Monckton Myth #16: Bizarro World Sea Level
       There appears to be no end to the hilarity that can be drawn from Morner's recent work. This quote from his 2004 paper Estimating future sea level changes from past records is brilliant: 'IPCC launched their hypothesis of a disastrous flooding of coastal low-lands and low islands (like the Maldives) in the next century (e.g. Hoffman et al., 1983).' That's right, his example of the IPCC (founded in 1988) hypothesis of disastrous flooding is a paper from 1983. The 'modelled vs observed' graph is actually appears to be a comparison between Church & White 2006 and a multi-source record described in Morner 2004. The Church & White data can reasonably be termed 'model data' since they use a model to infer global sea level change from coastal tide gauge data back to 1870. However, in no way could this be termed a 'prediction', as suggested in the legend. How Morner arrives at the 'observations' plot is interesting. The data from 1840 to 1960 is quite reasonably a mean of tide gauges, giving a fairly standard average SLR of ~1.2mm/yr over the whole period. Then things get weird. He states 'During the 1970s and 1980s, our data are not really clear enough for a proper evaluation of any general trend in sea level.' How this could be isn't explained but, undeterred, he moves right on to the satellite era (~1990 to present) which he determines shows no trend, contradicting everyone else in the world with no explanation. Note on the graph that there is also no trend from about 1960 to 1990. How was this determined given the documented sudden loss of data during the 70s and 80s? Well, his only reference that includes this period is to calculated contributions to sea level change over 1910-1990 from various sources, as documented in IPCC TAR 2001. He cites the figure 0.9mm/yr though it's unclear from where because the central value given by the IPCC is actually 0.7mm/yr (Link). So the curve after 1960 is an attempt at reconciling the long-term 1.2mm/yr trend with the IPCC 0.9mm/yr (0.7mm/yr) figure to 1990. And I think he massively overdoes the 'correction' too. No matter though, the great thing about this is that the IPCC figure is largely derived from modelling studies. So the point at which the 'models' and 'observations' diverge is the point at which the 'observations' become 'models'.
78659. Dcrickett at 10:34 AM on 25 July 2011
       OA not OK part 10: Is the ocean blowing bubbles?
       Mr Smith: Excellent question; thanks for asking it. I too am curious.
78660. Tom Curtis at 10:30 AM on 25 July 2011
       China, From the Inside Out
       Agnostic @83, your argument is most commonly coupled with the argument that because China is not reducing its emissions, then Australia and the US ought not to reduce their emissions because doing so would merely cripple their economy without effecting our long term prospects of combating global warming. At the very minimum the chart @82 shows this is false. In fact, that argument pair is always just a rhetorical device to block effective action on climate change with out directly arguing against action on climate change. It is difficult to see how your position differs. Specifically, there is no hope in the world that China, or India will sign up to emissions reductions at a rate comparable to those of the west in terms of absolute emissions per nation. Nor should they. There will undoubtedly be a short term cost in moving to a zero (or very low) emission economy. The demand for equal per nation reduction in emissions is therefore a demand that the poorest nations accept a greater cost so that the wealthy nations that have caused the problem can minimize their costs in the transition. Quite apart from any consideration of equity, the fact is the cost for western nations will be easily paid out of discretionary income from the household budget. In Third World nations the cost will be in terms of the elimination of health services, and of educational opportunities, and in many cases the ready availability of food. For China the cost of an equal per nation reduction will be eliminating the growth of the middle class. Economists have a useful term for analyzing costs. It is "utility". In rough terms, the utility cost is the cost in actual happiness or opportunity. In those terms, because fighting global warming means, for the West, trimming luxuries, and for the third world, trimming necessities, the utility cost in the third world is far higher for an equal reduction in emissions. Therefore your policy prescription is that the third world bear a greater cost in necessities so that we can have a reduced cost in luxuries for any given outcome. The proper response to that to anyone, including you, is that if you think the situation so lacking in urgency that you are prepared to haggle amount how many luxuries you will give up, then it is insufficiently grave for the third world to give up a single necessity.
78661. John Hartz at 10:17 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       @ Paul Magnus #11: Exploring high-end climate change scenarios for flood protection of the Netherlands Ministerie van Verkeer en Waterstaat (VenW) P. Vellinga, C. Katsman, A. Sterl, J. Beersma, W. Hazeleger ...(etc.), Koninklijk Nederlands Meteorologisch Instituut, 2009 This international scientific assessment has been carried out at the request of the Dutch Delta Committee. The Committee requested that the assessment explore the high-end climate change scenarios for flood protection of the Netherlands. It is a state-of–the art scientific assessment of the upper bound values and longer term projections (for sea level rise up to 2200) of climate induced sea level rise, changing storm surge conditions and peak discharge of river Rhine. It comprises a review of recent studies, model projections and expert opinions of more than 20 leading climate scientists from different countries around the North Sea, Australia and the USA. Although building on the previous IPCC AR4 (2007) and KNMI (2006) assessments, this report deliberately explores low probability/high impact scenarios, which will pose significant threats to the safety of people and infrastructure and capital invested below sea level. According to its high-end estimates global mean sea level may rise in the range of 0.55 - 1.10 m in 2100 and 1.5 - 3.5 m in 2200, when higher temperature rise scenarios (up to 6 °C by 2100) and increased ice discharge from Antarctica are considered. This would correspond with local sea levels along the coast of the Netherlands of up to maximally 1.20 m in 2100 and 4 m in 2200. An increase in peak discharge of river Rhine of 3 to 19% for 2050 and 6 to 38% for 2100 is foreseen. The storm regime along the Dutch North Sea coast in terms of maximum surge level will probably not change significantly in this extreme climate change frame. To access the PDF of the full report, click here.
78662. muoncounter at 10:07 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Paul Magnus#11: "as these data come out surely they will have to reconsider and start thinking about retreat" Check it for yourself at this sea level rise mapping site. Even at +2 meters, its not pretty for Rotterdam, Amsterdam, Gronigen, etc.
78663. Riduna at 09:38 AM on 25 July 2011
       China, From the Inside Out
       Tom Curtis @ 78 The points I make is that only nation-states can (and should) exercise control over their CO2-e emissions. Those emissions are and should be measured in national total tonnage and it ought to be recognised as the basis for international agreements. Global warming occurs because of total CO2-e emissions, the aggregate of total national emissions, irrespective of variance in per-capita emissions among nations. I do not subscribe to the view that, by virtue of having a large population, it is acceptable for China to increase its emissions by ~50%, from its present 7.7 gigatonnes per annum to >11 gigatonnes per annum, or that this is consistent with limiting temperature increase to <2°C by 2100. And there is certainly no evidence that China has either the intention or capacity of reducing its emissions to zero by 2030. Such proposals are unrealistic and dangerous for our future. It is wrong to equate the right to higher per-capita energy entitlement with the right to increase CO2-e emissions. No one disputes that China or India have a right to improve the standard of living of their vast populations by increasing availability of per-capita energy. What is disputed is that this justifies increasing CO2-e pollution or that such an increase is unavoidable and necessary. Global CO2 emissions are approaching 400ppm compared with a “safe” target of 350ppm. The world is heading for a catastrophic 4-5°C increase by 2100, sea level rise of at least 1m, possibly up to 5m and a climate so extreme that our ability to survive will be sorely challenged – yet it is seriously suggested by commentators that major increase in CO2 pollution is justified. My response is and remains NO!
78664. Robert Murphy at 09:33 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Climate4All@15, A one paragraph prediction in Popular Science (repeated in Popular Mechanics) by someone who was mostly an anthropologist is supposed to be well known to people discussing climate science? Where is there any indication this prediction was ever reported beyond this cite? And your quote is incomplete. Here is the full one (which your link actually provided in full): "Sea level the whole world over is five inches higher than it was in 1895, says Dr. George F Carter, Johns Hopkins University geographer. Because this is the tail end of a glacial period, polar ice is melting and filling up the oceans. Future harbor works should be planned for an expected sea level rise of 24 inches within the next century, Dr. Carter advises" And it should be noted he's just wrong; sea level was not rising because "this is the tail end of a glacial period". We have been in the middle of an interglacial for thousands of years. If he meant the "Little Ice Age", he would still have to provide a physical reason for why sea level started rising; it didn't start rising because it had been colder before. Sea level had been rising because of a combination of increased solar irradiance and rising GHG's warmed the Earth. Since the middle of the 20th century, the warming has been primarily from GHG's. The musings of someone without a lot of background in sea level rise speaking at a time when that science was in its infancy, and quoted in 2 magazines for laymen has no relevance to the science as it is now. Why bring him up? His prediction had no influence.
78665. Rob Painting at 09:24 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Pirate @ 12 - the 'eyecrometer' is not a precise tool, hence the use of statistical analysis: Sea level rise is accelerating. See Church & White (2011) and this SkS thread From the study: "There is considerable variability in the rate of rise during the twentieth century but there has been a statistically significant acceleration since 1880 and 1900 of 0.009 ± 0.003 mm year and 0.009 ± 0.004 mm year-2 , respectively. Since the start of the altimeter record in 1993, global average sea level rose at a rate near the upper end of the sea level projections of the Intergovernmental Panel on Climate Change’s Third and Fourth Assessment Reports" And to illustrate the point about IPCC sea level projections and actual observations (your last graphic isn't clear enough): Actual sea level rise is tracking the upper bound of projections. Pirate - "So, whether we look at 18 years, 120 years, or 8,000 years we are seeing a linear response." Let's check the last 2000 years or so. Discussed in: A sea level hockey stick No linear sea level response there either.
78666. John Hartz at 09:09 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Let us also not loose sight of the fact that sea level rise is not distrubuted uniformly throughout the Erath's ocean systems. To learn more about this topic, go to: SkS Thinning on top and bulging at the waist: symptoms of an ailing planet
78667. scaddenp at 09:01 AM on 25 July 2011
       Human CO2 is a tiny % of CO2 emissions
       Ken, please see the thread Water vapour is the most important greenhouse gas.
78668. scaddenp at 08:53 AM on 25 July 2011
       Sea level rise is exaggerated
       Eric the Red, you may be interested in the analysis of this paper How not to analyze tide gauge data. While this analysis isnt published (though I am encouraging the author to do so) it is basically the same cherry pick as H&D. See here for published criticism of this kind of cherry pick.
78669. Climate4All at 08:46 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       @Composer99 A citation wouldn't be necessary if those that said they were knowledgeable of facts, were actually knowledgeable of the facts. Dr. George F. Carter was quoted as saying, “Sea level the whole world over is five inches higher. Because this is the tail end of a glacial period, polar ice is melting and filling up the oceans. Future harbor works should be planned for an expected sea level rise of 24 inches within the next century.” This quote and another like can be found in Popular Mechanics Mar'53 and Popular Science Feb.'53. George F. Carter taught at John Hopkins University as acting chair of the Geography Dept., and at Texas A&M as Distinguished Professor of Geography. Before he taught at John Hopkins, he served as an analyst for the Office of Strategic Services(better known as the C.I.A.), during WWII. Two papers worth reviewing his extensive work are: EARLY MAN AT SAN DIEGO: A GEOMORPHIC·ARCHAEOLOGICAL VIEW & MAN, TIME, & CHANGE IN THE FAR SOUTHWEST. Or, if you like, there are many reviews of his works on geography/anthropology. If he was alive today, he would probably tell you that he was a climatologist as well. In his work, he used sediment readings from many parts of the world and had concluded that there have been at least 2 interglacial periods before this current one and that seas had risen 100s of feet before, and quite likely, will do so again. Dr. Carter had even mentioned that without some sort of relapse(cooling), that the seas could repeat the process again, possibly in our lifetime or our children's lifetime. Dr. Carter passed away in 2004. He will be missed.
       Response:

       [DB] "A citation wouldn't be necessary if those that said they were knowledgeable of facts, were actually knowledgeable of the facts."

       A citation was politely asked for.  Perhaps emulating civil behavior by responding politely sans attitude would allow for better engagement and dialogue.

       Or you can continue down this path and we can see what happens.

       Your call.

78670. Byron Smith at 08:44 AM on 25 July 2011
       OA not OK part 10: Is the ocean blowing bubbles?
       Thanks - excellent summary of an important point that is much misunderstood, but has to be one of the most secure pieces of the big climate puzzle (not saying that other pieces do not have good evidence, but this one is, in my impression, totally in the bag and can be a good test of whether people are really out to lunch if they continuing questioning it). This post actually gave me a small piece of reassurance in saying that for the oceans to become a major net carbon source, they would have to warm a loooong way (especially since oceans warm much slower than atmosphere). One of the concerns about warming oceans is that their function as a carbon sink will decline, leaving more of our CO2 in the atmosphere. This is one of many potential positive feedbacks that magnify a small change into a bigger change. But even if the ocean declines as a carbon sink (which is bad), it seems unlikely to become a carbon source anytime soon (which would be really, really bad). And so here is my quick question on this topic: how much would the oceans have to warm to make the switch from sink to source?
78671. scaddenp at 08:43 AM on 25 July 2011
       Milankovitch Cycles
       Camburn, did you read #17? The change in albedo (largely) in NH sets up GHG feedbacks which are global not hemispheric. No puzzle at all.
78672. muoncounter at 08:36 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       pirate#12: "So, whether we look at 18 years, 120 years, or 8,000 years we are seeing a linear response." See the prior thread, Has sea level rise accelerated since 1880? Whether sea level showed 20th-century acceleration or not, it’s the century coming up which is of concern. And during this century, we expect acceleration of sea level rise because of physics. Not only will there likely be nonlinear response to thermal expansion of the oceans, when the ice sheets become major contributors to sea level rise, they will dominate the equation. Their impact could be tremendous, it could be sudden, and it could be horrible.
78673. Tom Curtis at 08:28 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       eldorado2768, a time and date stamp for each frame is in the top left corner. The data also shows the location (latitude and longitude and pitch), but not the internal temperature which I know to be recorded :(. Anyway, the time interval is from early March 22nd to July 22nd, 2011.
78674. Tom Curtis at 08:23 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       apirate @12, the IPCC projections are not linear, and explicitly exclude melt water from glaciers because they are not sufficiently predictable. Those glaciers will melt, however, or at least a significant amount of the Greenland Ice Sheet and the West Antarctic Ice Sheet will melt although it will probably take centuries to do so. Based on your second graph (from wikipedia, I believe) the sea level rose 115 meters in the 8 thousand years from 16k before present to 8 k before present. That represents a rate of rise of 144 mm/decade, and is a reasonable projection for the rate of rise by the end of this century. That would yield a sea level rise in the order of 650 mm by 2100, and double that for the following centuries until the 6 to 8.5 meter rise above current levels is achieved, assuming we restrict GHG emissions sufficiently to restrict global temperature increases to 2 degrees C. Contrary to many commentators here, I believe that those rates are well withing the economic means for adaption; but I also think sea level rise will cause the least economic hardship globally of the various risks from global warming.
78675. muoncounter at 08:20 AM on 25 July 2011
       The Medieval Warm(ish) Period In Pictures
       Camburn#56: "I have not seen any rebuttals to the Sargasso Sea temperature proxies." Perhaps not. However, here is an excellent rebuttal to the numerous misrepresentations of Keigwin's Sargasso Sea data that continue to rebound throughout deniersville. Keigwin’s Fig. 4B (K4B) shows a 50-year-averaged time series along with four decades of SST measurements from Station S near Bermuda, demonstrating that the Sargasso Sea is now at its warmest in more than 400 years, and well above the most recent box-core temperature. Taken together, Station S and paleo-temperatures suggest there was an acceleration of warming in the 20th century, though this was not an explicit conclusion of the paper. Keigwin concluded that anthropogenic warming may be superposed on a natural warming trend. ... Keigwin’s Fig. 2 showed that δ18O has increased over the past 6000 years, so SSTs calculated from those data would have a long term decrease. Thus, it is inappropriate to compare present-day SST to a long term mean unless the trend is removed. -- emphasis added This analysis, Misrepresentation of Scientific Data by Hillary Olson at UT, is based on a 2010 GSA talk by Boslough and Keigwin. It features a point-by-point demonstration of the manner in which deniers cherry-pick from a legitimate study, modify, distort and misrepresent. It includes a discussion of how internet memes arise and gain traction despite being factually incomplete or incorrect. This particular 'Saragasso Sea was warmer way back when' meme is traced to the folks behind the Oregon Petition. For the benefit of any skeptical educators, Olson includes the relevant sections from the Texas Essential Knowledge and Skills (TEKS): The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: (A) in all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student; (B) communicate and apply scientific information extracted from various sources such as current events, news reports, published journal articles, and marketing materials; (D) evaluate the impact of research on scientific thought, society, and public policy; It is too bad those skills are in such short supply these days.
78676. eldorado2768 at 08:12 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       What timeframe do the spliced images cover? I think that would be helpful information.
78677. Tom Curtis at 08:04 AM on 25 July 2011
       China, From the Inside Out
       Byron Smith @80, the original for the graph comes from the WBGU report, "Solving the Climate Dilemma: The Budget Approach" (PDF). It is an excellent policy advisory document, and maintains neutrality between various policy options, including an historical responsibility approach, in which each nation has a per capita budget starting in 1990 (which has been already spent in the case of the US and Australia). I tend to ignore it as I do not think it would ever be accepted by the US. I do apologize for the condition of the original graph. I was posting away from home, and did not have access to my favourites bar. Here is a better version from SkS:
78678. Robert Murphy at 07:49 AM on 25 July 2011
       Human CO2 is a tiny % of CO2 emissions
       Ken at 123: "Why doesn't the GHG chart include Water Vapor..." Because it is an emissions chart. Our emissions have no direct effect on global water vapor levels; those levels are a direct function of global temps, and essentially nothing else. Water vapor is the only GHG that will precipitate out of the atmosphere at temps we experience. The other GHG's stay aloft a lot longer, in particular CO2. Water vapor really only acts as a feedback, not as a forcing. Our emissions of other GHG's are forcings.
78679. michael sweet at 07:48 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       The melting of the ice shelves on Ellesmere Island show that the Arctic ice is at the lowest level in at least the last 5,000 years. Since 2011 is currently lower than any other year measured, that means 2011 is the lowest for July 24 in at least 5,000 years. A Pirate: can you suggest a 5,000 year cycle that is peaking that would account for this collapse of the ice? If no such cycle can be proposed that indicates that the extraordinary melt this year is not due to natural cycles but instead to human influence. Please provide references to data to support your "natural cycles". It is not enough to suggest "natural cycles". You also have to provide data to suggest they exist. Without data you are just waving your hands.
78680. apiratelooksat50 at 07:39 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Muoncounter @ 3 If we go back 130 years we see the basically the same trendline. Going back 24K years we see a sharp rise following the meltwater pulse following the last glacial maximum. That sharp rise leveled out about 8K years ago to what we are experiencing now. And, from IPCC 3 we get their sea level projections. So, whether we look at 18 years, 120 years, or 8,000 years we are seeing a linear response.
78681. Ken at 07:34 AM on 25 July 2011
       Human CO2 is a tiny % of CO2 emissions
       Why doesn't the GHG chart include Water Vapor, which is, I believe, the largest GHG? When Water Vapor is included as a GHG, it represents 95% of the GHGs. I thought it was well established that Water Vapor plays the largest role in keeping the Earth at a temperature that will support life. We do not seem to be considering all the variables here.
       Moderator Response: See "Water vapor is the most powerful greenhouse gas."
78682. HK at 07:26 AM on 25 July 2011
       Milankovitch Cycles
       Camburn, if you compare the CO2 levels at Mauna Loa and the South Pole, you will see that they follow each other quite closely, despite the fact that the levels are rising much faster now than at the end of the last ice age. When the SH responds to the change in GHG’s, this response will cause a positive albedo feedback just as in the north, although not as strong. And BTW, one of the Milankovitch cycles, the obliquity or axial tilt, will affect both hemispheres in the same way as both poles get more insolation and the tropics get less.
78683. Paul Magnus at 07:25 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       I bet no body really believes this, otherwise we would all be clamoring to address it! I wonder how Holland is reacting to these latest findings on the sensitivity of the ice to temp rise? They have opted for defense, but as these data come out surely they will have to reconsider and start thinking about retreat as the main strategy. Where are they all going to go?
78684. Composer99 at 07:25 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Climate4All: {citation needed}
78685. Paul Magnus at 07:20 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       "We expect something quite different for the future because we're not changing things seasonally, we're warming the globe in all seasons," McKay said." Surely the main forcing once warming got underway was GHGs which reenforced the seasonal warming and at some point takes over. Would be interesting to find this point where the ghg feedback takes over from orbital forcing....
78686. Byron Smith at 07:15 AM on 25 July 2011
       China, From the Inside Out
       Ah, found it (scroll down). It was used by Potsdam Institute Director Professor Hans Joachim Schellnhuber in his presentation to the "4 Degrees & Beyond" conference in Oxford, 2009.
78687. Paul Magnus at 07:11 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       "McKay pointed out that even if ocean levels rose to similar heights as during the Last Interglacial, they would do so at a rate of up to three feet per century." err ... how does he come by this. I think he means average rate. The rate is by no means going to be steady. There are documented cases of large SLR over short time scales. Our CO2 forcing is ballistic compared to interglacial ones so I would think we will see spectacular ice collapse maybe sooner than later... "Even though the oceans are absorbing a good deal of the total global warming, the atmosphere is warming faster than the oceans," McKay added. "Moreover, ocean warming is lagging behind the warming of the atmosphere. The melting of large polar ice sheets lags even farther behind." I have seen graphs on this site indicating that most of the warming went in to the ocean. So am a bit confused by this statement.....
78688. Byron Smith at 07:08 AM on 25 July 2011
       China, From the Inside Out
       BTW, Tom, I know I've seen that figure before, but since I can't remember where it was, can you please link to the source? (The graph currently links to the very informative and important Climate Commission Report "The Critical Decade" which is well worth reading in its own right, but doesn't contain that figure).
78689. Bob Lacatena at 07:01 AM on 25 July 2011
       Milankovitch Cycles
       25, Camburn, As Dan and Dikran have pointed out... I don't see how your comment makes any sense. The two halves of the planet are quite obviously not separated by a giant, plexiglass divider. If a massive change in albedo in the northern hemisphere due to expanding or retreating year-round snow/ice cover reflects or absorbs a notably different amount of incoming solar radiation, then that is energy the planet loses/gains, period, year after year, for millenia. Once that starts, the feedbacks start. That the change is initiated in one hemisphere only seems entirely inconsequential. The global temperature will rise/fall as a result.
78690. Dikran Marsupial at 06:44 AM on 25 July 2011
       Milankovitch Cycles
       Camburn IIRC the glaciations are caused by Mlankovic forcing, but the temperature changes are amplified by CO2 feedback. This feedback will apply to both hemispheres as CO2 does diffuse between hemispheres with a lag time of a year or two. Thus as far as I can see, glaciation in both hemispheres is not unduly surprising.
78691. Camburn at 06:17 AM on 25 July 2011
       Milankovitch Cycles
       HK@24: The problem with this is that glaciation is mutual to both hemispheres. That fact shows the albedo etc links do not function. This is one of the puzzling things about the cycle amongst many others.
       Response:

       [DB] The fallacy you fall into is the expectation that hemispherical glaciation is symmetrical, which it is not.  Consider the hemispherical distribution of land vs water to gain a sense of the size of the mismatch (and the subsequent relative changes in albedo between glaciation and interglacial). 

       So your "fact" is completely NOT one.

78692. Albatross at 05:38 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       Daniel @10, This is not "ordinary" melt. Look at the northernmost extent of the September ice minimum. Now compare that with the loss of ice at the location of the web cam. The ice margin is now (in late July) much further north than it is during the northernmost extent of the ice margin typically observed at the September minimum. Tom already made this point back @6, but apparently it needs repeating. The title is not misleading at all.
78693. Climate4All at 05:28 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Back in the early 50's, a group of scientists had predicted that sea levels would rise higher than the predictions made by the IPCC 50 years later. Their analysis then was because we are at the end of interglacial period. I don't remember there being any type of hysteria then as opposed to now. Only now though, it's frightening and catastrophic because its man-made. What interesting times we live in.
78694. Byron Smith at 05:22 AM on 25 July 2011
       China, From the Inside Out
       @Tom Curtis (#78) - Excellent answer, thank you. And that final graph is very important (though unfortunately, the x-axis has been cut off?), even though it is based on the assumption of no reparations for any previous carbon "debt" incurred by the nations that have benefitted most from a long history of emissions, but simply assumes that per capital emissions ought to be equalised from here as quickly as possible while overall emissions drop fast enough to give us a 75% chance of staying below 2ºC rise from pre-industrial temperatures by 2100. (Remember, 2ºC is still a *big* and nasty change, and should not be considered "safe", just not nearly as bad as 3ºC would be. 4ºC? Don't even think about it... (though that's where we're currently headed if all nations follow through on their commitments thus far)). So, to summarise: Australia/US/Canada (Canada fits basically in line with US and Oz for per capita emissions) have the most pressing reasons for reducing carbon emissions as soon as possible and basically as far as possible.
78695. HK at 05:11 AM on 25 July 2011
       Milankovitch Cycles
       Hi! I have followed skepticalscience for a while without participating in the discussions, and my only contribution so far is the Norwegian translation of The Big Picture. Regarding how the Milankovitch cycles impact the solar insolation globally, I found an interesting graph on page 18 in the paper Target CO2 by James Hansen & Co. As you see, the difference between maximum and minimum global insolation during the last 400,000 years is only about 0.5 Watts/m2 with present day geographical and seasonal distribution of albedo. Assuming a slow-feedback climate sensitivity of 1.5 C / W/m2 gives a total climate change of only 0.75 C, much less than the 5 C difference between LGM and the Holocene. If the albedo was evenly distributed globally and not higher in the northern hemispere, the Milankovitch cycles wouldn’t be able to change the global average insolation at all. The reason why northern hemisphere is controlling the glacial cycles seems obvious to me: It’s not just because Arctic sea ice responds much faster than the Antarctic ice sheet, but because NH hemisphere has much larger areas that undergo positive albedo feedbacks during warming or cooling. Just compare the huge changes in NH ice sheets between LGM (south to about 40 N in North America and 50 N in Eurasia) and today (Greenland) and the much smaller changes in the geographically isolated Antarctica. Then we have the changes in the boreal forests known as the "taiga". During the ice ages the taiga wasn’t just pushed southward and replaced by ice sheets and tundra. The ice age climate was generally dryer than today, so much of the taiga (and also temperate forests) was replaced by open grassland (steppe, prairie etc) which has considerably higher albedo than the dark green coniferous forests that make up most of the taiga. The SH of course has nothing similar to this. And finally we have the snow cover in temperate latitudes in winter. That snow cover would also expand southward and increase the NH albedo even more. Some may argue that this albedo increase wouldn’t matter much because it happens in winter when insolation is low, but at 40 N in late winter the solar elevation angle at noon is about the same as in northern Norway in June. The areas in SH with a cold temperate climate (snow in winter) is negligible compared to NH and would expand far less during an ice age than in the NH. So, the albedo feedback is much stronger in the north than in the south because of the distribution of the continents, and as Sfaerica mentioned above, this will have an effect on levels of CO2 and other GHG’s which will spread the warming (or cooling) to the southern hemispere.
78696. Daniel J. Andrews at 04:46 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       I must admit I found the title a bit misleading too although it is technically accurate, and I'm certainly not in the denier category either--I do guest lectures on climate change at the local university for students and tie it in to my field (ecology and biology). Instead, I thought this post might be showing something similar to that fantastic time-lapse video I saw on TED where enormous ice-sheets are melting back over a three-year period, even during the winter. Or new time-lapse video from space showing melting over a decade or more. Those were gripping! Scary too. I didn't expect to see seasonal melting, which in my perhaps northern Canadian-inured opinion, doesn't merit a "gripping", so for me, and maybe me alone, I found the title misleading. Not that you need to change it--if the deniers want, they'll take anything you write, say, do and twist it to suit their narrative anyway (e.g. the whole Jones and no warming thing).
78697. Andy Skuce at 04:42 AM on 25 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       

       Added: There's a good Scientific American article on the Geoid that's worth a read.

       Moderator Response:

       [DB] Updated link to SA article.

78698. Dave123 at 04:38 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       Kudos to Tom Curtis for driving home the message of the video. The position of the bouy vs annual ice limits and expected timing is why the video is dramatic..although anything with time lapse in it has its own inherent drama...
78699. Paul Magnus at 04:20 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       This is a great article... maybe sKs can do some more like it.. http://www.crikey.com.au/2011/03/09/climate-change-cage-match-abbott-debates-abbott/ Not on topic (cant see where to post NOT posts)
78700. DSL at 04:15 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       aPirate, according to your method, Mt. Everest will be under water in roughly 2.78 million years. Trends are inherently historical. Models are used for prediction. How do you justify using such a simple model (extending the trend line) to predict such a complex event? Arguing from an extended trend line is useless. Get a better analysis--preferably one based in physics (unless your physical model actually predicts the second coming of Noah; if so, that would explain a lot about some of the arguments you've made).

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