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Comments 78751 to 78800:

78751. 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.
78752. 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.
78753. 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!
78754. 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.
78755. 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.
78756. 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
78757. 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.
78758. 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.
78759. 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.

78760. 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?
78761. 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.
78762. 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.
78763. 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.
78764. 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.
78765. 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.
78766. 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.
78767. 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:
78768. 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.
78769. 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.
78770. 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.
78771. 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."
78772. 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.
78773. 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?
78774. Composer99 at 07:25 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       Climate4All: {citation needed}
78775. 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....
78776. 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.
78777. 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.....
78778. 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).
78779. 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.
78780. 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.
78781. 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.

78782. 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.
78783. 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.
78784. 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.
78785. 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.
78786. 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).
78787. 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.

78788. 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...
78789. 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)
78790. 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).
78791. Andy Skuce at 04:08 AM on 25 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       John Russell: The melt water from the ice sheets is distributed (to a first approximation, it's always more complicated!) evenly over the entire ocean surface of the world. The reason the planet's shape changes is because the ice at high latitudes is removed. Simply adding water to the oceans from some other source wouldn't necessarily increase the oblateness. The shape of the Earth, referenced to sea level, the Geoid, is not a smooth or simple geometric surface but is actually lumpy, due to gravity variations arising from the uneven distribution of density in the Earth. It would be harder to visualize the oblateness of the Earth if there were no oceans but the shape of the geoid is a useful and measured quantity, even in the center of continents. Other planets and the Moon (in fact, any body that spins on its axis) also have known oblate shapes, despite having no oceans.
78792. Rob Honeycutt at 02:45 AM on 25 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       Kevin... Thank you for stopping in to make comments and clarifications. I just want to quickly say that we know you take a lot of fire out there in the media but your hard work and dedication to the science of climate change are greatly appreciated by all.
78793. Kevin Trenberth at 02:29 AM on 25 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       As has been noted, I have been traveling, and I have quickly gone through the 67 comments. A few responses follow. There seems to be some confusion over Fig. 3. This represents the total net radiation from CERES EBAF and so it does include effects of clouds. It is not just the clear sky component (that is a lot more uncertain). Ironically the working definition of "clear sky" used in the community excludes clouds but includes aerosol. Since aerosols affect clouds (the indirect effect), I find this rather unsatisfactory. Still it does not affect things here. There is discussion in the comments of the supposed finding that increasing aerosol (pollution) from China may be the explanation for the stasis in surface temperatures and I do not believe this for a moment. Similarly, Jim Hansen has discussed the role of aerosol as a source of discrepancy. However, the radiation measurements at the top of the atmosphere from satellites (CERES) include all of the aerosol effects, and so they are not extra. They may well be an important ingredient regionally, and I have no doubt they are, but globally they are not the explanation. How did the imbalance occur (comment 2) can be seen from Fig 3 broken into ASR and OLR (not shown here). ASR increased, suggesting fewer clouds as occurs in La Nina over the tropical Pacific, but OLR decreased. The latter seems to be mainly a temperature signal: colder conditions mean less radiation to space. This is often a complex relationship because the biggest variations occur in the Tropics and there is typically a large offset in OLR and ASR signals in association with variations in convection that largely relate to albedo effects being offset by the radiation to space from tops of clouds. Thus fewer clouds means more ASR and more OLR (since the radiation to space comes from warmer lower levels). But that works only in the tropics. At higher latitudes OLR is dominated by surface temperature effects. Comment 17 asks about "back radiation" which is really "downwelling radiation" that is the downward component emitted from the atmosphere in all directions. Clouds, water vapor, and all the greenhouse gases play a key role and the emissions correspond to the temperature of the air. For clouds, the key temperatures are the cloud top temperature for emissions to space and the cloud bottom temperature for emissions back toward the surface. An important point is that to understand the energy flows (which include radiation), the full three (or really four) dimensional structure of the atmosphere is needed, and the simple Figure 1 does not show the vertical structure of temperature. In response to 26: yes melting permafrost can take up some energy but the amount turns out to be very tiny. The last topic I'll touch on is the ocean heat content (OHC). A couple of references were made to the von Schuckmann and Traon paper, which was nice to see, but has some flaws. For instance the data down to 2000 m in the ocean have increased since 2002 and since the beginning of that analysis, yet their error bars are constant. New analyses will be of considerable interest and are underway. I discussed this in this article here in Nature: Trenberth, K. E., 2010: The ocean is warming, isn't it? Nature, 465, 304. http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/NatureNV10.pdf ENSO involves a redistribution of OHC and losses to the atmosphere in the latter part of El Nino, and gains during La Nina, so this is internal to the climate system, not external (comment 31). The southern ocean is clearly playing a role (comments 48, 49)in taking up heat and mixing it deep, even though the magnitude of the observed warming is small. But the data are fragmentary and unsatisfactory in many respects. Nonetheless, the southern oceans, while playing some role, are not the main place where the heat goes in our model. We have a paper submitted that describes and documents that in more detail so it is premature to go into detail here. A nice paper is in press in GRL by Palmer et al (UKMO) using two Hadley climate models that details the relationship between SST and OHC to different levels in their model. Going all the way to the bottom accounts for all of the OHC but the upper OHC in the top 300 m and the SST (which relates to that) are not always good indicators of total OHC. So they also find that energy can go missing into the deeper ocean, and moreover the main phenomenon in their model associated with this is La Nina. [This latter point is not in their article]. The bottom line is that the ocean plays a major role in climate and especially in interannual and decadal variability, and a lot more will be written on this topic. Maintaining an adequate observing system is extremely important. Kevin Trenberth
       Response:

       [DB] Hot-linked URL.

78794. John Hartz at 02:21 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       I have alerted the three authors of the paper summarized in this news release about this posting. They may choose to chime in on this comment thread.
78795. John Hartz at 01:43 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       @Apiratelooksat50#2: Exactly which figures do you disagree with? Have you read the published paper that this news release is summarizing?
78796. muoncounter at 01:41 AM on 25 July 2011
       Rising Oceans - Too Late to Turn the Tide?
       pirate#2: "I disagree" Let's see, for this study, UA team members analyzed paleoceanic records of global distribution of sea surface temperatures ... then compared the data to results of computer-based climate models simulating ocean temperatures ... The team found that thermal expansion could have contributed no more than 40 centimeters – less than 1.5 feet – to the rising sea levels during that time ... That means almost all of the substantial sea level rise in the Last Interglacial must have come from the large ice sheets For the dissenting 'study,' we see a graph covering an 18 year period and an extrapolation to 89 years. Yeah, I'd say that's disagreeable.
78797. muoncounter at 01:24 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       pirate#4: "it is designed to play on emotions ... " Odd. An emotional response to the title of an article? Rather than what is described in that article? "... and imply something other than a natural cycle that occurs annually. " That 'natural cycles' gambit is more of a dead-ender now than the past few times you've trotted it out. It is on you to substantiate those 'cycles'. For example, how does the July 14 Icelights fit into a natural cycle? So far this summer, Arctic sea ice has been melting at a record pace. ... ice extent is currently lower than it was at the same time in 2007, the year that went on to shatter all previous records for low ice extent in September There's something about living more than 2 standard deviations below the mean that just ain't natural. But no doubt you can rationalize that away. And the subtitle to Icelights, 'Your Burning Questions About Ice & Climate,' was surely designed to play on your emotions.
78798. Bob Lacatena at 01:02 AM on 25 July 2011
       Milankovitch Cycles
       To elaborate on scaddenp's comment at 17 (not sure if this has already been clearly stated elsewhere in the thread), my own understanding is that current theory states that the changes in insolation do not actually affect much themselves except to shorten/cool NH summers at the onset of a glacial, or to lengthen/warm NN summers at the onset of an interglacial. This warming is enough to cause a slow (meaning a lot slower than what we're doing to the Arctic) advance or retreat of northern hemisphere snow cover. Because of the amount of land in the NH, this results in a substantial change in albedo, which of course drops temperatures, and advances/retreats snow cover further. The drop in albedo further results in other feedbacks, primarily CO2, through things such as vegetation changes and ocean temperature changes. These, of course, evoke further feedbacks, as is well described by current climate science literature. The fact that changes in TSI are so minimal, and yet the glacials/interglacials occur, is an important clue that climate sensitivity is high. Ultimately, these effects all combine enough to cause the level of climate change required. The main problem I've seen in the literature is in trying to identify the cause/mechanism behind what appears to be an abrupt release of CO2 (which is both detected in ice core measurements, and also required for the degree of climate change seen) early in the termination of a glacial period. There's a lot of literature to be found just by searching for "CO2 glacial termination."
       Response:

       [DB] Fixed original text.

78799. Tom Curtis at 00:51 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       Seeing apirate wants to play silly-buggers, I think it's appropriate to look at the mean sea ice extent for September as shown here (pink line): The interesting thing is that the location of the buoy from which the video was made is well inside that pink line. So in late July of 2011, it is already melting back beyond the mean September sea ice extent for 1979 to 2011. This can be confirmed in the picture below of sea ice extent on July 17th Apirate may want to attribute the fact that the summer melt has already reached a stage it normally takes two more months to achieve simply to an annual cycle. Others may suspect, at least a little bit, that if the annual cycle was the sole factor involved than this current melt extent would be the July mean rather than near the September mean.
78800. Neven at 00:10 AM on 25 July 2011
       Gripping video of Arctic sea ice melting away before your eyes
       apriatelooksat50, the video is gripping, if you're interested in this kind of stuff. And it does simply show ice melting in the Beaufort Sea. Nothing wrong with that title, unless you're having a hard time thinking things through.

       Arctic sea ice melting in the summer is hardly news. I am not saying that annual Arctic sea ice extent has not declined.

       Indeed, Arctic sea ice has declined in summer. So fast even that it is very big news. Unless you don't want it to be news, of course.

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