Recent Comments

Prev  1434  1435  1436  1437  1438  1439  1440  1441  1442  1443  1444  1445  1446  1447  1448  1449  Next

Comments 72051 to 72100:

72051. Wade Smith at 08:42 AM on 20 October 2011
       Sea level rise predictions are exaggerated
       Now remember, I'm not an expert and don't claim to be. I'm just johnny come lately looking at some data and stuff... Now Sea level rise from 1995 to 2005 was around 30mm to 40mm, depending on who's data you believe, and 20CM in the last several decades of recorded history. Thermal expansion of water suggests we should get about 7cm of sea level rise per degree celsius of temperature increase of the ENTIRE HYDROSPHERE. We have it that Sea Surface Temperatures average has increased by about 0.9...but that is just the SST, that is not the average of the entire water collumn... Which is what is misleading about this. The oceans do not top heat very well. The majority of the depths of the oceans is in total darkness, and most of the heat concentrates near the surface, sort of like your swimming pool, the top few inches are hot, but the lower levels are cooler. So in reality, almost no thermal expansion actually happens unless you heat the entire water collumn by an average of 1C, but to do that, you'd really need to heat the surface temps by an average of about 2C or 3C, if not more than that, to make up for the fact hot water doesn't mix well in the deep oceans. At any rate, the amount of heat required to heat the hydrosphere by the average 1C to cause 7CM of thermal expansion (as vertical sea level rise) is 4200 * 1.4*E21 Joules. This is equal to 391 days worth of the entire solar constant, if all energy went to nothing other than raising the temperature of water, which is completely ridiculous and we obviously know isnt happening. Anyway, by the time you take this into consideration, and SST has only risen about 0.9C average in the past century, then thermal expansion is probably no more than like 3cm or 4cm, but whatever. Let's give them 7cm from thermal expansions, just for the sake of argument...that's still leaves about 13cm from melting glaciers and ice caps during the modern records, and what? At least 20mm to 30mm in the past 10 years from melting Greenland and the West Antarctic sheets alone... If I calculate that out based on approximate surface of the ocean, I get a volume of 7.6485E12 meters cubed. This is 7648.6 kilometers cubed worth of ice melted in the past 10 years. Keep in mind, I'm just using "round" anecdotal numbers. http://www.grinzo.com/energy/2009/09/02/how-fast-is-greenland-melting/ Sn = 120* sum(1 + 1.1 + 1.1^2 + 1.1^3 + ... ... + 1.1^n) 120 being about the "known" annual net melting of 2001... I got a total, using round numbers, of 2100. Ok, well, admittedly, that's only around 1/4th of the total we need, however, we didn't consider Antarctica is probably melting at about the same rate, and we didn't consider other ice melting and snow packs melting earlier, and things of that nature. If you double it to make up for Antarctica probably melting similarly, that gives around 4200. Then double it again to make up for the fact field researchers and satellites may be missing some of the action when looking directly at the glaciers, (but the sea levels catch all whether or not man does).... So I explained at least half the Sea level rise of the past decade as definitely being from "known" ice cap melt in Greenland and Antarctica, and assume field researchers and satellite interpretations have missed as much as half of the losses.... Even if I'm off by 50% one way, or 100% the other way, it only makes a 5 to 10 year difference in the long term projection of when Greenland totally melts... At any rate, it shows that the Sea level rise data relates very, very well, almost exactly 1 to 1 with then measured melting rates of Greenland over the past 10 to 20 years....
72052. skywatcher at 08:40 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Eric, I seem to recall Tamino doing a post about empirically determining cyclic behaviour in a timeseries - it is not as easy as some think, and more obviously hard if the proposed cycle wavelength is a relatively large fraction of the dataset length. Can't find it now, but this and this may be interesting for looking at extracting periodic behaviour. Dikran's point about physical mechanisms is also very relevant. I came across the following chart at the end of another superb post of Tamino's: Dr Pielke and others may be interested in reading it. It shows "... trends over the most recent 10-year period. Here they are (plotted in blue), compared to the trend over the entire time span common to all data sets (plotted in red) [1979-end 2010 when posted]" None of the 10-year trends (to 2010) was significant, yet all the 30-year trends are not only significant, but agree closely, within error. I was still most disappointed that Dr Pielke failed to answer the direct questions about the surface temperature data. I'm also disappointed in his attempts to divert via suggesting that the heat content of the climate system can be determined on a yearly basis. That would be true if we were monitoring every possible heat sink on the planet to a high degree of accuracy, deep oceans included, but we are not (though this is improving). His chosen measure does not cover all locations where Joules go, and is thus no better than anyone else's measure of global warming, despite his protestations to the contrary. His focus on 0-700m surface ocean, avoiding the visible warming deeper in the ocean, is a cherry-pick, just like his focus on 2002 to present for the surface temperatures.
72053. Bob Lacatena at 08:10 AM on 20 October 2011
       Sea level rise predictions are exaggerated
       11, Wade, Hansen argued your case in Paleoclimate Implications for Human-Made Climate Change (2011). The bulk of the paper tries to compare current events to the last time this happened (although over much longer time frames) in the Cenozoic, Holocene and Pliocene, when sea levels rose 15m to 25m. You would be most interested in section 6, however, on sea levels, where he argues that the increase is probably not linear, but instead with a potential doubling every ten years, with all of the nasty implications that you yourself have tuned into.
72054. Wade Smith at 07:39 AM on 20 October 2011
       Sea level rise predictions are exaggerated
       Hey, At first, I was a GW skeptic, but then in the past year or so, I've really begun to study this data, and I'm convinced now that not only is GW real, but it's probably worse that what has been predicted. I'll just link to a few obvious sources for paraphrase and reference of data. http://www.grinzo.com/energy/2009/09/02/how-fast-is-greenland-melting/ http://nsidc.org/arcticseaicenews/ http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html Ok, anyway, what I noticed several months back is the simple fact that each year you have a net melting, whether sea ice or land-locked ice caps, it would be obvious that the change in albedo of that area of "net melted ice" should "pay" for it's own melting within a certain number of years. I assumed it would be an exponential, and was playing around with a bunch of different numbers for the exponential growth, but I didn't know exactly what numbers to use, until a few weeks ago. Suffice it to say that one of the articles I linked to above shows how the five year average rate of melting of ice in greenland is doubled in ten years. As it turns out, just recently, it was discovered that the rate has actually quadrupled in about 10 years! Well, what curve does that follow? And is it related to the PIOMAS data? Well, yes it is! Greenland and Sea Ice are treated as two seperate entities, but they follow the exact same curve: A power series. IN the article above, "Lou" mentions what appears to be a linear progression for average annual net melting of Greenland as: 200, 220, 240, 260, 280. But these were not measurements, these were his rough estimates based on 5 year total loss data, going all the way back to 1996 @ 96km^3 to 280km^3 in 2008. Well, what I would suggest is this is not a linear function. The numbers appear linear because he "reconstructed" the annual rates by just assuming it's increasing, but the increase isn't linear, it's exponential. In 12 years it increase from 96 to 280(or 300), but assuming this is exponential increase, then we have: 280/96 = 2.916 12th root of 2.916 = 1.0933 we have the form: c*n^x x = time (delta) in years. n = 1.0933 c = 96 (initial melt rate) Now if we actually plot these numbers for whole number X, starting at 0: 96, 105, 115, 125, 137, 150, 163, 179, 195, 214, 234, 256, 279, 300,..., c*n^x.... is very close to linear: 100, 120,140,160,180,200,220,240,260,280,300... You can see how if you were trying to "post-dict" this from field observations with normal noise in raw data, you might mistake this for a linear relationship due to errors in instrumentation, rounding, etc. But what you find with the Piomas sea ice data is the same. If you take the 5 year running average of the data (the 10 year running average is too "back heavy" to be useful,) and starting from the last time there was a volcanic rebound in the 5 year average data: 5 year running average of Piomas volumetric sea ice data, starting with 1990: 90 14.86 91 14.38 92 14.32 93 13.78 94 13.58 95 13.08 96 13.12 0.04+ 97 12.78 98 12.64 99 12.10 00 12.06 01 11.78 02 11.28 03 11.02 04 10.82 05 10.46 06 9.82 07 8.96 08 8.34 09 7.74 10 6.78 11 5.84 Now, this is no big deal, its an exponential, which they calculated on the site, but the kicker here is that the 5 year average is itself "back heavy" by about 3 years. If you put this data in a graphing calculator and do a regression, you'll find that the five year running average is zero within 8 years. (I interpret negative numbers on this curve after the "0" as additional net losses to Greenland.) But what I noticed is you can smooth out the raw data from Greenland and the Sea Ice by simply noticing that they are the same thing, and adding the net losses together. The average net annual loss in sea ice in the past 5 years was: 9000 - 4300 = 4700 4700/5 = 940km^3 The net annual loss from Greenland is currently "somewhere" around 300km^3. 940 +300 = 1200km^3 annual loss. If you then assume the entire ice mass is following about the same curve, you can start with 1200 as the coefficient, c, above, to run a series to see the rate of melting. After all, the cumulative energy which is currently going into melting Sea Ice will have to go "somewhere" once the Sea Ice is melted. The obvious place is the ice on Greenland land mass... Since I know from the data that the exponent is certainly somewhere between 1.072 and 1.15, you can calculate the minimum and maximum times of Arctic Sea Ice melt (5 to 8 years,) and the minimum and maximum times of Greenland meltdown... Yes, I've done this, and God help us all, it's much faster than anyone publicly claims. NOw to show how well this works predictively, we can take the piomass data and pick two "good", adjacent data points which are not corrupted by the volcanic rebound peaks (or alternatively pick two adjacent 5 year running averages...) Take the difference between 86 and 87: http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html 15.9-15.2 = 0.700 (thousands) Now, let's pick an exponential, say 1.15, a big one, and project the curve forwards. 2011 - 1987 = 24 years -0.700 * 1.15^24 = - 20.03 Well, you say that's too much? Well, not hardly, we have to add back the volcanic rebounds of years following major volcanoes: 86 1.4 (columbia) 91 1.4 Pinatubo 94 1.4 (unknownst ot me) 96 2.5 (Monsurat) 01 1.2 Hekla 07 0.6 Furnas (I think) Total: 8.5 Now -20 + 8.5 = -11.5 And of course, This is statistically close to the real data set's end: 15.9 -11.5 = 4.4 1986 minus 1.15 exponential projection to 2011, and adjusted for volcanic winter rebounds... Very close to the actual 2010 and 2011 data of 4.4 and 4.3 respectively... Therefore, 1.15 is probably the correct exponent when you factor out volcanism, but the real exponent with volcanism is a bit lower than that... This suggest Greenland is melting much, much faster than anyone publicly claims, as in possible total meltdown within the century, and that is NOT an exaggeration... To top it all off, World population growth is 1.1% per year, and then you figure all the countries modernizing, the net CO2 production will probably increase at a rate of about 22% per decade for at least the next 2 or 3 decades...Which gives something link another 90PPM CO2 by 2040, or around +57PPM by 2030...
72055. Bob Lacatena at 07:39 AM on 20 October 2011
       Newcomers, Start Here
       128, Charlie, You make a lot of fair points, with only one quibble (people will likely start to feel climate change in unpleasant ways withing 30 to 50 years, not 100, so if you are a man in his fifties, your children will likely suffer directly, and if you are in college yourself then you will suffer... not greatly, perhaps, depending on your luck, but it will begin to intrude on lives in nasty ways before 100 years pass). But you identify three problems. The first is that the science is too complex. True, but unfortunately it is what it is. This is not an issue in medicine, where you don't understand everything about how the human body works, but you trust the doctor. Or law, or finance, or anything else. You trust someone who does know. (See this article for more.) Which leads to the second problem, which is that unlike your personal health or your asteroid problem, there is a group that benefits financially from CO₂, no matter how dire the effects on the globe and humanity, so they are actively working to confuse you. The science is only that complicated if you have to get into it knee deep, which is what you have to do because the denial industry tries to fabricate 10 arguments for every piddling detail within the science. But your third problem, the idea that people need a shock effect that they can see and relate to to actually take action... that is, sadly, a part of human nature, but one for which there is no solution. Climate change is slow. Natural climate change takes thousands to millions of years. Anthropogenic climate change is still going to take more than a human lifetime to begin to show the true peril it represents. There's no getting around that. The thing is, if you jump off of a really tall building, it's going to be a while before you feel the effects. Until then, it's a really fun ride. But that doesn't mean you do it. Human intelligence is founded on being able to understand and predict events. It's based on knowing that if you stick your hand in the pretty red flickering light (i.e. a fire) it is going to hurt. So that's really where we stand. People need to think. They either need to learn the science (properly, not by believing the first bit of comfortable denial tripe that they hear) or else to trust the experts that do know. The third course... failing to learn, but distrusting those who are qualified in favor of those who tell you what you want to hear (and what they want you to think) is an unfortunately common aspect of human nature, but in this case it is one that is going to define our future. The most you can do as an individual is to learn as much as you can, figure out whom you can really trust, and to try to convince as many other people as you can to do the same, and to recognize that it is important. It may not seem like it now, but eventually we're going to hit the pavement, and the only way to stop that is to have never jumped off the ledge in the first place.
72056. scaddenp at 07:32 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Eric, you might like to review the statistical analysis at tamino on this approach.
72057. adelady at 07:31 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       MA Rodger "With large increases in the rise due to melting land ice, there is a limit to the rise because of the latent energy required to melt the ice..." But that's not true for collapse of ice is it? There are places where a substantial incursion of rising waters beneath an area of ice could convert land ice into a floating (or near enough for these purposes) ice shelf. At which point the ice merely has to displace water rather than become water to affect sea level. No latent energy required.
72058. Bob Lacatena at 07:20 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       11, fydijkstra,

       ...because there are many other factors that influence global temperature...

       True, but there are not many factors at all that influence global climate over the time frame we are discussing (the next decades to hundreds of years) and to the degree that we are talking about (i.e. raising temperatures to their highest levels in 10,000 and maybe 150,000 years). There is nothing that you can name outside of anthropogenic CO₂ that is going to melt as much ice and expand as much water as we are now.
72059. Michael at 07:13 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       The Carbon Cycle and the residency time of CO2 in the atmosphere is what will ultimately determine Equilibrium sea level rise. If we peak at 540 ppm CO2 in the 21st Century there will be a minimum of 380ppm in the air 1,000 yrs later. This level corresponds to the Mid Pliocene when sea level was 15 meters to 25 meters higher from average global temperature ranging 1C to 2C warmer than present. Anyways the CO2 maths are pretty simple - the carbon cycle is the key - and the key to understanding it is ocean chemistry. All the other influences people get caught up with come out in the wash on these time scales. So yes 15m to 25m sea level rise is the ultimate consequence of the next 20 years CO2 emissions. More details on www.carbonvirgin.com
72060. John Hartz at 06:59 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       @fydijkstra #11: You assert: "The basis of this whole story is the assumption that there is a straight relationship between the emission of greenhouse gasses and global temperature." Where in the underlying published paper is this assumption stated?
72061. fydijkstra at 06:48 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       The basis of this whole story is the assumption that there is a straight relationship between the emission of greenhouse gasses and global temperature. We all know, that such a relationship is highly uncertain. This approach is far too simple, because there are many other factors that influence global temperature. Most of these factors cannot be predicted at all. The only factor that can be predicted with some certainty is the emission for the coming half century. Trying to predict sea level in the next 500 years, with only partial knowledge of one of at least 5 determining factors during that period, is the same as looking into a crystal ball. Some nice ladies on a fancy fair can do the same.
72062. Charles of the moderate consideration at 06:25 AM on 20 October 2011
       Newcomers, Start Here
       This is my first posting. I am not a scientist. I'm deeply committed to the seriousness of Climate Change and would like to add my weight but I am drowning in the science. I think it is the very complexity of the science in this debate that keeps it from being taken as seriously as it needs. I think we regular folks need an attention getter, 'an asteroid', figuratively speaking. Please indulge me a moment. As I have read the pros and cons from so many informed persons, it is apparent that one needs more education in climate science than I possess to follow the debate at ground level, so to speak. But like many persons, who I assume the science community would want to reach, I possess a logical mind. If higher-end estimates of Global Warming prove to be true, I think this would constitute the most significant challenge mankind has ever faced. How does the average person get past the science and search for the truth? Too many still feel helpless; that whatever climate change there is, is simply a natural fact of life on earth, which we will all have to live with, but can't alter. And many are counted among the millions who still believe that global warming is untrue or a 'hoax'. The debate rages even after the results are in and scientists have made their point. Its confusing. So I try to imagine a parallel scenario, easier for my limited scientific mind to grasp. A poor analogy perhaps, but let's say tomorrow, a gathering of the world's leading astrophysicists announced that after ten years of examining the data, there was a 90% probability of earth's collision with a one-mile-wide iron asteroid in a hundred years. The debate would be different. For one thing, it would be short, not decades long. We'd be checking the data, doing our homework as individuals and families, and establishing a global consensus. We'd be listening to out top scientists and mathematicians. We'd have less patience with unqualified opinions that confuse, and the audience these persons would draw would shrink dramatically. We would get on with what mankind might do to mitigate the problem before it shows up on our grandchildren's doorstep at 27,000 MHP. Some of the upper-end estimates of global warming during the next 100 years are barely less onerous to humanity than my poor asteroid example. So what's the problem? Logic might answer that question as well. On one side we have a dedicated group of Climate Scientists who are telling us what their research indicates. Collectively, they have limited financial resources, but they do have education, dedication, and years of hard won facts. Are they perfect? No. But are they right to a reasonable, logical certainly? Yes. On the other side of the fence, we have the largest man-made entity on this planet, the Fossil Fuel Industry. And in their corner, we also we have the Auto Industry, the Electric Utility Industry, and most Governments. If this were a prize fight, I know where my money would be. Logic tells us that money is what is controlling this debate. An unlimited supply of money to recruit, and finance, and confuse people like me who are just trying to sort out the truth and try leave my grandkids a reasonably civilized world. I, after all, helped to create the problem. So I look at the the facts (or non facts) of climate change logically. Some say the world is too big for man to have a significant effect on our climate. Logic tells us that mankind has developed the technical capability to do just that. Few if any, for example, argue that the climate would change if mankind engaged in all-out nuclear war. That's probably why we haven't done it yet. Logic points to many aspects of this issue which are measurable. We may argue the methods somewhat, but 2% is not 1% and words can't change that, no matter the money paid and the credentials touted. We can measure CO2 over time. We can measure temperature and sea level changes. We can input new data from the past by analyzing Ice-core samples and input new paleoclimatological data from past millinea. And we know carbon chemistry. Even I know if you burn fossil fuels, CO2 is released. If you burn a little, the earth stays in a state of relative balance. If you burn a lot, CO2 increases. We understand the physics of a greenhouse gas. CO2 and methane are biggies. The more greenhouse gases in the atmosphere, the hotter it gets. And logic helps us sort out 100 years of 'the hottest year on record', or 'the strongest storms', or 'biggest floods'. The earth is talking to us and its telling us the climate is changing, and it ain't linear. Maybe we are, after all, just like the frog in the 'slowly heating pot of hot water' experiment. Maybe, even if we're looking at a 6 degree ambient atmospheric temperature increase, it happens so slowly in any one persons experience, that its just too hard to focus and 'suffer now to save later'. 'They' say the frog just sits there and slowly boils to death. Is that us? I think we need an asteroid to get everyone's attention. What would that be?
72063. Karamanski at 06:22 AM on 20 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       Since the mechanism by which greenhouse gases heat the ocean is through slowing the escape of heat from deeper depths by heating the "cool skin" layer , wouldn't that mean that the amount heat accumulating in the oceans is larger than the amount of heat being trapped by greenhouse gases in the atmosphere?
72064. CBDunkerson at 05:44 AM on 20 October 2011
       Hurricanes aren't linked to global warming
       Looks like DB came to conclusions similar to what I posted above after skimming the two papers. With the background on what is being claimed it seems like 'skeptics' are just taking random papers on hurricanes and grossly misrepresenting what they say. Either that or they're really bad at reading comprehension.
72065. Hyperactive Hydrologist at 05:40 AM on 20 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       As far as I am aware temperature dominates in lower latitudes and salinity in higher in relation to buoyancy. I don't think diurnal effects have much impact on surface waters due to the inertia of water.
72066. MA Rodger at 05:24 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       SteveFunk @8 The rate of any rise caused by a warming will slow with time after the warming stops. Globally, the rate of sea level rise was 1mm pa in 1900, 3mm pa in 2000. Whatever comprised the 'little ice age' & any resulting sea level rise have been superceded by more recent warming.
72067. Micawber at 05:22 AM on 20 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       This post, for me, appears to ignore one primary property of seawater and that is its salinity. Both salinity and temperature determine buoyancy. Resulting density imbalances lead to vertical thermohaline adjustment. I have always assumed that diurnal warming leads to evaporation with water mass loss in the surface skin. We would expect both temperature and salinity to increase during the daytime radiation. At night, surface cooling through radiative heat loss should allow the increased salinity to create a density gradient down which the surface waters travel to reach an equilibrium depth. In the tropics evaporation is reported to be of the order of 2m per year. But we still get evaporation as evidenced by coastal fogs in more poleward latitudes. Has there been any observational work on Tangeroa of these temperature and salinity gradients? I am very interested in near-surface dynamics in the ocean and its role in distributing heat and salt.
72068. Albatross at 05:18 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       SteveFunk @8, An interesting question, but most likely not. See how those curves flatten rapidly and are virtually flat from 2400 onwards (assuming the forcing for the warming is reduced)? The LIA peaked in the late 1600s (so over 300 years ago) and the graph below suggests that the event was not associated with any notable decline in sea levels because of increased glaciation, although the rate of increase did appear to slow somewhat during that time. Either way, any lag in the system from events back then would currently certainly not be described as "significant". [Source] The fact is that our inaction now is going to affect the planet and its inhabitants for hundreds of years to come, perhaps even for millenia. We cannot change the past and/or natural variability, but we can control emitting GHGs. This paper underscores the importance of taking prompt action.
72069. SteveFunk at 04:41 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       If it takes sea levels 500 years to reach equilibrium, wouldn't a significant proportion of the current rise be due to the forces that ended the little ice age?
72070. itscoldoutside at 04:36 AM on 20 October 2011
       Hurricanes aren't linked to global warming
       @DB, thanks! (Note to web editor: Perhaps an index listing often quoted papers would be helpful, My attempts to search for information on this here weren't exactly fruitful). @CBDunkerson the first paper, for instance, is being used to argue that there has been no increase/change in weather severity. Presumably it's been taken out of context; I'm looking for some context.
72071. Hyperactive Hydrologist at 04:14 AM on 20 October 2011
       El Niño: Unaffected by climate change in the 21st century but its impacts may be more severe
       Stevo @ 11, As far as I know ENSO has very little influence on the UK and intensity of multi day (5 and 10 day) rainfall events appears to be increasing especially in the west Extreme Rainfall UK. Also there was an interesting event in Cumbria, 2009 which broke many records. CEH paper MET Office records Rainfall was exceeded by almost 25% over previous records at the Seathwaite raingauge. Although it is suggested that only 5-7% can be attributed to climate change.
72072. Andy Skuce at 04:13 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       One additional consequence of rising sea levels will be that maritime boundaries (defining Exclusive Economic Zones, EEZ) between states will also shift, since they usually rely on equidistance from coastlines. See this Nature article, subscription only, unfortunately. This World Bank article (pdf) states:

       There are no provisions that potentially “fix” the outer boundary of the EEZ, the contiguous zone, or the territorial sea. Many scholars have therefore considered the legal and physical boundary of these maritime zones to be ambulatory.

       Gotta love that legal jargon.
72073. Dikran Marsupial at 03:44 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Dana Hicks wrote "The answer is that the short term trend is statistically significant from other short term trends witnessed recently." O.K., if you claim that it is statistically significant, then state the assumptions and give the calculation of the p-value that demonstrates the difference is statistically significant.
72074. Hyperactive Hydrologist at 03:28 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       Vulnerability in coastal regions will increase substantially by the end of the century. Not only due to sea level rise but because of an increase in population in coastal regions. We may see cites such as New Orleans abandoned. As sea levels rise adaptation becomes increasingly difficult and expensive. Hopefully the rate of sea level rise will be at the lower end of the predictions. This will allow more time to implement adaptation strategy and give existing infrastructure a longer lifetime before it needs upgrading. Planning restrictions in high risk areas will be important to minimise risk.
72075. Dikran Marsupial at 03:19 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Albatross I am a big believer in the "golden rule" (do unto others as you would have them do unto you" (or words to that effect). As a scientists, if I were wrong on an important scientific issue and having difficulty understanding the problem, then I would be extremely grateful to someone who patiently carried on trying to explain my error however long it took, if that was what was required for me to see where I was going wrong. I'd be even more grateful to them for doing so had I not behaved as well as perhaps I should - we are all only too human. While Prof. Pielke responds to questions in a manner that allows alternative explainations of the statistical issues there is value in continuing. However it would help if direct answers were given to direct questions.
72076. John Hartz at 02:18 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       @DanielOlivaw #4: In my opinion, the take-way from this study is the following statement by Aslak Grinsted: "Even if we stabilize the concentrations in the atmosphere and stop emitting greenhouse gases into the atmosphere, we can see that the rise in sea level will continue to accelerate for several centuries because of the sea and ice caps long reaction time." The accuracy of the model forecasts is of secondary importance to this basic finding.
72077. Bernard J. at 02:11 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Albatross. Such argument is "very troubling and underwhelming" indeed. It's the greasy pig version of discourse, and the very antithesis of real scientific discussion. I also agree with your preceding sentiment. If Pielke Snr consistently chooses to continually evade the fundamental points of this whole exchange, then I too will disengage from chasing his tail. It's been an interesting exercise neverthless, even though I only chipped in my $0.02 at the end. Still, I will walk away from this discussion with no shame. I wonder if Pielke Snr could genuinely do the same thing...
72078. Albatross at 01:54 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Bernard J@106, Thank you for taking the time (and it does take time to weed out the details and chronology) to very nicely demonstrate the goal post shifting and strawmen arguments that we have all had to deal with on this and other threads by Dr. Pielke. I find his behaviour and arguments about the science very unfortunate, and as a fellow scientist, very troubling and underwhelming.
72079. Albatross at 01:48 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Dikran, Daniel, Dana, Tom C., and readers Dr. Pielke says, "I will be signing off with this thread here, but will have several questions for SkS in the next day or so on my weblog that I will invite you to discuss on SkS." Given that Dr. Pielke has continued to evade answering pertinent and reasonable questions put to him, his strawmen arguments, his shifting of goal posts, his propensity to misrepresent our position, his questioning the scientific and statistical understanding of the knowledgeable posters here, why on earth would we continue with this "discussion" or take more of our time to answer questions posed to us by Dr. Pielke? He has not offered us the same respect and courtesy, and quite frankly at this point I have no interest in engaging in what seems to be an endless faux debate and arguing in circles. With that all said, I am heartened that Dr. Pielke agrees that we need to reduce our GHG emissions, and I look forward to Dr. Pielke providing policy makers with unambiguous and crystal clear messaging on that aspect both on his blog and when appearing before government.
72080. DaneelOlivaw at 01:32 AM on 20 October 2011
       Sea levels will continue to rise for 500 years
       I've saw this but I don't know how to interpret it. Are we comfortable using models to project 5 centuries into the future? And even more important, is it *that* relevant? 500 years is a looong time and there could be a lot of changes in natural and anthropogenic forcings, right? So, even if the projections were accurate, I'm having a hard time putting this results on the proper context and decide how meaningful are they.
72081. DanaHicks at 01:32 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       It apears that some people are having difficulty with short term trends. The recent trend (let's choose 10 years for simplicity) is not significantly different form zero. That is different than saying it is not significant. There have been other recent periods where similar trends have occurred (winter 1987-1997, 1977-1987, and pre-1980). There have also been 10-year periods with a statistically significant warming trend (1973 or 4 - 1983 or 4, and any 10-year period starting from 1990 - 1994). There was a 10-year period from the end of 1981 - 1991 which falls just short of significance. The answer is that the short term trend is statistically significant from other short term trends witnessed recently. The more appropriate question would be why are the short term trends different. Some here (on other threads) have alluded to the 11-year solar cycle s affecting the short-term temperature trends. This would seem plausible as the largest 10-year trends were observed ending on 12/83, 9/91, and 3/02. Somewhat corresponding with the sunspot maxima on 10/79, 8/90 and 12/01.
72082. barry1487 at 00:59 AM on 20 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       Rob @ 14 - I'd hazard the choice to go with the Charney sensitivity makes sense for a policy document like the IPCC reports. The estimate is better constrained and the feedback processes are 'fast' in that their impact can be felt in decades. If the concern is the rate more than the magnitude of change, then slower feedbacks perhaps don't need so much attention in the IPCC.
72083. CBDunkerson at 00:53 AM on 20 October 2011
       Hurricanes aren't linked to global warming
       Gypster, comments on what? Perhaps you could explain what claims are being made. The Sienz et alia paper is a model study which finds, "In the warmer climate scenario (A1BS) extreme value statistics shows an intensification for all variables." Wallace et alia is a study of the likelihood of hurricanes making landfall between 5300 and 900 years before present, not their intensity. As such, I don't immediately see anything to 'comment' on about these papers in reference to the topic of this post.
72084. itscoldoutside at 00:35 AM on 20 October 2011
       Hurricanes aren't linked to global warming
       These papers are turning up in arguments: Sienz, F., A. Schneidereit, R. Blender, K. Fraedrich, and F. Lunkeit. 2010. Extreme value statistics for North Atlantic cyclones. Tellus A, 62, 347-360. Wallace, D.J., and J.B. Anderson. 2010. Evidence of similar probability of intense hurricane strikes for the Gulf of Mexico over the late Holocene. Geology, 38, 511-514. Comments?
       Response:

       [DB] I have already commented on those papers here.  Please also note the subsequent comments on that thread; all relevant to consider.

72085. Bernard J. at 00:27 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Pielkesr. Just a few points that you might like to consider on your own threads, as you seem to have declined to continue here. First, I said:

       If Pielke Snr has the reference for the work that the planet has in fact not warmed since 1998 (or whenever) I would be most interested to read it.

       to which you replied:

       I have never said that. What I have reported on is the limited warming in the upper oceans in recent years (since 2004) which is clearly evident in http://oceans.pmel.noaa.gov/.

       The thing is, I was responding to your claim:

       However, it is trivial in my view (and does not need any statistical evaluation) to see that the warming has halted, with this being clearly seen in the RSS Figure 7 in http://www.ssmi.com/msu/msu_data_description.html#channels [My emboldened emphasis]

       a claim that was immediately preceded by the statement:

       First, I am NOT saying anything about the effect of the lack of warming in the global-annual average surface temperature since 2002 or 1999 (or whatever start year) on the long term trend. I agree it is too short of a record.

       which (together with the subsequent sentence) would seem to indicate, despite your protestations to the contrary, that you were commenting on surface temperature, and on intervals starting in 2002, or 1999 (or whenever...). Second point, by your own words you say:

       ...the global average temperature trend in the lower troposphere has been nearly flat as shown, for example, in the figure below from the RSS MSU data...There has been NO long-term trend since the large El Nino in 1998. That’s 13 years.

       You are again refering to a temperature record (and to a time period that commences prior to 2004), which is fine, but (to repeat) you say here:

       However, it is trivial in my view (and does not need any statistical evaluation) to see that the warming has halted, with this being clearly seen in the RSS Figure 7 in http://www.ssmi.com/msu/msu_data_description.html#channels.

       Repeatedly, you refer to atmospheric temperature records, but you then go on to make a claim about heat and how there has been no "warming" since 2002. As I, others, and even yourself have indicated on this thread, temperature and heat (and attendant changes thereof) are different beasts. A hiatus in temperature trajectory does not mean that there has been a similar pause in planetary warming. Again, I ask how one can use a statistically insignificant time interval in a temperature record to make a claim about planetary warming - a concept that relates to heat? You say:

       What I presume everyone will agree with is that from 2003 onward, the most appropriate diagnostic to monitor global warming is the ocean heat content changes. If we can agree on that (and since you use the bath tub analogy which involves heat in Joules), than this thread and the others would have been time well spent debating.

       I would agree that it is a part of a suite of parameters with which to monitor global warming, but as many others have pointed out recently here and elsewhere even OHC measurements have their pitfalls (a travesty, I say...!). And yet, you have made a claim that "warming has halted". So, again, upon what empirical basis do you make this claim? How do you know that "there are no more Joules in the climate system" after whatever the statistically-insignificant time period is to which you refer? Third point: how many 9 year intervals in the global surface temperature record show trends "different than the trend for the [23 year] time period [previous]"? What is the implication of the answer to the preceding question?
72086. victull at 00:20 AM on 20 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       Glenn Tamblyn@12 Interesting point you make here: *Also, this mechanism explains well the underlying thermodynamics of 'in-the-pipeline' warming. This is sometimes portrayed as if at some future time all this heat will start 'coming back out' from the oceans. But this doesn't make thermodynamic sense.* All the heat in the land, atmosphere and oceans must be represented in some form - existing water, air and land temperatures, ice melt, air/water vapour content. It seems to me that melting ice takes heat out of the surrounding water and heat should flow to these sinks until all the ice is melted. Would anyone like to explain the effect of sea ice in moderating ocean temperatures? Would sea ice anywhere on the planet prevent the oceans warming until it all melted?
72087. Eric (skeptic) at 00:13 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Dikran, thanks. And sorry, that was Dana (#71), not you I was referring to.
72088. Dikran Marsupial at 00:02 AM on 20 October 2011
       Continued Lower Atmosphere Warming
       Eric (skeptic) If you are looking at a period that is relatively short compared to the characteristic timescale on which the forcings change (e.g. a couple of decades or less), then it is probably O.K. not to subtract out the effects of the relevant forcings. If you want to assert cycles on longer timescales then you need either to show there is a physical mechanism that can plausibly explain the magnitude of effect and/or control for the change in forcings.
72089. Eric (skeptic) at 23:50 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Dikran, up thread you distinguished forcing changes from what you called "natural variations". I presumed that what you meant by "natural variations" was primarily the changes in ocean-atmosphere exchange that result in atmospheric temperature changes on a quasi-periodic basis. If I use that definition I would have to account for solar, aerosol and other forcing changes when I look at the long temperature series (subtract them out). Then I would analyze the periods of the remaining changes to determine the number of years that would indicate a statistically significant change independent of those natural variations. My claim would then be that such a statistically significant change was caused by a forcing change. Does that appear to be valid?
72090. MA Rodger at 23:44 PM on 19 October 2011
       Sea levels will continue to rise for 500 years
       Re The large sea level rise in Hansen & Sato 2011 Hansen & Sato discussed the dual subjects of (i) Whether 2oC global temperature rise would bring seriously bad sea level rise and (ii) The possible speed of that rise. While (i) was presented quite convincingly, (ii) was actually little more than speculation. They developed the idea of a 'doubling time' for accelerating sea level rise, suggesting that the limited GRACE data available (6 year's worth) indicates a 'doubling time' of 10 years. This would imply massive rates of sea level rise by 2100. Present rates of sea level rise are 3mm pa. The IPCC 'most pessimistic' forecast is for an annual rise of 13mm pa by 2100 (which is roughly the average rise during the climb out of the last ice age). With large increases in the rise due to melting land ice, there is a limit to the rise because of the latent energy required to melt the ice, a limit Hansen & Sato 2011 greatly exceed. But if enough land ice turns into icebergs, very large sudden rises can result. As Hansen & Sato 2011 say, past ice ages have ended with multi-metre sea level rise due to much smaller climate forcing than the present-day man-made forcing.
72091. Dana69 at 23:35 PM on 19 October 2011
       Arctic icemelt is a natural cycle
       Hmmm..I have been looking at this issue in more detail and there seems to be some diverse thoughts regarding this topic. First off, The IPCC models tend to simulate a positive phase of the Arctic Oscillation in most of the GCM simulations. Correct me if I am wrong, but don't most positive phases hold colder air in the region thereby slowing the rate of ice loss? Wouldn't this be in direct contradiction to the claim that rising CO2 increases temperature? Also, it seems like the Arctic Oscillation is viewed more as a weather event, and not a climate issue. Meaning, it is much more chaotic, and will not have a diverse affect on climate as a whole and vice versa.
       Response:

       [DB] The AO is what it's name says it is: an oscillation.  Thus, the long-term trend is nil.  But the reality shows that what is happening in the Arctic is indeed unlike a natural cycle and fits the understanding of the Arctic Amplification response to the ongoing warming of the world.  With the ongoing demise of the Arctic Sea Ice cap serving the role of the canary in the coal mine.

       As far as colder air forming a negative response to the amplification, see:

       BOE et.al (2009) "Current GCMs' Unrealistic Negative Feedback in the Arctic", Journal of Climate

       The vertical temperature structure of the atmosphere in the Arctic, characterized by a surface inversion during wintertime, exerts a strong control on the temperature feedback and consequently on simulated Arctic climate change. Most current climate models likely overestimate the climatological strength of the inversion, leading to excessive negative longwave feedback.

       H/T to the Artful Dodger.
       

72092. Bern at 22:25 PM on 19 October 2011
       Sea levels will continue to rise for 500 years
       newcrusader, I agree that they seem conservative, considering some of the recent papers suggesting non-linear ice sheet response. However, the curves only represent the central estimate, without the uncertainty shown except for at 2500. I think the important point to take away is that this sort of modelling helps to demonstrate why it is that we've really only got a decade or two to sort out GHG emissions. Wait another 20 years for more "certainty", and we end up with sea levels that are still rising five centuries from now...
72093. Dikran Marsupial at 22:16 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Eric (skeptic) Fine, but you will need to perform a statistical hypothesis test to determine whether there actually is a cycle in the data where there is no physical theory that can explain the observed magnitude of the effect. You also need to show that the cyclic behaviour is not the result of a coincidence of non-cyclic changes in the observed forcings for which there exist phsyical theories that do explain the observed magnitude of the effect (for instance that changes in solar forcing explain much of the warming in the first half of the 20th century, according to the IPCC WG1 report). If you think cycles can be determined purely empirically then that is only true in the absence of physical explanations, and even then you need to be able to show there is statistically significant evidence for the existence of the cycles, and even then you need to acknowledge that it is only a correllation not a causal link.
72094. newcrusader at 22:12 PM on 19 October 2011
       Sea levels will continue to rise for 500 years
       The estimates here seem very conservative for sea rise. They basically look at a very linear extrapolation. Hansen and Sato see a non linear rise- with as much as a 4-5 meter rise by 2090. During the Eemian interglacial when global temperatures where at best a few tenths of a degree Celsius warmer then today, sea levels where about 4 meters higher then present. With C02 levels reaching double the PI era by mid century, and a 2 degree rise in temperatures over the PI era; with arctic ice 4 decades ahead of IPCC estimates (which will hasten ice melt in Greenland) A 1 meter rise by 2100 seems too cautious.
72095. Eric (skeptic) at 22:05 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Dikran, I'll look into that, but it will take a while. The significance of a trend of N years will depend on the periods of natural cycles and quasi-cycles as compared to N. Those cycles can be determined purely empirically by examining a long data set or semi-empirically by examining the mechanics of cycles themselves (PDO, ENSO, etc) their effect on GAT.
72096. Rob Painting at 21:32 PM on 19 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       Barry @ 4 - Equilibrium Climate Sensitivity, you have me there. Seems a bit of a misnomer. The Earth System Sensitivity approach (as discussed in the Real Climate link) seems better, although harder to estimate.
72097. Dikran Marsupial at 21:27 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Prof. Pielke I would implore you not to sign off before giving a direct answer to the question of whether the evidence for your hypothesis that "the 9 year trend during this time period [2002-present] is different than the trend for the time period [1979-2002]." is statistically significant or not. The readers will indeed make up their own minds about what a failure to answer that question means, and I would have thought that they are very likely to conclude that (i) you know that the answer to this question is "no" (ii) you are unable to admit that the answer is "no" and (iii) you view your subjective interpetation of the observations as being more reliable than the objective statistical testing that are a cornerstone of modern scientific method. As it stands you are likely to do substantial harm to your scientific reputation, which is not something I want to see happen. I would rather we continued with a discussion of the science that aimed to uncover the truth, whatever that truth might be.
72098. pielkesr at 21:19 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Regarding "[DB] "If, for example, there are no more Joules in the climate system after one year" Straw man. In the absence of any significance testing, which you adamently refuse to do, a time series of just one year is meaningless" you do not understand the physics. The heat content of the climate system can be determined on a yearly basis. There is no lag as with the response of the surface temperature trend to heating. Anyway, there has been enough said on this thread for readers to make up their own mind. I will be signing off with this thread here, but will have several questions for SkS in the next day or so on my weblog that I will invite you to discuss on SkS.
       Response:

       [DB] "you do not understand the physics."

       Goalpost shift.  When confronted with a question (from Dikran about significance testing by you) you repeatedly and pointedly refuse to answer the question.  In this case, when pointed out that a time series of one year, in the vacuum of any significance hypotheses, is meaningless, you goalpost shift and question the knowledge of the questioner.  And again dodge the real question.

       For all readership by now are painfully aware, the real question is not whether I or they understand the physics.  The real question, whether you understand significance testing, is left patently answered by your utter refusal to properly address the question & continual efforts to change the subject.

       So unless you wish to properly answer Dikran, the answer is that you do not, that there is no significance to your short time series and the conclusions you continually impugn to them and that the time to move on has indeed come.

72099. Rob Painting at 21:11 PM on 19 October 2011
       How Increasing Carbon Dioxide Heats The Ocean
       Steve L @ 8 - Question 1: solar radiation, temperature, humidity and wind speed, all affect the rate of evaporation from the ocean surface. The giveaway is figure 2 which shows a clear relationship with longwave radiation and the cool skin layer temperature gradient. This would not likely be the case if evaporation were controlling the temperature gradient. Also, if you're saying that solar radiation (via evaporation) cools the ocean (as your post seem to suggest), then how would the oceans ever undergo long-term warming or cooling, as we know they have in the past? Perhaps I've misinterpreted your question. 2. No. It's just a description of the diurnal cycle. The important point to remember, is that lowering of the temperature gradient in the skin layer reduces heat lost by the ocean to the atmosphere, and thereby enables the ocean to steadily accumulate heat over time.
72100. Dikran Marsupial at 20:50 PM on 19 October 2011
       Continued Lower Atmosphere Warming
       Eric (skeptics) A nine year trend is so short that the difference is extremely unlikely to be statistically significant for any reasonable set of assumptions. It is Prof. Pielke's hypothesis, and so it is his responsibility to test his hypothesis rather than mine, but if he can provide a plausible set of assumptions under which there is a statistically significant difference in the trends, then that would be a perfectly reasonable answer as far as I am concerned. However, whether the difference in trends is statistically significant or not, I would like Prof. Pielke to give a direct answer to this question. This question can be answered with a "yes" or a "no", the difference either is statistically significant or it isn't, and I don't think it unreasonable to ask an eminent scientist whether his hypothesis has statistically significant support from the observations or not. If you would like to help Prof. Pielke by stating the appropriate set of assumptions and performing the test yourself, that would make a useful contribution to the discussion.

Prev  1434  1435  1436  1437  1438  1439  1440  1441  1442  1443  1444  1445  1446  1447  1448  1449  Next