Arguments
Recent Comments
Prev 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 Next
Comments 121651 to 121700:
-
CoalGeologist at 16:23 PM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Jeff Freymiller @57 Perhaps the diagram you're referring to is the one that appears in the "Response" to Post #13 on the skepticalscience.com discussion Why-is-Greenlands-ice-loss-accelerating?. The accompanying text reads, "The amount of energy that goes into ice melt is fairly small compared to the amount of energy being absorbed by the oceans. In the figure below, all the energy gone into ice melt is included in the red "Land + Atmosphere" segment" The discussion on this page provides a good background to the present discussion. -
Doug Bostrom at 15:21 PM on 1 April 2010A residential lifetime
GC, is it your claim that David Archer is recommending we take a random, unplanned and accidental stab at geoengineering? Is that what you took from his book, that Archer says we have a C02 shortage and should remedy it thereby avoiding another stade? -
gallopingcamel at 14:53 PM on 1 April 2010A residential lifetime
duog_bostrom (#2), There is no need to speculate; just cough up $23 for a copy of "The Long Thaw". -
Jeff Freymueller at 14:49 PM on 1 April 2010Greenland's ice mass loss has spread to the northwest
#51 Geo Guy, 300 gigatons per year comes from Velicogna (2009), the latest estimate from GRACE. Measured, not exaggerated. As for whether air temperature or ocean temperature is more important in the acceleration of glaciers in Greenland, that is a good question. But then why is the ocean warming up? In the end, it comes back to the radiative imbalance -- the planet is getting warmer, and some of the heat goes into the atmosphere and a lot goes into the oceans. There was a great figure on this posted here a couple of times recently, but I have been unable to find it.... -
Tom Dayton at 14:22 PM on 1 April 2010CO2 has a short residence time
Thanks again, Doug. For a long time I've been wanting somebody to write what you did. Your original post was completely clear to me; I didn't mean to imply that it was unclear or that I was being "skeptical" of it. (Funny how that formerly perfectly innocent word now sticks in my craw!) The additional thing I think would help, is a specific counterpoint to that iconic list. There are so many references in that list that I'm sure it would take rather a long time to read them all thoroughly enough. I tried a few, but I lack the knowledge to evaluate them. Maybe the time-consuming review of that list would be a good project for somebody's chemistry grad students, or even undergrads! Again, the purpose of the review would be narrow--just to state decisively what definition of residence time or lifetime they really use. So anybody reading this who has a bunch of chemistry students in need of a project, please give it a go! -
Doug Mackie at 13:58 PM on 1 April 2010A residential lifetime
Yep #4 kmcolo is right: As long as there is extra CO2 in the atmosphere then it will have an extra warming effect. Reproduced here is my reply to a question over at the i-phone ap page. The issue is the difference between residence time and lifetime. Residence time is the average time a given molecule with (if they had them) a given serial number stays in the atmosphere. CO2 is constantly undergoing exchange processes. That is, a plant takes up a molecule of CO2 and is removed from the atmosphere. At the same time an animal may be breathing out a molecule of CO2 produced by “burning” some plant matter. So long as total biomass is roughly balanced this causes no net change in atmospheric CO2. (Indeed, the sawtoothing in the Keeling curve shows what happens each Northern Hemisphere spring as the plants grow their leaves back and suck up CO2 released by their leaves rotting the previous autumn). It turns out that the average time a given molecule of CO2 spends in the atmosphere is only a few years. BUT residence time is meaningless in this concept. My bank manager does not care how much I spend so long as I have money coming in to cover outgoings. However, if INLifetime is how long before a molecule is removed permanently and not just exchanged. Some molecules are removed by undergoing change – methane is oxidised to CO2 for example. However, CO2 is (almost) chemically inert and so is only removed by an increase in total biomass or by dissolution in the oceans. The dissolution process has a bottleneck and it will be centuries before total CO2 in the atmosphere decreases. (Even then we will be in trouble as the oceans undergo acidification). See, for example the AR4 FAQ 10.3 : -
Doug Mackie at 13:49 PM on 1 April 2010CO2 has a short residence time
Thank you. Comment? Sure. Long version: The issue is the difference between residence time and lifetime.See the link above to the AR4 glossary and also the entry for lifetime in the TAR glossary . Residence time is the average time a given molecule with (if they had them) a given serial number stays in the atmosphere. CO2 is constantly undergoing exchange processes. That is, a plant takes up a molecule of CO2 and is removed from the atmosphere. At the same time an animal may be breathing out a molecule of CO2 produced by “burning” some plant matter. So long as total biomass is roughly balanced this causes no net change in atmospheric CO2. (Indeed, the sawtoothing in the Keeling curve shows what happens each Northern Hemisphere spring as the plants grow their leaves back and suck up CO2 released by their leaves rotting the previous autumn). It turns out that the average time a given molecule of CO2 spends in the atmosphere is only a few years. BUT residence time is meaningless in this concept. My bank manager does not care how much I spend so long as I have money coming in to cover outgoings. However, if INLifetime is how long before a molecule is removed permanently and not just exchanged. Some molecules are removed by undergoing change – methane is oxidised to CO2 for example. However, CO2 is (almost) chemically inert and so is only removed by an increase in total biomass or by dissolution in the oceans. The dissolution process has a bottleneck and it will be centuries before total CO2 in the atmosphere decreases. (Even then we will be in trouble as the oceans undergo acidification). See, also, the AR4 FAQ 10.3 : -
kmcolo at 13:27 PM on 1 April 2010A residential lifetime
In other words there is a difference between the lifetime of a given CO2 molecule and the lifetime of the perturbation of (increase in) the CO2 concentration. -
Pete Dunkelberg at 13:22 PM on 1 April 2010A database of peer-reviewed papers on climate change
The exact words "E&E is not a science journal" are from the editor of E&E, as google will show. Greenfyre’s blog has looked into some exaggerated claims associated with E&E. http://greenfyre.wordpress.com/2009/11/18/poptarts-450-climate-change-denier-lies/ -
Chris McGrath at 13:22 PM on 1 April 2010A residential lifetime
Here is a link to a similar post trying to explain the immense timeframes involved in anthropogenic climate change and ocean acidification based on David Archer's work: http://www.climateshifts.org/?p=750 "... the IPCC (2007) concluded that natural processes in the carbon cycle will be slow to remove the current levels of CO2 from the atmosphere. Following perturbation of the natural Carbon Cycle about 50% of an increase in atmospheric CO2 will be removed within 30 years, a further 30% will be removed within a few centuries and the remaining 20% may remain in the atmosphere for many thousands of years (IPCC 2007: 514). Archer and Brovkin (2008) reviewed long-term carbon cycle models from the recently published literature. They noted, “carbon cycle models respond to a release of new CO2 into the atmosphere in a series of several well-defined stages lasting for many millennia.” In the first stage, fossil fuel CO2 released into the atmosphere equilibrates with the ocean, which takes centuries or a millennium due to the slow overturning circulation of the ocean. Archer and Brovkin (2008: 284) noted that the lifetime of individual CO2 molecules released into the atmosphere may only be a few years because of the copious exchange of carbon with the ocean and the land surface. However, the CO2 concentration in the air remains higher than it would have been, because of the larger inventory of CO2 in the atmosphere/ocean/land carbon cycle. That is, the equilibrium processes removing fossil fuel CO2 emissions from the atmosphere operate at a system-wide level and individual CO2 molecules do not last for millennia in the atmosphere. Thus today’s fossil fuel CO2 emissions will not be “in” the atmosphere (literally) for a long period but they will continue to “affect” the atmosphere, the climate, and the oceans for many thousands of years. The equilibrium processes have a major negative side for the oceans. A consequence of the oceans acting as a “sink” for CO2 emitted from burning fossil fuels is ocean acidification, discussed in several recent posts here. Archer and Brovkin (2008: 288) point out, “after the invasion of fossil fuel CO2 into the ocean, the acidity from the CO2 provokes the dissolution of CaCO3 from the sea floor. … In the models it takes thousands of years for this imbalance to restore the pH of the ocean to a natural value.” After fossil fuel CO2 in the atmosphere equilibrates with the oceans, atmospheric CO2 will still remain about 20-25% higher than pre-industrial levels. Archer and Brovkin (2008: 287) note that, “eventually, the excess CO2 will be consumed by chemical reactions with CaCO3 and igneous rocks, but this takes thousands of years.” In an earlier publication, Archer (2005) found that the immense longevity of the tail on the lifetime of CO2 released into the atmosphere means 7% released by burning fossil fuels today will still be affecting the atmosphere in 100,000 years, and the mean lifetime of CO2 in the atmosphere is 30,000-35,000 years. He suggested an appropriate approximation of the lifetime of CO2 released by the burning of fossil fuels for public discussion is “300 years, plus 25% that lasts forever”. We commonly think of our children and grandchildren to appreciate the consequences of our present actions but as our present emissions of fossil fuel will continue to affect the atmosphere for over 100,000 years, we should appreciate the decisions on climate policies today will affect the next 5,000 generations of humanity and beyond." -
Doug Bostrom at 12:27 PM on 1 April 2010A residential lifetime
GC, Archer suggests that we're altering the climate for the long term, but can hardly be said to recommend this as a planned course of action. I wonder what he'd say about your strangely sanguine interpretation of his work? -
gallopingcamel at 12:01 PM on 1 April 2010A residential lifetime
Time constants associated with CO2 in the atmosphere are all over the map. I really like the bold speculations such as those offered by David Archer. http://geosci.uchicago.edu/~archer/reprints/archer.2005.fate_co2.pdf http://pubs.giss.nasa.gov/abstracts/2009/Schmidt_Archer.html Archer thinks big. He suggests that mankind may have the ability to postpone the next Ice Age almost indefinitely. -
GFW at 10:18 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Riccardo - the brief mention of arctic sea ice was my fault. Marginally on topic because the "health" of the sea ice is believed to influence the temperature, and hence the mass loss rate on Greenland. Geo Guy, you're throwing a heck of a lot of words up, without a lot of meaning, and a lot of it is wrong and/or based on obtuse misinterpretations of other commenters here. 300 Gt/y? Check out the (most recent) slope of the green line fit in figure 2 on this page. Yes, we're all very well aware that an ice sheet can grow in the middle while shrinking at the edges. But that graph shows the change in the total, and it's currently 300Gt/y. By the way, saying that H2O that sublimes off an ice sheet can snow back onto it is obviously a possibility. But that's not *loss*. We're talking about the 300Gt/y of net loss. My statement that the *vast* majority of any mass loss from any ice sheet, ice cap, or glacier winds up in the ocean is true. Human dam building and the amount of increase of H2O in the atmosphere are a relative drop in the bucket, so bringing up either only shows how poor your grasp of the big picture is. I never said the converse, that melting ice was responsible for all the sea level rise. Quite the contrary, right now sea level rise is *roughly* half from thermal expansion, and half from melting ice. The Boulder CO balloon measurements were indeed of the stratosphere. The stratosphere contains less than 1% of the atmosphere's H2O. I did the math for you to compare what a 1% change per year in that 1% of the atmospheric total would be in terms of sea level, and it was not noticeable. Carbon black? Ok, I meant black carbon which as that page makes clear is a component of soot. I guess reversing the word order means I don't know anything. /sarcasm My entire point in bringing up black carbon was to point out that people here know very well that there are multiple contributors to global warming and that every time you say something about "don't believe...CO2...sole cause" you're inventing a straw man. So, finally a question for Geo Guy that he should answer before any of us pay any attention to another word he posts. The question is: What is your explanation for the evolution of sea level rise over the past, say 100 to 150 years. Please compare your answer to the consensus view regarding the change in ocean heat content and change in quantity of land-ice over the same period. -
Doug Bostrom at 09:58 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy, curiously enough the title of the first article for which I provided a link-- as you did not even though you first cited it-- is "Spatial climatic variation and its control on glacier equilibrium line altitude in Taylor Valley, Antarctica." But perhaps two sets of authors with the same names independently tackled the same subject and coincidentally came up with the same title, this coincidence escaping the notice of the journal editors who thus published two papers of the same name, by authors with the same name? My point however is that using glaciers that necessarily achieve mass balance via sublimation because that is the only means they have of shedding mass as a basis for comparison of mass loss by ice sheets and glaciers with drainage readily available is misleading. More, to claim that sublimation trumps other means of mass loss is an unsupported assertion without further work. Have you calculated the potential for mass loss of the Greenland ice sheet due to sublimation? If not, you're not offering a useful counter-hypothesis to the researchers with whom you've placed yourself in contention. You either need to do that work or accept that other researchers have supported their hypotheses while you have not. To do less is not at all persuasive, no matter how many times you repeat yourself. Indeed, you seem to find your own opinions and intuitions more compelling in all cases than actual nitty-gritty research others have performed and published. That of course is your personal choice, you're free to believe whatever you want, but if you're looking to influence others you'll need to roll up your sleeves and make an effort. -
Riccardo at 09:16 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Marcel Bökstedt, here we are talking about Greenland ice sheet, not arctic sea ice. -
Tom Dayton at 09:15 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy wrote "Yes CO2 has increased but so has water vapor, and while some believe that is atrributed ot a feedback mechanism, other disagree." Geo Guy, please see my comment on the thread "Water Vapor is the Most Powerful Greenhouse Gas." If you can come up with actual citations of the "others" who you claim disagree, please post them in a comment on that thread. (Water vapor is not really on topic in this Greenland's Ice Mass thread.) -
Riccardo at 09:14 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy, my point was just clarify that no one belives that the process was just plain melting as if "people posting here do not have an understanding of glaciology". Noteworthy is the paper you quote (Stone et al.) which well describe the complexity other people and myself were trying to push, while you insisted on your point on ablation. I hope that now this oversimplification is over. -
Doug Bostrom at 08:56 AM on 1 April 2010Models are unreliable
cloneof, you'll notice that on a year-by-year basis, model output is noisy. For instance, a few years from now the Model B scenario shows a predicted dip in temperature of some two tenths of a degree, passing below your "1 degree limit", a feature we can probably agree is unlikely to be reproduced with exactitude by the actual climate. Equally, expecting Earth's annual temperature to track model output in any given year with faithful reproduction of the model output is bound to lead to disappointment. Rather than throw up my hands in sorrow over the matter, I think I'll go and try to discover why the model output graphs are not smoothed. It's a choice made by the authors, with good reason I suspect, if nothing else intended to convey that we're not to expect a monotonously predictable rise. I can well imagine the hue and cry over divergence from a smoothed result come to think of it. -
Geo Guy at 08:46 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Let me step back a bit and then focus on the mechanics of glaciers. It would appear that this post was originally wrritten to support the premise that the loss of ice in Greenland is another piece of evidence that the earth is warming due to man's activities. From my persepctive, this is an incorrect assumption and that by understanding the dynamics and mechanics involved with glaciers, we know that advances and retreats of glaciers have happened in the past, well before there was any proposed warming related to increases in atmosphereic CO2. As far as Greenland is concerned, there is a multitude of data available for people to review and publish/speak about their own theories. It would appear that some people posting here do not have an understanding of glaciology, how they are formed, what dynamics they undergo, etc - especially when it comes to assessing what is being observed in Greenland and Antarctica. There are a number of excellent papers that have been written on the subject that I recommend be read: Glacier Mass Balance and Regime: Data of Measurements and Analysis, Mark Dyurgerov, Editors: Mark Meier (INSTAAR), Richard Armstrong (NSIDC), Institute of Arctic and Alpine Research University of Colorado, Boulder, Colorado 80309 The effect of more realistic forcings and boundary conditions on the modelled geometry and sensitivity of the Greenland ice-sheet E. J. Stone, D. J. Lunt, I. C. Rutt, and E. Hanna the journal The Cryosphere (TC).Occasional Paper 55 INSTAAR/OP-55 ISSN 0069-6145 To appreciate the concept of mass balance of glaciers I suggest people visit the World Glacier Monitoring Service at http://www.geo.unizh.ch/wgms/ I also point out my previous reference by Fountain, Lewis and Doran who identifed that the main process whereby glacier lose mass in the polar regions is by sublimation and not melting. The actual article is Spatial climatic variation and its control on glacier equilibrium line altitude in Taylor Valley, Antarctica, Global and Planetary Change Volume 22, Issues 1-4, October 1999, Pages 1-10 and it is NOT the article that was linked by Doug in # 36 (had he looked at the reference he would have noted that I included the name Volume and pages of the publication it appeared in.) In response to GFW # 36, the water vopor content of the world's atmosphere as measured by ballon launches in Boulder Colorado, has increased on average 1% per year since 1980. It is obvious from that build up that the atmosphhere can accommodate more water vapor. In addition, the premise regaring the increased water vapor from sublimation of snow and ice in the polar regions, precipitates back out as snow, not water and contributes to the accumulation of snow in the upper regions of a glacier. Jeff # 37 - I am not where you got your 300 gigatons per year - according to a report entitled " Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations, originally published in Science Express on 19 October 2006, Science 24 November 2006, the rate is more like a net loss of 113 gigatons per year, obtained from the GRACE mission. I also did not say (or mean to say) that the observations have no scientific basis - it's the definitive conclusions that people make from the observations that are questionable. That position is based on the understanding that the the morpholgy and dynamics of a gacier, let alone one the size of Greenland, are too complex to make conclusions based on a few pieces of data - Jeff # 41 - I don't dispute what you posted - it is in line with normal glacial activity. The one point I will make is what we see happening to glacers today, is not related to what is happening in the atmosphere today but rather it is a result of some past event relative to that glacier. The premise of this blog is to support the contention that gloabl warming is attributable to the burning of fossil fules by man and that the many postings on the blog are meant to debunk the arguments made by people who question that theory. If I am right, then the declaration that "Greenland's ice mass loss has spread to the northwest" was made to further the argument that the earth is warming and is linked to increases in CO2 due to man's activities. My point in joining the discussion is to put forth the position that there are many other valid reasons to support alternative theories as to why Grfeenland's ice mass is in a decline. I certainly am not questioning the interpretation that the mass is on a decline. I do think however some seem to exaggerate claims (such as a loss of 300 megtons per year) and forget to factor in items such as while the fringe is losing mass, the centre of the glacier is accumulating mass. Doug # 42 - My purpose of brining up sublimation is that I do not believe (and it has been confirmed by posts here) that epople really understand the role sublimation plays in the polar regions. It is more significant than most people apparently want to give it. With regards to arctic ice disappearing, my personal view is that it is more related to warmer ocean currents (currents that have been warming since the 30's, plus incrased solar energy in the 1980's. It cannot happen due to a marginal change of 1 degree in air temperature...that was the point I was making. Ricardo # 43 - I did read that article and it is in contrast to that posed by the authors in the articles I mention above. Ned # 44 - I would dispute what you have indicated in your post. The one thing climate models have not been able to forecast (without veering off their temperature relationships) is the accommodation of the melting arctic ice cap and the observations being made in both Greenland and Antarctica. Hence your "The mainstream scientific view of climate change impacts on the mass balance of the Greenland ice sheet is a model of clarity and consistency (both internal consistency and model-observation consistency)." is not valid IMHO. Yes CO2 has increased but so has water vapor, and while some believe that is atrributed ot a feedback mechanism, other disagree. Whatever the reason, water vapor acts much more strongly towards increased CO2 and while models may interprest the results of this warming, as you have indicated, models are a close environment wheras the earth's climate is an open environment. As for polar amplification, there is conflicting views on the validity of that concept after all it was coined by Manabe and Stouffer in 1980 in their climate model's response to increasing green house gas levels. However I did read somewhere (don't have the link..sorry) where the effect of cosmic and solar radiation can be amplified at the poles - something to do with the concentration of the earth's magentic field. Your reference to physical models of glaciers isn't quite right either. Glaciers are reacting today from events that happened previously. Yes they are receeding (while some are advancing) but that is a normal characteristic of them. The current retreating of glaciers has been occurring since the 1930's (and earlier if you want to go back to the last major ice age). As for glaciers moving at an accelerated rate, that can be related to a number of factors, including calfing which is usually followed by an increase in velocity because the ice doesn't have th push that ice that fell off into the ocean. (simplistic but makes the point). In my years working in the field, one thing I have learned is in many instances things are not what they appear to be and consequently I have learned to challenege an argument by identifying alternative theories as to what is happening. That processis actually a part of the scientific process - as soon as we stop questioning the validity of an argument, we stop advancing...nuff said. With regards to Greenland, I encourage you to read the article by Mark Dyurgerov who addresses the issues with Greenland. As for the mechanism you are asking about, it has always been there. Ice melts at 0 degrees C (32F) at sea level. However, snow and ice fields are known to lose their mass at temperatures well below that figure (we are taking significant magnitudes here and not decreases related to slainity etc). That loss happens because of sublimation. I live in a place where we experience warm winter winds from time to time. We can have two feet of snow on the ground and after several days of these winds, that snow can virtually be reduced by a factor of 75% with no water run-off. As for remote sensing identifying melting - sorry it identifies the reduction in mass (gravity survey) - what we need to understand is what factors contribute to that loss in mass. That is waht I have identified in my posts - alternatives to an increase in air temperatures causing ice to melt. GFW # 45 - the water content change I cited was from regular balllon launches from Boulder CO. While the rate may not reflect the entire atmosphere - it does reflect the fact the water content during the period cited did increase (and was reported by the IPCC as to having done so). Also with repect to the increase in ocean levels, not all of it is attributable to melting glaciers. Finally carbon black isn't the same as soot so I believe you are referring to soot (carbon black is manufactured as a additive to rubber products.). Yes microspcopic pieces of carbon from incomplete burning do have a role to play in melting (soot falls on snow/ice, sun radiates energy, soot absorbs sun's energy, soot heats up, snow/ice melts. Initially it was thought that the disappearing snows on Mt. Kilamanjaro was the reult of just that process - they thought it was dust blown up from lower valleys. However after some further studies, the consensus now is the disappearing snow/ice is attributed to sublimation. -
GFW at 08:40 AM on 1 April 2010CO2 is not the only driver of climate
A great addition to this page would be a link to the page with the evolution of relative forcings over the past century or so. I just can't find that page at the moment.Response: Good idea. I may reshape the content to include the graph you're talking about but in the meantime, here it is:
Separate global climate forcings relative to their 1880 values (GISS). -
muoncounter at 07:25 AM on 1 April 2010CO2 is not a pollutant
Tom#3: These references seem to suggest those 'limiting factors' to potential sequestration are significant and supportive of your quotes under 'the bottom line'. From an older issue of Nature: "Doubts concerning the potential of natural vegetation for sustained response to rising CO2 have arisen from experiments on infertile soils, where the stimulus to growth was curtailed by mineral nutrient limitations. Here we present evidence that mineral nutrient constraints on the fertilizer effect of elevated carbon dioxide can also occur on fertile soil " Also from Nature: "Soil carbon was lost at subambient Ca, but was unchanged at elevated Ca where losses of old soil carbon offset increases in new carbon. ... differences in sensitivity of carbon storage to historical and future Ca and increased nutrient limitation suggest that the passive sequestration of carbon in soils may have been important historically, but the ability of soils to continue as sinks is limited." From Frontiers in Ecology and the Environment: "research suggests that the fertilization effect is limited by nutrients and air pollution, in addition to the well documented limitations posed by temperature and precipitation. This review suggests that existing forests are not likely to increase sequestration as atmospheric CO2 increases." -
cloneof at 07:18 AM on 1 April 2010Models are unreliable
O.k, I'm sorry if my first post sounds agressive towards a side or another, I just want this to get out of my "do-to" list. It's 2010 now and even with El Nino from what I can see from Climate4You (wich I presume is one of the most objective sources there is for climate information), no dataset reaches the 1 degree limit, like the Hansen's "B" scenario seems to have finally gone over. While indeed if I'm not incorrect and that seems to have happened, we can only hope that we have learned trough the decades (wich Hansen 2006 seems to suggest :) ) and at this day of age have had the resources and the time to create the best damn models we can[/End the dramatic b-grade speech]. -
Marcel Bökstedt at 06:55 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
The record of ice cover in the Arctic is full of rapid growths and rapid collapses. I don't think it makes much sense to discuss the trend over a month or over a year, it looks too random in the short perspective. The long term decreasing trend is clear though : look for instance at the tale of the tape from "cryosphere today". -
Doug Bostrom at 06:42 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
GFW, sheer speculation on my part but since we earlier had a powerful positive temperature anomaly over much of the Arctic ocean this winter, perhaps things were "primed" for a rapid growth of ice once air temperature slid back into a more normal regime? Easy come, easy go, maybe. For my part I'm going to reserve any judgment about the health of Arctic ice until much later, August or September. Extent is has been dethroned, seems to me, with volume being the real story now. But again, I'm speculating. -
GFW at 06:33 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
That's probably enough about Geo Guy. Does anyone have any insight into what the heck is going on with arctic sea ice extent? Is this just a short term weather phenomenon? It's pretty weird to see this kind of growth in late March. As significant as the mass loss from Greenland has been, I don't think freshwater bergs are contributing that much to sea ice. -
Jeff Freymueller at 06:11 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
#40, Geo Guy, I just noticed this in your comment: "Also glaciers move as a result of the build-up of ice in their centers which pushes the underlying ice outwards. When glaciers are retreating, you don't see that movement." This is wrong. Glaciers retreat when the melting/ablation/calving at their terminus causes more mass loss than is made up by flow. But glaciers are always flowing. If more mass flows out of a section of a glacier than is replaced by new accumulated snow->firn-ice and flow from even higher up, the glacier loses mass in that section. Some glaciers flow very slowly, but given gravity and a slope, any large mass of ice flows downhill. -
jsam at 05:18 AM on 1 April 2010A database of peer-reviewed papers on climate change
Removing a "controversial" (aka crap) journal will give succor to the sceptics. "look, they ignore us." Poor things. Maybe a separate category for those that don't pass muster?Response: I'm not removing any links. Each link is categorised. Eg - blog, peer-review study, mainstream media, etc. There are probably a few Energy & Environment articles categorised as peer-review. In order to make the database more accurate, these should be recategorised. I'll probably have to add a new category - not sure what to call it. Non-peer-review journal? Grey literature? -
Tom Dayton at 04:50 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy, it's good that you "find it difficult to accept that climate is being affected by only one factor - the rise in atmospheric CO2, (simply because there are multiple factors at play when it comes to climate)," because nobody else accepts that, either. It's a straw man. See CO2 is not the only driver of climate. -
GFW at 04:24 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
@Geo Guy, you're wrong on so many levels. Others have so thoroughly hammered on the "ice flow and berg calving" vs "melt in place" issue that I haven't felt it necessary to mention it until now. But again, that's the dominant means of mass loss from Greenland. And yes, the increase in ice flow and calving is driven by the "marginal" increase in global temperature (which is both predicted and observed to be greater at high latitudes - see "polar amplification"). I'm going to pick on something else. Your ludicrous assertion that "water content [of the entire atmosphere] has increased on average at a rate of 1% per year since 1980" Wrong. Water content of the stratosphere may have done that (see Wikipedia), but not the whole atmosphere. Such an increase in the stratosphere would deprive the ocean of ... wait for it ... less than 0.0025 mm/y. That is of course negligible compared to the 3mm/y rise we currently see, and the glacial contribution to same. There probably has been a small increase in tropospheric water vapor too, but on a similar absolute scale (not % scale). And of course that increase in tropospheric water vapor is predicted as a positive feedback in global warming. Finally, we know CO2 isn't the only factor, so fighting that position is a complete straw man argument. However CO2 is the "biggest control knob". Carbon black (aka soot) is known to be an important player in reducing ice albedo, thus contributing to the warming/melting of ice. But even if there was some way to eliminate soot emissions without changing our fossil fuel economy, that would only slow down the warming. (And indeed, there are people working very hard to reduce soot emissions.) -
Ned at 04:21 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
This discussion has gotten very strange. The mainstream scientific view of climate change impacts on the mass balance of the Greenland ice sheet is a model of clarity and consistency (both internal consistency and model-observation consistency). 1. We know CO2 and other greenhouse gases are increasing, and physical models suggest that should lead to warming overall and particularly in the northern hemisphere high latitudes (polar amplification). Observed warming from multiple sources matches this. 2. Physical models of glaciers and ice sheets suggest that this warming should lead to a negative mass balance and loss of ice via both melting (primarily in summer below the equilibrium line) and the accelerated discharge from marine terminating outlet glaciers. Remote sensing data specifically confirm (a) an increase in melting, and (b) an increase in glacier velocity. 3. Other techniques (GRACE, high-precision GPS) confirm the overall negative mass balance that would be expected from the mechanisms in (2) above. That's a very clear, coherent picture. I'm a bit mystified as to why Geo Guy would write Sometimes in science we have to step back and ask ourselves "Does it make sense?" In this case it doesn't make sense to me. Whereas to me, this topic (Greenland ice sheet) seems quite sensible and straightforward, and trying to introduce other explanations for the observed loss of mass raises more problems: What mechanism would produce a large and rapidly increasing rate of sublimation in Greenland? What evidence is there for this increase in sublimation? Why would all the remote sensing data on melting and velocity be wrong? Occam's Razor suggests that the straightforward explanation is preferable to the convoluted and mysterious one. -
Riccardo at 03:49 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy, you might be interested in digging a little deeper. Following van den Broeke et al. 2009, they calculated the overall mass balance (surfaces mass balance SMB minus discharge D) and compared it with GRACE results. The former (SMB-D) compares well with the latter (r=0.99, fig. 1 in the paper). Next they show that from somewhere in the '90s SMB has been increasingly negative and D also increased (fig. 2a). The two mechanisms turn out to be comparable in magnitude. In fig. 2b you'll find the components of SMB, namely precipitation, runoff and sublimation. Sublimation had almost no part in the balance. Also very interesting is fig.3 where they quote SMB and D separately for various regions of the ice sheet.Response: The paper van den Broeke et al 2009 is expounded upon in some detail in an earlier blog post Why is Greenland's ice loss accelerating? -
Tom Dayton at 03:35 AM on 1 April 2010CO2 has a short residence time
Excellent post, Doug! If you can find the time, will you please comment on whether the iconic list and graphic that is touted so widely on the web, contains only studies about individual molecules' lifetimes? Many skeptics throw that on the table to counter explanations such as the one you've given. -
Pete Dunkelberg at 03:25 AM on 1 April 2010A database of peer-reviewed papers on climate change
Google ""E&E is not a science journal" -
Doug Bostrom at 03:25 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
Geo Guy, perhaps I'm misunderstanding you, or maybe you need to add just a jot of qualification to your writing. When you say "...my point is the ice loss identified by GRACE is not due to melting. There are other factors at work there - similarly to what is going on in the arctic. " I take it you do not discount the loss of ice mass, but you are pointing out that no single process is accountable for all of the loss of mass, the movement of water in space and state? I'm sure you're right about that. Of course, nobody here or elsewhere (well, the sane, anyway) has said that every last gram of ice seen to vanish in the past few decades is down to a single factor, so you won't find anybody worthwhile to argue that point with you. What we can say (and I imagine you could model this if you cared to take the time) is that sublimation alone cannot account for the entire loss of mass on the Greenland ice sheet. As to your speculation about the available amount of extra energy required to produce a phase change of a given mass of water from solid to liquid (melt ice), as an exercise take a look at the summer Arctic sea ice anomaly for any of the past few years and then compute for yourself the additional energy being absorbed by the ocean due to the loss of albedo. In case you don't want to do that work, I'll cut to the denouement, plot spoil and say that where energy arrives counts for a lot; using global temperature change to predict the behavior of ice in a given region is a futile approach. -
Jeff Freymueller at 02:55 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
#40 Geo Guy, the mechanism for much of or most of the ice loss is glaciers flowing and dumping ice into the ocean. John said this in the original post. The ice does not have to melt in place. If the lower part of a glacier accelerates due to, for example, its interactions with warmer water at its terminus, or increased lubrication due to melting on its lower part, accelerated ice flow will propagate up glacier and into the ice fields/ice sheet that feed the glacier. The ice thickness changes as a result of this flow, and these changes have been observed directly in addition to the indirect observation of Khan et al. (the earth is responding like a scale to the ice, and the GPS is measuring the upward displacement of the scale as the weight on it is removed). This is not my idea -- it is based on direct observations (visual, time-lapse photos), glacier velocity observations, basic glacier physics, and even seismic recordings. And nobody here is saying that the ice loss is all due to melting in place, except perhaps those who suggest they don't believe any of this because the ice can't be melting in place. -
Jesús Rosino at 02:20 AM on 1 April 2010A database of peer-reviewed papers on climate change
These are the ones I've seen: 'It hasn't warmed since 1998' Limits on CO2 Climate Forcing from Recent Temperature Data of Earth 'Oceans are cooling' Cooling of the global ocean since 2003 'Hockey stick is broken' A 2000-year global temperature reconstruction based on non-treering proxies 'Climate's changed before' A 2000-year global temperature reconstruction based on non-treering proxies -
Geo Guy at 02:04 AM on 1 April 2010Greenland's ice mass loss has spread to the northwest
# 37 - Jeff Its not the observations that are wrong, its the interpretation to those observations that are off base. With regards to sublimation, if that is not the driving force for ice loss in sub zero weather, perhaps you can tell us what is. Please don't say a 1 degree increase in atmospheric temperatures brought on by man made CO2 - that just does not make any sense. Even if the temperatures went from minus 20 to minus 10, that still will not result in melting of polar glaciers etc. With regards to GFW - your view assumes a constant level of water vapor in the atmosphere but in face the water content has increased on average at a rate of 1% per year since 1980 - hence the water resulting from the sublimation of ice fields does not all end up in the ocean. Everyone seems to assume when glaciers reduce in size it is because they are melting. What I am trying to point out is that in the polar regions and higher elevations, a small increase in average global temperatures will not and cannot melt those glaciers by itself. Something else is at work and we need to look at the other driving forces that affect glaciers to determine just that. Also the disappearance of glaciers at their margins is a normal observation - they disappear in the areas of ablation. Also glaciers move as a result of the build-up of ice in their centers which pushes the underlying ice outwards. When glaciers are retreating, you don't see that movement. Simply posting maps here showing larger areas of ice loss over a given period of time is meaningless. It certainly is no way near being "Quad Erata Demonstratum". As for Doug, # 34, my point is the ice loss identified by GRACE is not due to melting. There are other factors at work there - similarly to what is going on in the arctic. Those observations reported do NOT support the theory that man-made CO2 is causing warmer temperatures that are resulting in the disappearance of the Greenland ice. Also the glaciers in South America and in Africa that have disappeared are not closed systems and their disappearance has been attributed to sublimation and not warmer temperatures. As I mentioned in a previous post, the thermodynamics required to melt that ice simply from a rise in temperature just are not there. For instance, the energy needed to melt a volume of ice is the same temperature needed to raise the temperature of the resulting water to a 140 F level. With a global temp average increase of under 1 degree over 100 years, you do not need a science degree to figure out that polar ice is not disappearing from that marginal increase in temperature. One last word on the subject, the IPCC identified in one of its reports that glacial melting has been noticeable since 1970. In fact, geological literature identified glacier melting in the 1930's - well before the recorded increase in CO2 levels as measured in Mauna Loa. In addition, the rising temperatures in the arctic oceans were identified in the 1930's so what were are seeing today started well before 1970. Just as I find it difficult to accept that climate is being affected by only one factor - the rise in atmospheric CO2, (simply because there are multiple factors at play when it comes to climate), I also find it difficult to accept that the polar ice cap and glaciers are reducing simply due to one factor when there are so many others at play. Sometimes in science we have to step back and ask ourselves "Does it make sense?" In this case it doesn't make sense to me. -
mspelto at 23:25 PM on 31 March 2010Greenland's ice mass loss has spread to the northwest
2009 melt anomaly in Greenland was not that large. For the Bulletin American Meteorological Society 2009 State of the Climate (in press), I write the Glacier and Ice Sheets section. Here is the line on the melt anomaly..."On the Greenland ice sheet SSM/I brightness temperature daily variations (Tedesco, 2008) identifies melt extent and number of melting days compared to the 1979-2008 average. Negative anomalies occurred in 2009 along Southern and West Greenland, positive anomalies along Northern and East Greenland. The melt extent was 670, 000 km2, slightly lower than in 2008. Surveys of Greenland marine terminating outlet glaciers from MODIS imagery (J.Box, Ohio State U. Byrd Polar Research Center) indicate that the 34 widest glaciers collectively lost 106.4 km2 of ice between late summer 2008 and late summer 2009. " So melt anomalies were above normal in the northern section of the ice sheet, but not a record. -
Jesús Rosino at 23:24 PM on 31 March 2010A database of peer-reviewed papers on climate change
John, inline comment in #6: "[E&E] no, it's not a peer-reviewed journal" Then, shouldn't they be removed from the peer reviewed papers list? I also agree that E&E shouldn't be considered peer-reviewed, because it is not a scientific journal, but a social science journal. It is not carried in the ISI listing of peer-reviewed journals. Its peer reviewed process has been widely critizised for allowing the publication of substandard papers. The editor has said “I’m following my political agenda — a bit, anyway. But isn’t that the right of the editor?”. See also this article published in Environmental Science and Tecnology (a journal of the American Chemical Society), and has recently made it clear that she is interested in the conclusions of the papers rahter than the methodology.Response: Fair call, it's probable that E&E papers are currently categorised as peer-review in my database. Feel free if you find any such papers to let me know which skeptic argument they're listed under and I'll recategorise them. -
Ned at 23:17 PM on 31 March 2010The 5 characteristics of scientific denialism
And yet another entry in the do-it-yourself surface temperature programs! New ones seem to be popping up about one per week. Once again, the results closely match those from GISS, CRU, NCDC, and the other "amateur" analyses linked above. Here's a comparison of eight different versions:
Not shown in that graph are results from Tamino (who's temporarily offline while moving) and Clear Climate Code (whose results are identical to GISSTEMP).
What does this comparison show?
(1) The increasing global mean surface temperature trend is not caused by "manipulation" of the data by NASA or UEA-CRU.
(2) The increasing global mean surface temperature trend is not an artifact of particular algorithms or methods (multiple studies using the same input data but different methods get the same results).
(3) Several of these people have now done comparisons of stations that were dropped in the 1990s vs those that were not dropped, and have found no significant difference in the trends. (I.e., Watts and D'Aleo are clearly wrong.)
(4) "Amateurs" (no insult intended; these people are highly skilled ... but climate science is an avocation rather than vocation for them) can make a very substantial contribution to the field. IMHO this is pretty neat.
-
Dennis at 23:16 PM on 31 March 2010A database of peer-reviewed papers on climate change
Re: Energy & Environment -- Given the competing claims that Energy & Environment is/is not peer reviewed, this is a good time for any climate scientists (or, for that matter, any other scientists) who have peer reviewed papers published in Energy & Environment to step forward and identify yourselves. You don't have to identify the paper, only that you have peer reviewed for E&E. -
Berényi Péter at 22:35 PM on 31 March 2010Greenland's ice mass loss has spread to the northwest
For a historical perspective: Was there a 1930s Meltdown of Greenland Glaciers? by Adam Herrington True, it is an undergraduate rersearch paper at the Ohio State University, still, it says something. It also provides plenty of literature on the subject. -
Ari Jokimäki at 21:51 PM on 31 March 2010A database of peer-reviewed papers on climate change
Energy & Environment is not generally considered as peer reviewed even though they claim to be one. They seem to be only publishing papers that go against the mainstream climate science, and the papers also seem to be of questionable quality. -
Mikko at 21:25 PM on 31 March 2010A database of peer-reviewed papers on climate change
http://en.wikipedia.org/wiki/Energy_&_Environment Many of the "sceptical papers" have been published in the Energy & Environment. Is it Peer-Reviewed, Academic Journal as EBSCO lists it? Or is it a trade journal as Scopus lists it? Which is more reliable EBSCO or Scopus list?Response: My understanding is all articles published in Energy and Environment were reviewed by the editor Sonja Boehmer-Christiansen. In other words, no, it's not a peer-reviewed journal. -
Ari Jokimäki at 20:44 PM on 31 March 2010A database of peer-reviewed papers on climate change
Thanks for the traffic, John! :) -
Jesús Rosino at 19:16 PM on 31 March 2010A database of peer-reviewed papers on climate change
Ari's AGW Observer has a useful index page listing all the paperlists: http://agwobserver.wordpress.com/index/ -
Mikko at 19:14 PM on 31 March 2010A database of peer-reviewed papers on climate change
http://www.populartechnology.net/2009/10/peer-reviewed-papers-supporting.html Hi experts. Pleas comment this link. I have feeling that it is another hoax of the denialits. -
RSVP at 18:32 PM on 31 March 2010The human fingerprint in global warming
In tracking global atmospheric composition, the implications of change goes beyond effects on Earth's temperature. In fact, climate may be the least significant issue. For instance, life (as we know it) cannot be sustained without oxygen. Mathematical projections on global ice melting, temperatures, sea level rise, etc., are commonplace on this site, yet general questions on bio-sustainability are typically avoided. And while these issue may hold a higher priority for limiting fossil fuel burning, the focus here attemps to limit itself to safeguarding the climate theory behind AGW (i.e., the relationship between CO2 levels and global warming). And with all the data and resources currently dedicated to this issue, it would seem proper to apply it to a higher purpose. Not only would there be more interest and motivation, there is a higher chance of actually acheiving goals relative to the reduction of GHG emissions. -
Jeff Freymueller at 16:32 PM on 31 March 2010Greenland's ice mass loss has spread to the northwest
#33 Geo Guy, yes, but 300 gigatons per year by sublimation due to changes in winds? Please. Not credible. You are going to have to do better than a blanket claim that all of the observations being made about Greenland have no scientific basis. On what basis do you make that sweeping claim? -
GFW at 16:26 PM on 31 March 2010Greenland's ice mass loss has spread to the northwest
And even beyond that, let's consider an imaginary ice sheet somewhere undergoing significant annual mass loss via sublimation. Um, where does the ice go? Into the air as water vapor. And then? It rains out ... and winds up in the ocean. Simple fact - any loss from any ice sheet winds up in the ocean. Yes, humans have created some extra lakes with dams, and a warming atmosphere will almost certainly retain more water vapor, but the former is a relatively small (though measured!) effect while the latter is obviously something that an AGW denier isn't going to want to talk about.
Prev 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 Next
