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Doug Bostrom at 04:50 AM on 2 April 2010Tree-rings diverge from temperature after 1960
Malcolm, the research you wish for is very much in play. Simply bounce over to Google Scholar, try searching on "plant metabolism anthropogenic C02" or "plant metabolism acid rain" and you'll see what I mean. The first term produces some 7,000 results, the second (being the subject of earlier interest) over 45,000. Plugging in better terminology for search terms will yield more and better results. -
Riccardo at 04:32 AM on 2 April 2010Tree-rings diverge from temperature after 1960
MalcolmMcDonald, "surely we need to know what's going on?" i agree but it's not up to climate scientists. I'd be tempted to ask for more research funds, but you know, people would think it's just the standard complaint from scientists. -
MalcolmMcDonald at 03:59 AM on 2 April 2010Tree-rings diverge from temperature after 1960
I don't think this is good enough. The "divergence" is evidence, surely, of some severe environmental stress, one that could at any moment start to impact on our food supplies. If this was any other branch of regular science, an expermiment would be rigged up, 6 or 16 greenhouses in a row, one with increased CO2, one with reduced CO2, one with artificial acid rain, one with extra ultra-violet and so on and so forth. We'd have at least parts of the answer in 12 months. Why is nobody treating this problem as a matter of urgency, surely we need to know what's going on? -
FerdiEgb at 03:12 AM on 2 April 2010The human fingerprint in global warming
Tarcisio José D'Avila at 05:14 AM on 30 March, 2010 I question the assertion that the relationship c13/c12 may indicate that the increase of CO2 in atmosphere is the result of burning fossil energy. The absorption of CO2 by oceans and plants tend to dominate the CO2 released by decomposition of organic matter (CO2 cold). CO2 of all sources is quite rapidely mixed within a few days to a few months within each hemisphere. The passing of the ITCZ (at the tropics) from the NH to the SH takes some more time, currently some 14 months to reach the South Pole. The 13C/12C ratio is a good indication of the source: besides fresh organics and fossil organics, all other sources of carbon have a higher 13C/12C (d13C) ratio. That are volcanic eruptions, carbonate rock wearing and (deep) ocean degassing. But how can we make a differentiation between fresh organics and fossil one's? There are two ways: fresh organics have some 14C built in from cosmic rays or nuclear tests. That is used for carbon dating, up to some 60,000 years. Fossil carbon is completely depleted of 14C. The decline of 14C in the atmosphere was observed around 1870 and carbon dating had to be corrected. The second method is from the oxygen balance: We know how much fossil fuels were sold (taxes!) and how much oxygen that needs. The oxygen use since about 1990 was measured and there is somewhat less used than calculated. That means that the whole organic world acts as an oxygen source, thus a (preferentially 12C) CO2 sink (photosynthesis...). Thus the decrease in d13C is from fossil fuel burning and nothing else. -
FerdiEgb at 02:52 AM on 2 April 2010The human fingerprint in global warming
Arkadiusz Semczyszak: The ice core with the highest resolution (8 years for 2 out of 3 ice cores of Law Dome) and a spread of only 1.3 ppmv (1 sigma). These have an overlap of about 20 years (1960-1980) with the atmospheric data taken at the South Pole. There is practically no CO2 gradient at the South Pole. Moreover, ice cores with completely different temperature profile and accumulation speed all show the same CO2 levels for the same gas age within a few ppmv. Ice core CO2 start to increase and d13C to decrease around 1850. That is at the same moment that this happens (at a different level) in the upper oceans as has been measured in coralline sponges. Stomata (index) data show the same increase in CO2 for the past century (they are calibrated... against ice cores!), but rather unreliable indicators for past changes, as they react on local/regional CO2 levels over land, which are heavily influenced by land changes over time... -
michael sweet at 02:38 AM on 2 April 2010A residential lifetime
In the post at RC, Matthews and Weaver appear to have not considered that if CO2 emmision is stopped, aerosol emmisions will also stop. The aerosol emmsiions currently cool the globe (amount uncertain) so temperatures would immediately rise. It looks like their model needs some more work, although it is an interesting way to look at the problem. -
FerdiEgb at 02:20 AM on 2 April 2010A residential lifetime
Tom Dayton, Thanks for the link... It seems somewhat overdone at RC: Around 2000 there still was some heat "in the pipeline" from the oceans. But that completely disappeared in a few years time. Thus if we should stop our CO2 emissions today, in a period of about 40 years the extra CO2 (some 100 ppmv today) would be halved, including the forcing (+ feedbacks) related to that amount of extra CO2. Thus cooling the atmosphere down as can be seen in the graph for the Bern model, or maybe faster, as the Bern model is rather conservative. -
johnd at 02:11 AM on 2 April 2010A residential lifetime
If the rate of ocean transfer of CO2 is controlled by the slow circulation and turn over, taking roughly 500-1000 or so years, then surely the heat transfer will be subject to the same slow circulation and turn over. -
Ned at 01:27 AM on 2 April 2010A residential lifetime
Normally I wouldn't try to speak for David Archer, but having read quite a bit of his work (including The Long Thaw -- I concur with your recommendation of it, BTW) my guess is he'd probably say that: (a) Our distant descendants in AD 52010 would probably be able to prevent the onset of the next glacial advance if necessary without any help from us, and (b) In the meantime there's much more danger from warming (which is actually happening) than from cooling (which isn't). I'm all in favor of prudent concern for the future, but I think we should probably focus on the next couple of centuries rather than some hypothetical condition tens of thousands of years in the future. -
Ned at 01:18 AM on 2 April 2010A database of peer-reviewed papers on climate change
Poptech, sorry I missed your post. Don't take the moderation personally. Like Doug, I've had a number of my own comments excised. I take it as a reminder to be polite and not to accuse others of lying or dishonesty. Sometimes the bad habits I pick up at other blogs can be hard to shake. Back on topic ... John, thanks for setting up this database. Is there any particular way you'd like to have the titles handled? I noticed several people had been using the article title, followed by author's name and year in parentheses (e.g., Interactive investigation of climate science topics via a collaborative web portal (Cook et al. 2010)). That seemed like a good idea to me, so I adopted it....Response: I've done either but lately I've been adding the (Cook 2010) at the end just to add some useful info - it's handy to see at a glance who wrote it and when it was written.
That web portal paper sounds like a cracker :-) -
gallopingcamel at 01:18 AM on 2 April 2010A residential lifetime
quokka (#12), Great video! I thought it was excellent. John Cook is right about Richard Alley's "American Idol" appeal; he will not be able to give up his day job as Harvard's Tom Lehrer was able to do. -
gallopingcamel at 01:15 AM on 2 April 2010A residential lifetime
doug_bostrom (#7), Thus far I have not offered my opinion as I see no point in annoying the thoughtful people who hang out here. David Archer has some very interesting speculations with huge implications if true. Archer is trying to model the effects of large CO2 emissions (up to 5,000 Gtonne C) over 500,000 years. He suggests that high emissions could delay the onset of the next Ice Age: http://geosci.uchicago.edu/~archer/reprints/archer.2005.trigger.pdf -
Alexandre at 01:04 AM on 2 April 2010A residential lifetime
Doug, Thanks for the guest post. I read the oceanic uptake can only remove part of the extra atmospheric carbon, and the rest would have to rely on the geological response of rock weathering, stretching the process to hundreds of thousands years. Do you agree? -
Tom Dayton at 00:43 AM on 2 April 2010A residential lifetime
FerdiEgb wrote "Thus it seems that the CO2 sink in the deep ocean will continue for a long period, removing most of the extra CO2 in relative short time (half lifetime around 40 years), for 99% of the current amounts, the moment we stop all emissions." There is a study also described in the RealClimate post Climate Change Commitments, projecting the rate of global temperature change if humans suddenly stopped all our CO2 emissions. -
Ned at 23:04 PM on 1 April 2010A residential lifetime
HenryH writes: More CO2 and CH4 -> higher temperatures. Higher temperatures -> more extra CO2 and CH4 by releases from the ocean and the land and its flora and fauna. What is the goal of this escalating effect? Why does it happen never in the last several billion years? Not sure what you mean by "goal" but this happens all the time, and not just with CO2 and CH4 but with other feedbacks. Some initial forcing causes the climate to change (comet impact at Chicxulub, change in solar irradiance, anthropogenic emissions of CO2, large-scale emissions of CO2 from flood basalt episodes, ...) This warming (or cooling) is then amplified by various positive feedbacks involving further increases (or decreases) in CO2 and CH4 as you note, as well as water vapor, albedo, etc. There are also negative feedbacks that reduce this amplification. The glacial/interglacial cycle is a good example of this. The initial Milankovich forcing is enough to get the process started, but the full magnitude of the swing in temperatures would not occur without the positive feeddbacks. -
Ned at 22:53 PM on 1 April 2010A residential lifetime
HenryH writes: The glacial periods are driven by the distance between the sun and the earth, not by the CO2! First of all, it's not "the distance between the sun and the earth," it's the eccentricity of the earth's orbit, obliquity of its axis of rotation, and precession. More to the point, there have been plenty of other cases where changes in temperature were driven by changes in CO2. See, for example, this comment and the rest of that thread. There are lots of examples of CO2 causing warming (or decreases in CO2 causing cooling). The fact that some fires are caused by lightning does not mean that other fires are not caused by arson. The current warming is obviously caused by greenhouse gases, not by Milankovich cycles, which don't operate on decadal to century timescales..... -
thefrogstar at 22:33 PM on 1 April 2010A residential lifetime
If the word "flux" was more widely used (or understood) then it might help put across these points. That, and the difference between "equilibrium" and "steady state". (As the old joke goes: "Old chemists never die, they just reach equilibrium") -
HenryH at 22:14 PM on 1 April 2010A residential lifetime
Yes, indeed, weathering is removing CO2 from the atmosphere... But this process cannot explain the rapid up and down in the CO2 concentration in the atmosphere. The glacial periods are driven by the distance between the sun and the earth, not by the CO2! -
FerdiEgb at 22:11 PM on 1 April 2010A residential lifetime
Seems that it is very difficult to explain the difference between residence time and excess lifetime. The first is governed by the exchange rate over the seasons, which is about 20% of all CO2 in the atmosphere, leading to an average residence time of a CO2 molecule (whatever the source) slightly of over 5 years. The second is governed by the sink rate, which is only 0.5% of any extra amount of CO2 in the atmosphere (whatever the source), slightly under halve of human emissions (land use changes not included). This sink rate remained remarkably constant in the past 110 years: 55% of the emissions (as quantity, not as individual molecules) remained in the atmosphere, 45% were absorbed by oceans and vegetation. That the sink rate remained constant was recently confirmed, which means that the oceans still are not saturating. The very long tail need some criticism: only when enormous quantities of oil and coal are burned (3000-5000 GtC according to Archer, we are now at a total 320 GtC), the deep oceans will increase substantially in CO2/carbonate content which only slowly will decay. With the current total of emissions, the deep oceans only increased in DIC (dissolved inorganic carbon) with less than 1%. Thus only less than 1% of the current total of emissions would stay in the atmosphere for an extremely long period. Further, the deep oceans are a quite good sink. The main sink of the oceans is in the NE Atlantic, where the THC moves cold water rich(er) in CO2 directly into the deep. That may come back in over a thousand years (mixed with the rest of the deep ocean) in the tropical Pacific. The surface/deep ocean exchanges are about 100 GtC/year, but based on the isotopic dilution of the fossil d13C fingerprint, some 60 GtC is directly or indirectly exchanged between the atmosphere and the deep oceans, including most of the 4 GtC sink rate. Thus it seems that the CO2 sink in the deep ocean will continue for a long period, removing most of the extra CO2 in relative short time (half lifetime around 40 years), for 99% of the current amounts, the moment we stop all emissions. -
CBDunkerson at 21:57 PM on 1 April 2010A residential lifetime
RSVP, the relationship between global temperatures and the amount of time that CO2 levels remain high is somewhat complicated. In general, cold water is a much better CO2 sink than warm water. This can be seen in maps showing net change in ocean pH from acidification... the greatest change is found near the poles where the water is colder and absorbs more CO2. Indeed, if the oceans got warm enough they could eventually reach the point where they were releasing more CO2 than they were sequestering. However, warmer temperatures and higher CO2 concentrations also mean more plant life up to a point... and while most of that plant life just briefly stores CO2 before dying and releasing it again, some percentage finds its way to the bottom of the oceans and is locked away there by cold deep sea temperatures. In a further complication, the 'snowball Earth' scenario shows that cold isn't an absolute benefit for sequestering CO2 because if it gets cold enough the oceans freeze over... and ice doesn't absorb CO2. This happened around 700 million years ago. The Earth nearly froze solid, but because there was so much ice all the CO2 going into the atmosphere from volcanic sources STAYED there and eventually built up enough to warm the planet. Setting aside the extremes and taking the balance of forces we'll see diminishing returns on carbon sequestration as the temperature increases. The most recent studies show conflicting results on whether this 'saturation' and accelerated atmospheric accumulation has begun. Not that it really matters on any practical timescale. One need only look at the ice core records to see that every time CO2 levels have risen ~100 ppm (usually taking a couple thousand years, but only about 150 in the current case) it has then taken around 100,000 years to slowly descend back down to that previous level. So, unless we have some way of vastly increasing the speed of carbon sequestration, comparable to the vast increase in its release we have introduced through burning fossil fuels, we've got a clear record that natural processes will require 100,000+ years to reverse the increase we have NOW (~390 ppm from 278 before the industrial revolution) and much longer as we continue to use fossil fuels going forward. -
quokka at 21:09 PM on 1 April 2010A residential lifetime
On a lighter note, it seems that Richard Alley is something of a musician. Geoman: http://www.youtube.com/watch?v=7-yJyM2s6ow&feature=relatedResponse: That has to be one of the nerdiest songs I've ever seen. Gotta love Richard Alley, what a character. -
CoalGeologist at 18:07 PM on 1 April 2010Greenland's ice mass loss has spread to the northwest
The current dialog on climate change involves more than just a compilation and interpretation of scientific evidence. We are confronted with diametrically opposed viewpoints on nearly every line of evidence, centered specifically on the question of human attribution. Thus, an equally important issue--and doubtless MORE important in many discussions--is whom to trust as authorities. SkepticalScience.com has placed a priority on evidence reported the peer-reviewed scientific literature, without reference to politics, accusations of deception, or inferences of nefarious goals of climate researchers. From this standpoint, the reference to "Alarmists" in the original Post (#20) by GeoGuy might have been regarded as inconsistent with the Comments POlicy, as the term means "One who causes others to become alarmed without cause". In other words, it implies an intent to cause fear, but without a valid reason. Fortunately, the subsequent discussion has focused exclusively on whether various skeptical arguments can be supported or refuted, based upon evidence in the scientific literature. The term "alarmist" has not appeared again (until now :-( !! ) Bravo to GeoGuy and all respondants to a civil dialog that has been both interesting and informative. The purpose of my present post is to note that we have more to learn from this discussion than arcane details about the rates and underlying causes of loss of ice mass in Greenland, including: 1) Implying an underlying "motive" to those who merely report or discuss research findings is not helpful, assuming the goal is to gain an unbiased understanding of what these findings show, and 2) Asking skeptical questions is not only not wrong, it's the right thing to do in scientific inquiry, assuming that the skeptical hypothesis(es) is testable and refutable by well-documented, verifiable evidence. Anyone who questions the willingness of this site to actively entertain skeptical arguments would do well to read back through the posts and replies. -
Ian Love at 17:57 PM on 1 April 2010A residential lifetime
re HenryH: "Why should it happen today in another way like in former times?" It is quite simple - we humans are pushing extra CO2 out with the result that the natural balance is upset, and heat is rapidly being absorbed by Earth. The evidence is in the rapid growth of atmospheric CO2 level. Our time scale is tens of years, the natural one is millenia or even millions. -
RSVP at 17:54 PM on 1 April 2010A residential lifetime
Is residence time affected by temperature? And if so, what is the nature of this feedback? -
HenryH at 17:48 PM on 1 April 2010A residential lifetime
More CO2 and CH4 -> higher temperatures. Higher temperatures -> more extra CO2 and CH4 by releases from the ocean and the land and its flora and fauna. What is the goal of this escalating effect? Why does it happen never in the last several billion years? Is the climate a ball on a knife edge? The last 65 million years demonstrates that the temperature was explicitly forced by the continental drifts, by the distance between the sun and the earth and by the solar activity. All that time the CO2 and CH4 concentrations in the atmosphere was following the temperature situation. To argue the converse is definitely impossible! Why should it happen today in another way like in former times?Response: This is a good question and I strongly recommend viewing the lecture The Biggest Control Knob: Carbon Dioxide in Earth's Climate History by geologist Richard Alley for an excellent overview of the whole issue. Carbon dioxide is removed from the atmosphere by rock weathering. As the earth warms, rock weathering activity removes CO2 from the atmosphere at a faster rate. This acts like a natural thermostat stopping the Earth from getting too hot.
Conversely, when it gets colder, rock weathering slows both due to lower temperatures and ice sheets covering continental surfaces. This leads to a rise in atmospheric CO2 levels which warms the Earth. Again, CO2 acting like a natural thermostat stopping the Earth from getting too cold.
However, rock weathering will not save us from human CO2 emissions now. It's a very slow process - the amount of CO2 removed is several orders of magnitude smaller than the amount of CO2 we're emitting into the atmosphere. -
Ebel at 17:22 PM on 1 April 2010A residential lifetime
The mixing of individual destiny with all is not only for CO2 a popular argument of denier. There would be a saturation of the greenhouse effect: photons from the surface do not reach the space. But there, where the atmosphere absorbs strongly, it also emits strongly. That's photons from the surface not reach the space, but others - who cares? Unfortunately, the climate-scientists support that with transparency curves. -
Doug Bostrom at 17:05 PM on 1 April 2010A database of peer-reviewed papers on climate change
Poptech, you should read and comprehend the Comments Policy. John Cook is determined to keep a civil tone on this site. As opposed to being a rejectionist I myself am an "alarmist" and found it took me a fair while to be recalibrated from veering, wild hysteresis I'd developed hanging around other climate sites. Several of my posts were permanently interred before I caught on. -
Jeff Freymueller at 16:42 PM on 1 April 2010Greenland's ice mass loss has spread to the northwest
#58 CoalGeologist, yes that is exactly the figure I was thinking about. Thanks! -
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].
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