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Comments 121551 to 121600:

121551. Tom Dayton at 14:59 PM on 4 April 2010
        A residential lifetime
        gallopingcamel and johnd, I believe your comments on plants belong not on this thread, but on "CO2 is not a pollutant".
121552. Tom Dayton at 14:55 PM on 4 April 2010
        A residential lifetime
        johnd, how about taking that topic over to "It’s land use"?
121553. johnd at 14:53 PM on 4 April 2010
        A residential lifetime
        gallopingcamel @66. Similar FACE experiments growing wheat in Victoria resulted in improved growth and yields with improved utilisation of moisture but protein % were slightly down due to nitrogen limitations. I'm not sure whether the increased yield, + 17%, meant that each plant still maintained the same nitrogen uptake . From what I recall the total protein yield of each plant was the same or even more but did not match the increase in wheat yield. It is a natural fact of cropping that often protein % rises when wheat yields fall and vice versa.
121554. Tom Dayton at 14:52 PM on 4 April 2010
        A database of peer-reviewed papers on climate change
        Harold, for responses to McKitrick's claims about warming and economic activity, see It’s land use.
121555. johnd at 14:41 PM on 4 April 2010
        A residential lifetime
        Doug Mackie @64. I'm not trying to take this off topic, is there a more appropriate thread for this line of thought? However to respond to your comments, it is the relative effect of 10 Gt of concrete added to the earths surface as infrastructure globally each year against the 3.3 Gt of CO2 added to the atmosphere each year that I was hoping to have quantified.
121556. gallopingcamel at 14:35 PM on 4 April 2010
        A residential lifetime
        Philippe Chantreau (#60), You really need to be more aware of recent history. Just to get you started, I recommend the following video by the "History Channel". It does not take sides in the Alarmist/Denier debate but it explains climate change over the last 1,000 years in an interesting way. Enjoy: http://www.veoh.com/browse/videos/category/educational/watch/v158890018kQaxQaK Getting back to the residence time of CO2 in the atmosphere, do you see this as something that mankind can influence or would you leave it up to nature? The FACE experiment (NASA/Duke university) showed that the rate of sequestration by trees is affected by CO2 concentrations. If such effects are significant the relevant time constants could be much shorter than those suggested at the top of this thread. On another thread, Tom Dayton has pointed out that the growth spurt in loblolly pines caused by elevated concentrations of CO2 tends to be short lived owing to limitations in other nutrients such as nitrogen. However, it is likely that higher CO2 concentrations will favour plants that can acquire nitrogen directly from the atmosphere (e.g legumes), especially if agricultural incentives are in place. Imagine "Bean Mountains" as well as wheat and rice mountains. Throw in Olive oil lakes and maybe we can cook up something tasty and nutritious when the next Tambora blows its top.
121557. johnd at 14:23 PM on 4 April 2010
        Temp record is unreliable
        Riccardo, Spencer wasn't presenting his analysis as complete, but believed what differences he found are sufficient to justify a more complete independent analysis. Given that there are few stations where one can be confident of the data being not being biased by the UHI effect perhaps it does warrant careful analysis. Aren't satellite based temperature measurement equipment calibrated against "known" conventional temperature measurements? If not what are they calibrated against? The accuracy of satellite measurements despite the sophisticated instrumentation, will only be as accurate as the standard used to calibrate them.
121558. Tom Dayton at 14:19 PM on 4 April 2010
        A database of peer-reviewed papers on climate change
        Harold, I've published in peer-reviewed journals and peer-reviewed conference proceedings, submitted grant proposals to peer-reviewed granting agencies, and been a reviewer for all those and a reviewer of book proposals to publishers. I've also had submissions rejected by all those. All that has not been in climatology, but in the multiple fields experimental cognitive psychology, research methodology, decision theory, and human-computer interaction. From what I can tell by looking completely from the outside at climatology's peer review process, it seems to be working just fine, and quite similarly to peer review in the my fields that I listed above. Are there problems? Sure. Is there room for improvement? Sure. I've never been happy about being rejected. Sometimes I've been furious. Sometimes I've known that my submission was rejected despite worse work being accepted. I've reworked submissions multiple times, despite disagreeing that rework was needed, to suit the demands of reviewers and editors. I've got some rejected submissions sitting around that I've effectively given up on, though I probably could get them published if I added some experiments to them (but now I've got more interesting things to work on). But I've never publicly posted a screed about a rejection. I'm flabbergasted that McKitrick has done so. McKitrick's experience was typical for anyone whose submitted work is severely and fundamentally flawed. Reviewers are not necessarily going to spend the time to list, nor even look closely enough to notice, all the problems with a submission if right off the bat they discover a fatal flaw. Reviewers and editors will advise the author sufficiently so the author can rewrite the paper, if the reviewers and editor think the paper is fundamentally sound enough to be a useful addition to the literature. But otherwise they will not spend the time to help. They will name just the first fundamentally fatal flaw and reject the paper without inviting resubmission. If the author fixes that flaw and resubmits, then the reviewers will read on to discover more flaws. It's the author's responsibility to ensure their submission is high enough quality to be accepted. McKitrick's submission was not. All the things he complains about in his public screed have been publicly addressed, and his paper is just... well, wrong.
121559. Doug Mackie at 10:52 AM on 4 April 2010
        A residential lifetime
        John Russel @55 Yes, reforestation can be a help. BUT ask this question: How much of the current “extra” CO2 in the atmosphere is due to deforestation and/or soil degradation and how much is due to fossil fuel burning? The answer is that reforestation and reforming soils will help but it will never be a significant contribution to reducing atmospheric CO2 UNLESS we have some way of reforming fossil fuels faster than we are burning them. Your example about Brazilian soils is especially informative. The reason more and more forest is slashed and burned is that rain forests have poor, shallow soils that depend on a short residence time of carbon. That is, they depend on high turnover of leaf litter etc to support high biomass. They do not have deep reserves of buried organic matter and once the biomass is removed and you can take only a few seasons of crops (grain and/or cows fed on the grain) before the soils are exhausted.
121560. Doug Mackie at 10:39 AM on 4 April 2010
        A residential lifetime
        Johnd @54 Huh? Sorry, I seem to be especially obtuse lately. Do you mean to ask if: Given that there is so much concrete etc with a lot of thermal inertia then will the concrete soak up a lot of the excess heat that would otherwise warm the atmosphere? And/or will the slow release of such stored heat alter the climate? The answer is simple and can be phrased as a question: “Why are wine cellars cellars?” Hint #1: What should you wear in a desert at night? Hint #2: Compared to concrete, what is the heat capacity of water? Or soil? Or sand? How much of each is there on earth?
121561. Riccardo at 10:02 AM on 4 April 2010
        Temp record is unreliable
        johnd, it's always a good thing when other scientists come out with different analysis. But it needs to be done at the same quality level. The dataset Spencer uses did not go through the same quality control as GHN; also, data are not homogenized. Spencer corrected the raw data just for altitude and check for water coverage. Given that similar and more comprehensive analysis on the link between population and UHI has already been performed and accounted for, I'd be more carefull before claiming that "there is sufficient doubt". There are other things that I think need to be clarified. For example, Spencer found large UHI warming-population density differences for different years, which I find hard to explain. Even larger differences are found between USA and the rest of the world. Also, there's a sharp increase in the warming bias already between population densities of 5 and 20 per Km2, which again I find hard to understand. And it's worth noticing that the whole claim is based on the data for population densities below 200 per Km2, above which Spencer's results agree with CRUTem3. Spencer should also explain how satellite based temperatures can be fooled by population density. One last remark, the ISH dataset is released by NOAA which uses the GHN dataset for its analysis of temperature trends, I'm sure for good reasons.
121562. Ned at 09:39 AM on 4 April 2010
        There's no empirical evidence
        philc, here's a simplified way to think about it: (1) In the pre-industrial atmosphere, total solar irradiance is in balance with outgoing longwave radiation, giving the earth some normal temperature T. (2) When we add CO2 to the atmosphere, this reduces outgoing longwave radiation in the CO2 absorption bands. (3) The earth then warms, causing more radiation to be emitted in wavelengths that aren't absorbed by CO2. (4) Eventually, outgoing radiation is again in balance with the incoming radiation, but with less of it being emitted in the CO2 absorption bands, more of it being emitted outside those bands, and a higher surface temperature. This is not actually a perfect description of what's going on, but it's fine at the conceptual level IMHO.
121563. Harold at 09:31 AM on 4 April 2010
        A database of peer-reviewed papers on climate change
        doug_bostrum, you may be right that his tone and attitude reflects a lack of respect that is not helpful. I am not Ross McKitrick and have not spent the two years dealing with the inexplicable responses and nonresponses from referees and editors that has eroded at that respect. I also have no experience trying to publish technical papers in journals, and so I do not know what is normal in the back-and-forth of peer review. You have implied that this is the standard experience of many people in Climatology and other fields. I would like to ask generally of those who have published in peer reviewed journals if the experience of Ross McKitrick described in this essay<\a> is commonplace. I appreciate the stance of this blog and this thread in that science expressed in peer reviewed papers should be allowed to speak impartially. However, this article throws another light on peer review. If McKitrick's experience is rare, then science is not allowed to speak impartially, and given the significance of AGWs implications, this is a critically harmful situation. If McKitrick's experience is commonplace, then peer review itself is broken, and science needs to find another voice.
121564. johnd at 09:03 AM on 4 April 2010
        Temp record is unreliable
        Some recent analysis of USA surface temperatures, 16th March 2010, by Dr. Roy Spencer (http://www.drroyspencer.com/category/blogarticle/) suggests that there is sufficient doubt and perhaps significant differences to be found when closely examining the published data that warrants closer examination to accurately quantify the UHI effect, and how it impacts on both the accepted trends and also on how it affects other data that was calibrated against accepted surface measurements.
121565. Tom Dayton at 09:02 AM on 4 April 2010
        There's no empirical evidence
        philc, see John Cook's "Response" in the green box below this comment.
121566. johnd at 08:57 AM on 4 April 2010
        A residential lifetime
        Tom @62. Thanks, I had read that discussion some time ago, but I see that it has had some recent additions. I'll post the link I provided above onto that discussion as it is more recent than any of the postings there.
121567. philc at 08:47 AM on 4 April 2010
        There's no empirical evidence
        "Satellite and surface measurements find less energy is escaping to space at CO2 absorption wavelengths. " It would seem to me that the total radiation outgoing is the critcal number. Of course CO2 would absorb in its natural wavelengths, but that doesn't mean an equal amount of energy isn't going out at other wavelengths.
121568. Tom Dayton at 08:29 AM on 4 April 2010
        A residential lifetime
        johnd, surface temperature measurements are off topic. If you want to continue discussing that, you should do so on the appropriate thread: Temp record is unreliable. (I suggest you read that posting and the existing comments on it first.)
121569. johnd at 08:24 AM on 4 April 2010
        A residential lifetime
        Philippe Chantreau @60, some recent analysis of USA surface temperatures by Dr. Roy Spencer (http://www.drroyspencer.com/category/blogarticle/) suggests that there is sufficient doubt and perhaps significant difference that warrants closer examination to accurately quantify the UHI effect. As a matter of interest, and to put it into perspective, is there any data that indicates the total weight of manmade structures world wide that would qualify as thermal mass? GFW @58. Are not albedo and thermal mass merely different sides of the same coin especially when dealing with the UHI effect?
121570. Philippe Chantreau at 06:13 AM on 4 April 2010
        A residential lifetime
        "the UHI effect which is significant enough to perhaps inflate global average surface temperatures" There is no credible evidence for this. The trends for urban areas aren't significantly different from rural areas. See this post, which references the papers listed below. http://www.skepticalscience.com/urban-heat-island-effect.htm http://pubs.giss.nasa.gov/docs/2001/2001_Hansen_etal.pdf http://www.ncdc.noaa.gov/oa/wmo/ccl/rural-urban.pdf http://journals.ametsoc.org/doi/abs/10.1175/JCLI3730.1 http://www.agu.org/pubs/crossref/2008/2008JD009916.shtml GC, your irrational fear mongering with things like the earlier "pestilence" (already adressed) or that new "horrific famine" is getting tiresome. It seriously undermines your argument, whatever that is. That kind of gross exaggeration, completely divorced from reality, is fine in tabloids or clumsy attempts at manipulating the public. Take it to that kind of forum.
121571. Doug Bostrom at 05:48 AM on 4 April 2010
        A database of peer-reviewed papers on climate change
        Harold,quite frankly to me Dr. McKitrick's essay is to me evidence only that he feels upset that his work was not published in the journal of his choice and has chosen to make his wounded feelings public. Even the amount of effort he's clearly devoted to constructing his "case" in such granular and almost obsessive detail is striking in a way that reflects poorly on Dr. McKitrick. It is actually surprisingly juvenile in tone and attitude, such his catty asides about Benestad. As to the merit of his charges, I read nothing in the work that could not describe the experience of a myriad of other researchers working on less controversial topics. Perhaps McKitrick has been treated somewhat more critically than other workers, but then his own posture and history of remarks about other researchers almost invites that. "Circling the Bandwagons" may be an effective title choice when talking to a private audience, but as an invitation to serious consideration by others it fails. Meanwhile, McKitrick's conclusion that "the IPCC used false evidence to conceal an important problem with the surface temperature data on which most of their conclusions rest" is hyperbole in the extreme and of course relies on the reader failing to remember that McKitrick's analysis (which he himself admits was flawed) dealt with but a single type of data from the plethora of research threads incorporated into IPCC's work.
121572. GFW at 05:20 AM on 4 April 2010
        A residential lifetime
        @55 John R. Yes, on very long time scales, there has been a net flow of carbon *through* the soil into fossil fuels. But that flow rate is very low. Other than that, what the soil takes up, it gives back (or else all the carbon would wind up in the soil, which obviously hasn't happened). So, while the woods near you may be building soil, there are other places in the world where soils are shrinking. Absent man, soil would be in pretty good equilibrium, except for that tiny net flow to fossil fuels. You are right that the size of the soil carbon reservoir is larger than that of the air (and smaller than that of the ocean). As long as near-equilibrium is maintained, that doesn't matter. However, one very possible concern is that because of human interference, the soil reservoir will shrink, pushing carbon into the air. Specifically, deforestation in tropical to temperate regions, and warming of soil/permafrost in subarctic regions are processes that have the potential for a significant transfer of carbon from the soil to the air.
121573. GFW at 05:05 AM on 4 April 2010
        A residential lifetime
        Apologies. My #57 was in response to #50, which I now see was also answered at #53. Heh, considerable similarity in points made - scientific understanding is consistent. To add value, I'll respond to #54. Thermal mass of anything on land is tiny compared to the thermal mass of the ocean. Also, adding thermal mass in some location while holding other factors the same will in general produce a moderation of temperature extremes, e.g. warmer nights and cooler days. The UHI has very little to do with thermal mass, and very much to do with albedo. Blacktop, dark roofs, and the three dimensional topography of buildings make a city a much better absorber of sunlight than natural landscapes are.
121574. Harold at 04:54 AM on 4 April 2010
        A database of peer-reviewed papers on climate change
        doug_bostrom, in your response to my observation in (19) that 'peer review is not necessarily a level playing field', you note that McKitrick was dismissive of Benestat as a blogger when he is a highly credentialed scientist. However, in context, Benestat is a 'blogger at realClimate.org' (whose byline is "Climate science by climate scientists") who objected to the way that McKitrick's paper handled spatial autocorrelation. This suggests to the credulous reader that Benestat probably has more credentials than most bloggers. I suspect that McKitrick does not share your opinion on the relative difference between a highly credentialed scientist and a mere blogger - he is a credentialed academic and a university professor who has co-authored papers with a 'blogger'. You further note that McKitrick 'jumps directly into characterizations of others' work as "fabrications"'. Actually, the only time he uses the word 'fabrication' is in reference to a paragraph in an IPCC draft that dismisses his work with misleading citations and an unsubstantiated assertion (which he explores and writes a paper to show is incorrect). I believe that the reason these items in McKitrick's article feel like 'rank hyperbole' is because he is casting a shadow on people you respect, and I probably would feel the same. However, this thread is about peer reviewed papers, and regardless of who is right in the AGW debate, McKitrick's article is first person evidence that the implications of papers on AGW affects peer review. Phil Jones' email about 'redefining peer review' is additional evidence. You mention that that you were going to 'leave the question of whether he was fairly treated in the hands of other, more easily believed folks, such as editors and reviewers with sufficient proven reliability to be found working for reputable journals.' Their reliability and absence of bias is precisely the question at hand. McKitrick gives personal experience as evidence
121575. GFW at 04:51 AM on 4 April 2010
        A residential lifetime
        Water vapor will respond to, and amplify any change in temperature, (although with the proviso that to amplify an upward change, there must be a source of water vapor). I would *suspect* that there is enough water vapor emitted in a city in exhaust and respiration for that to work.(**) However, while the UHI is locally important, averaged over the planet's surface it is tiny compared to the CO2 forcing. (**) There's a lot of other things going on with a city though. It's not just a heat island, it's a pollution island. Ground level ozone, aromatic hydrocarbons, NOx, ... you'd have to ask an atmospheric chemist specializing in such matters if those have any effect on urban humidity.
121576. gallopingcamel at 01:56 AM on 4 April 2010
        A residential lifetime
        doug_bostrom (#51), My post that John deleted related directly to your point. I will try again after pausing to show that this post is "on topic". On this thread we are discussing the "Residence Time" of CO2 in the atmosphere, so it seems relevant to consider whether mankind can affect this in any way. Most of us accept the idea that CO2 concentrations are in fact rising owing to human activity. The sequestration issue is the other side of the same coin. Can mankind reduce CO2 concentrations? In my opinion the answer is clearly YES and there are plenty of strategies for doing so that I would support. Doug's idea of storing non-perishable food in Tupperware is probably the best of all. Governments should provide incentives to farmers to produce non-perishable food mountains instead of the perishable "Butter Mountains" and "Wine Lakes" created by the European Economic Community. This will help reduce the horrific famines that will occur during the next "1816" (The Year Without a Summer). This is not science fiction; enlightened governments have used this strategy all the way back to biblical times. It used to be called "Building Granaries" rather than "Sequestration". Where can one find a Hammurabi in this modern world?
121577. John Russell at 00:57 AM on 4 April 2010
        A residential lifetime
        Doug Mackie @52. According to Wikipedia, (under the heading 'Soil Carbon') "over 2700 Gt of carbon is stored in soils worldwide, which is well above the combined total of atmosphere (780 Gt) or biomass (575 Gt), most of which is wood." I would say that counts as significant; don't you? I stand by my statement that natural biological processes -- if left alone by man (a critical qualification) -- will tend to build up the carbon content of the soil. I see this in my indigenous (to the UK) wet woodland year on year as rotting trees and leaves fall into the mud where only a few inches down it can become anoxic. Let's face it, this is how the fossil fuels formed in the first place. Note that I am not claiming that, left alone, soils can sequester all of our fossil fuel emissions -- can anything? -- but they do pull in the right direction. In Brazil I, personally, have witnessed deep, rich, soil full of organic matter being reduced to little more than sand within a decade or so, once it has been exposed by deforestation and turned over to agriculture. Forestation and even sustainable agricultural practices, if managed correctly, can sequester significant amounts of CO2. My point is that it can be more than just a temporary store while the trees/plants are growing, as your article suggests.
121578. johnd at 19:21 PM on 3 April 2010
        A residential lifetime
        Doug Mackie @ 53, thank you for indulging me. What I am asking is whether the billions? trillions? of tonnes, and ever increasing, thermal mass of manmade infrastructure has as much effect of storing heat energy as atmospheric CO2, thus also providing radiative forcing. The residential lifetime of such structures would generally exceed that of atmospheric CO2. Just a simple example to illustrate. Most brick, stone or concrete structures are built inside out with the thermal mass on the outside, insulated from the inside. When a structure is built with the thermal mass on the inside it modifies the internal climate due to the thermal mass both absorbing and dissipating heat energy albeit on a small scale. However structures built with the thermal mass on the outside have been built all over the planet on a massive scale and the effect is measurable as the UHI effect which is significant enough to perhaps inflate global average surface temperatures.
121579. Riccardo at 18:26 PM on 3 April 2010
        Greenland's ice mass loss has spread to the northwest
        HumanityRules, both are affected by rising temperatures but this is about the only relation between the two. They behave differently, as nicely and concisely explained by GWF.
121580. Doug Mackie at 18:11 PM on 3 April 2010
        A residential lifetime
        Johnd @50 Would the Urban Heat Island effect also qualify as a driver of water vapour? It certainly is measurable and widespread. This too is veering away from lifetime/residence time. However I shall indulge you, though without emoticons I am not sure you are serious. Do you mean to ask: “Do cities produce enough extra water vapour have the potential to control/change climate to a significant extent compared to extra water vapour in the atmosphere from general global increase in temperature”? If that is what you meant then no. The AR4 FAQ 1.1, 1.3. 2.1 and 3.2, and the main text they point to, answer this comprehensively and there is no point me pasting the text here. The issue is radiative forcing
121581. Doug Mackie at 17:53 PM on 3 April 2010
        A residential lifetime
        #34 John Russell (Sorry to anyone who has already read this comment: This is a repost. I am a potty mouth and John has made me delete bad words from the original. Where they are not being depleted by agriculture or deforestation the world's soils are all constantly deepening. No. This is false. As I said: with the exception of fossil fuel formation the carbon cycle is efficient at recycling carbon. Where precisely do you think significant accumulation is occurring? Please read TAR and AR4 on the subject of soils. There are certainly uncertainties but there is no way that soils can sequester a significant portion of fossil fuel emissions. My solution: Take a few unpopular low lying cities and flood them. Grow trees there. When mature, bulldoze the trees and repeat. It is essential to maintain anerobic conditions to promote peat/coal formation. Re the CO2 lifetime. I think the discussion tends to over-complicate a simple concept. The claim made by denialists is that CO2 has a short residence time and thus, they claim, cannot possibly cause warming over the 500 year timeframe discussed by IPCC. That is male cow excrement (can you guess what the offending word was?). Pure and simple. Through ignorance, malice, or both the denialists confuse lifetime with residence time. You go on to paraphrase my argument (that residence time is irrelevant) so I am not sure what your point is.
121582. Doug Bostrom at 17:38 PM on 3 April 2010
        A residential lifetime
        GC, I think someone could write an interesting science fiction novel, entailing a plot wherein inhabitants of a planet with insufficient greenhouse gases are facing an ice age and discover (a hero is forced to jump through hoops to enlighten his fellows, natch) enormous hydrocarbon reserves, sufficient if extracted and burnt to bring things into balance. Evildoers attempt to thwart the plan by suggesting that these hydrocarbons are instead used to manufacture something called "Polyware", storage containers for mountains of excess food, but are ultimately thwarted. The hero basks in warmth and affection at the end of the book. But that's science fiction, as I said. The situation we face is unfortunately the opposite, but we could still sequester hydrocarbons in actual Tupperware(tm) if we chose and in this version of the plot the folks recommending the combustion method do not play the role of protagonists.
121583. johnd at 15:48 PM on 3 April 2010
        A residential lifetime
        Doug Mackie @ 47 re "Point is that water vapour is the result of temperature while CO2 causes temperature" My point was/is, CO2 is not the only mechanism that can alter temperatures that water vapour may respond to. Would the Urban Heat Island effect also qualify as a driver of water vapour? It certainly is measurable and widespread.
121584. Tom Dayton at 15:30 PM on 3 April 2010
        A residential lifetime
        I believe that delaying the next ice age is off-topic for this "residential lifetime" thread. Gallopingcamel, you would be a more constructive commenter if you posted your comments in the appropriate threads instead of whichever one you happen to be reading at the moment.
        Response: I have deleted one of Gallopingcamel's recent comments for being off-topic. However, an upcoming ice age is somewhat on-topic in the sense that residential time of CO2 does affect whether we can fall into an ice age any time soon. Archer's studies find that a significant chunk of the CO2 we emit will remain in the atmosphere for thousands of years hence an ice age is indefinitely postponed.
121585. gallopingcamel at 15:17 PM on 3 April 2010
        A residential lifetime
        John Russell (#40), Thanks but I can't accept credit for the idea that the next Ice Age can be delayed if we put 5,000 Gtonne of C into the atmosphere. Two men deserve the credit, namely Archer and Ganopolski. I have been very careful to avoid offering an opinion on A&G's analysis. I was hoping to get a few insights from the clientele on this blog. Should we try to delay or accelerate the next Ice Age? Would the idea work? I do not buy Ned's argument that the next Ice Age is so remote in time that we don't need to think about it.
        Response: An ice age is only possible if northern ice sheets grow from year to year. So if you see a gigantic ice sheet creeping down northern Canada, then yes, it's time to start worrying that we're heading into a new ice age. For now, I think you can relax about an impending ice age (or as my daughter likes to say to me, chillax). Ice sheets can collapse relatively quickly because ice dynamics cause glaciers to slide faster into the ocean. But the speed that ice sheets can grow is limited by the amount of snow falling each winter.
121586. Doug Mackie at 15:05 PM on 3 April 2010
        A residential lifetime
        #42 John D Point is that water vapour is the result of temperature while CO2 causes temperature. AR4 FAQ does this in simple terms. As soon as water vapour concentration gets too high it rains. #43 John D The issue is timing. At glacial onsets/terminations it takes at least 10,000-15,000 years for CO2 to decrease/increase by ~100 ppm (and temperature change by ~10 decC). We have increased CO2 by 100 ppm (over and above the "usual maximum" of 280 ppm) in just 200 years. Temperature lags (but will follow CO2) and ecosystems are struggling to keep up with the rate of change.
121587. Doug Mackie at 14:54 PM on 3 April 2010
        A residential lifetime
        #36 Gallopingcamel Mammals predate dinosaurs and lived in their shadows for 160 million years. After the KT event birds (poncy dinosaurs) dominated in many ecosystems. Mammals were very late starters. Mammalas have less advantage in warm conditions but do have an advantage in colder conditions. (e.g. Think cold morning start up time).
121588. Doug Mackie at 14:32 PM on 3 April 2010
        A residential lifetime
        #33 RSVP Bugger. Note to self: Use emoticons. My comment re NH air conditioning was jocular. Energy use is not likely to change voluntarily. As Working Group II reports make clear: Warming will be good for a few people. E.g. (maybe) Canadian and Siberian grain belts. However, it isn’t it obvious that if, for example, the USA/China endured dust bowl conditions then they would pay what the Canadians/Russians asked to avoid their people starving. I mean, sure they have nukes and all that but they would never.... Would they?
121589. scaddenp at 13:50 PM on 3 April 2010
        A residential lifetime
        What is so hard about seeing the difference between a cooling over 10,000 years and warming over 150 in terms our capacity to adapt? If you are so desperate to avoid an ice age, then we should immediately sequester all fossil fuel so that 3000 years down the track, there will be something to burn for atmosphere enrichment. Frankly it seems to more like clutching at straws - believing anything rather than accept the need to deal with the problem.
121590. johnd at 13:14 PM on 3 April 2010
        A residential lifetime
        John Russell @34, it is clear from the vast deposits of coal that a tremendous amount of CO2 was stripped from the atmosphere by plants. As CO2 concentrations fell, so too would temperatures as well as plant growth until a glacial period took hold. At that point with plant growth almost stalled or plants dead or dying, the process of stripping atmospheric CO2 would be at a point where decomposition of plant amterial would begin releasing previously sequestered CO2 producing conditions to allow for a recovery from the glacial conditions.
121591. johnd at 13:00 PM on 3 April 2010
        A residential lifetime
        robhon, if water vapour responds so strongly with positive feedback to a relatively minor change in CO2 concentration, then it must also respond as strongly directly to any changes in temperature brought about by the Milankovitch cycles, even without any changes in CO2.
121592. GFW at 11:21 AM on 3 April 2010
        Greenland's ice mass loss has spread to the northwest
        HR, yes there appears to be *some* linkage between sea ice and the glacier flow/calving rate, but it's not quite the same story as how the more permanent ice shelves of Antarctica hold back glaciers there. Sea ice doesn't have the thickness or rigidity of an ice shelf so any back-pressure effect is much weaker. However, the less sea ice there is in general, the less protection Greenland has from warm winds and currents.
121593. HumanityRules at 09:56 AM on 3 April 2010
        Greenland's ice mass loss has spread to the northwest
        Riccardo #54 Is sea ice extent really unrelated to this topic? If it's true that most of the mass loss is due to calving rather than melting in-situ as suggested by many then surely open ocean for longer time periods must have an affect on the rate of ice loss. It would seem common sense that open water facilitates more calving than ice locked sea. The many animations of arctic sea ice suggest there has been change in sea ice freeze in the Baffin/Greenland sea since the 1980's.
121594. Rob Honeycutt at 08:03 AM on 3 April 2010
        A residential lifetime
        @HenryH... You should really watch the Richard Alley lecture that John suggested. It explains the whole issue extremely well. Google: Richard Alley The Biggest Control Knob. The point that Alley makes in the lecture is that Milankovitch cycles can only account for a small portion of temperature change. It's those cycles of orbit, precession, etc that set off feedbacks in CO2 and CH4 that result in the swings in global temps that we see.
121595. Philippe Chantreau at 05:13 AM on 3 April 2010
        The human fingerprint in global warming
        RSVP "For instance, life (as we know it) cannot be sustained without oxygen." That's incorrect. The oxygen in our atmosphere is owed to living organisms. Numerous organisms still exist that do not need oxygen. See for example this: http://www.scientificamerican.com/article.cfm?id=origin-of-oxygen-in-atmosphere
121596. John Russell at 04:33 AM on 3 April 2010
        A residential lifetime
        I like 'gallopingcamel's' suggestion that humans raising the temperature by a few degrees is acceptable on the grounds that we're pre-empting an ice-age that might possibly affect us, to some unknown degree, at some unknown point in the future! If only sceptics were as willing for humans to take dramatic actions to lower temperature by reducing emissions, in the face of the suggested 95% chance that increased temperatures will destroy our children's future.
121597. Ned at 03:59 AM on 3 April 2010
        A residential lifetime
        gallopingcamel writes: I am a little puzzled by your conclusion that a warmer earth would be "inhospitable" given that mammals became dominant during the Eocene when temperatures were much higher than today. Our agricultural system and all our infrastructure are predicated on the idea that climate is more or less constant, such that if the north-central US is a good place to grow wheat now, it will continue to be a good place to grow wheat in the future. Or, as another example, we build a fleet of ships/barges to operate on the Mississippi River or the St Laurence Seaway, with the assumption that water levels will not drop enough to prevent fully laden vessels to move through the system. In other words, there are a million ways in which our infrastructure is designed around a particular climate in particular places. Changes in temperature or more importantly precipitation can wreak havoc with this. You keep arguing that a few degrees of warming is OK because "it's better than another glacial advance." But no one is suggesting we should try to create another round of glaciation! The question isn't "Which is worse, too warm or too cold?" The question is "Which is better, the climate we have built our infrastructure around or a climate that's significantly warmer most places, with very different patterns of precipitation?" Please stop using a non-existent threat of rampaging glaciers as an excuse to ignore the actual threats associated with CO2-driven climate change.
121598. John Russell at 03:28 AM on 3 April 2010
        A residential lifetime
        Tom Dayton: I know, I know; hence my point 2 about the hole in the bucket (...dear Lisa, dear Lisa). I thought it worth making the point about the wider ability of naturally-occurring vegetation to sequester CO2 when left alone to do its thing, which many people choose to overlook. The irony is that not only are humans adding to atmospheric CO2 but -- through a lack of understanding -- we're also blocking the ecosystem's correcting mechanisms which have evolved to protect the existence of life on the planet. This is the basis for Lovelock's 'Gaia' theory.
121599. Tom Dayton at 02:24 AM on 3 April 2010
        CO2 has a short residence time
        I agree with you in general, Hugh. It is best to avoid repeating misinformation even in the context of disproving it, because repeating the disinformation actually publicizes it. That's why I greatly appreciate Doug's approach in this post, of stating the facts. But there is also the problem of icons such as this sacred list of 36 previous studies. That list is used by deniers as evidence that 36 other experts disagree radically with Doug and "a few" other people. That tactic could be neatly parried by saying that all those studies were about residence time of an individual molecule rather than adjustment time. Such a simple statement inserted as a single sentence in Doug's description of residence time would help a lot, I think. But we'd have to be sure such a statement was completely accurate, which is where a student project would be helpful.
121600. Tom Dayton at 02:10 AM on 3 April 2010
        A residential lifetime
        John Russell, the problem is that sequestration by trees (and plants in general) cannot keep up with CO2 increases due to humans. On the relevant thread CO2 Is Not a Pollutant there are some relevant comments containing links to sources: #3 by me followed by #4 by muoncounter. See also the USDA report I linked to in my comment #1 on that thread.

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