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Comments 119301 to 119350:

119301. scaddenp at 12:57 PM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        Well I doubt even centuries away really. Surely with even our most destructive impulses, we are going to have job maintaining a BAU CO2 emission strategy beyond 2100 even if run it till there.
119302. Bern at 12:45 PM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        @Joe Blog at #34: I don't know, some quick google-fu didn't help me out either. Can someone with access to the full article check for a reference for that figure? But this NASA page has lots of information about the heat conductivity & capacity of a typical human body (and they're talking about astronauts, so people in good physical condition). Presumably, it's possible to calculate from this (and lots of other thermodynamics) what the maximum survivable temperature is. Note, also, that there's a time-frame associated with it - you can endure high wet bulb temperatures for some time, with appropriate precautions (hydration, shade, rest), but if it goes on for too long your core temperature will rise too high and you'll be in trouble, as you mentioned.
119303. Rob Honeycutt at 12:30 PM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        @HumanityRules... If I'm not mistaken late cretaceous mammals were limited to early marsupials and other rodent-like creatures. Not a huge mammal population.
119304. Bern at 12:06 PM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        @Humanity Rules at #33: Isn't current global average temp more like 15ºC? That would but the entire Cretaceous at less than 7ºC higher than current. But just because some species of mammals have survived through that time-frame doesn't mean they weren't highly restricted in their range - mountain tops, high latitudes, other areas with cooler-than-average climates. Re the Mumbai comment - I rather suspect increases in Indian life expectancy have more to do with hygiene, nutrition, and modern medicine than temperatures. If we see this sort of nearly-worst-case warming, then life expectancy for India would start to plummet again in a few hundred years. @Berényi Péter at #32: you're right, 41ºC with 13% RH is only a wet-bulb temperature of 20ºC. But the same issues that resulted in so many deaths (heat stress, dehydration) under those conditions will, of course, only get worse as temperatures rise further. If increasing global temperatures result in more water vapour in the atmosphere, then the RH is likely to be the same or higher. The point of this posting, though, is that with sufficient increases in global temperatures, we might find areas where the heat waves are not survivable by humans, irrespective of how well hydrated you are. The frail, elderly, and sick would be the first to succumb, most likely well before we reached that cut-off point, even with the best of care. All this is assuming the absence of air-conditioning, of course, but not many people outside the US have that (although it's becoming much more common here in Australia). And even if you did, you're only a power failure away from big trouble. Moving underground (or using ground-loop heat exchange with extremely well-insulated buildings) might be the only way to cope in the affected areas. It's still most likely centuries away, though, so there's time for technological adaptation to cope with such extreme heat waves.
119305. Joe Blog at 12:03 PM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        Bern, thanks for the reply, unfortunatly there is no comparison between Darwin and Suai(it really is a hell hole).. but according to those tables i must have been in temperatures above this 35... there were no real weather stations mind. This was going of the battalions station they had set up on the edge o the main base, basically in jungle/grassland. So dont really know how accurate it was, hottest day tipped the mercury at 52 though. But to put this wet bulb in context... basically this paper is saying that someone submersed in 35c water for an extended period will die from heat stroke? i suppose i can see yer bodies metabolism easily enough throwing in the extra 5-7c for it to be fatal.(when yah core hits 40, its like yer on acid.. and aint long after that yah twitchin on the ground) But i do have to say, i have big doubts as to the accuracy o this claim. Speaking for myself, in those upper temps, i was drinking 15-20liters a day, which was warm, but still cooler than yer body temp. Im not going to pay to read the paper. But how exactly did he determine this survivability level?
119306. chris at 10:42 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Tiny error in my long post just above. Though no one will likely notice, under (ii) it should say: "If there is a very fast negative feedback, then the increase in TOA IR will be more than this."
119307. chris at 10:37 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Berényi Péter at 07:22 AM on 13 May, 2010 Although the moderator doesn't like Peter Berenyi's post here, I would have thought it was appropriate. After all the thread is about Earth climate sensitivity and that's what Peter's post is about. So in the assumption that posts about climate sensitivity are O.K. (as opposed to digressions into "waste heat"!), I'm going to respond to Peter. A problem with your post (Peter) is that the conclusion ("Therefore we should look for some explanation...") is built on a set of premises some of which are unlikely to be justified: (i) It's worth stating from the outset that Spencer and Braswell don't conclude anything about the Earth climate sensitivity from their paper in press that you refer to, and in fact state explicitly that their analysis doesn't necessarily have any bearing on Earth climate sensitivity as commonly regarded (the change in Earth surface temperature at equilibrium in response to radiative forcing equivalent to a doubling of atmospheric [CO2]; see bottom of post [***]). Nowhere in their paper do they suggest that the climate sensitivity is 0.5 oC (they don't conclude a climate sensitivity at all). I think you may have fallen for blogosphere over-interpretation, whereby someone pretends on his blog that a paper means something that it doesn't actually mean! So your major conclusion ("Therefore we should look for some explanation...") is invalid (non-sequitur). (ii) It’s also worth having a look at what Spencer and Braswell have actually done. One can usually get a good idea by looking at the abstract; it's reproduced at the bottom of this post [*****]. A previous analysis (Forster and Gregory, 2006) has made a much more substantial and quantitative analysis of this subject with a good discussion of the problems, and is rather more understandable than Spencer and Braswell. The aim is to make the most direct measure of feedback by direct analysis of the combined long wave IR emitted from the earth surface (and shortwave IR reflected by the atmosphere) in response to changes (fluctuations) in the measured sea surface temperature. If the temperature rises, the change in emitted IR (measured at the top of the atmosphere by satellites; TOA) should be equal to the “blackbody” radiation determined using the Stefan-Boltzmann relationship in a system with no very fast feedbacks. This is around 3.3 W.m-2.K-1. In other words just as the Earth should warm by around 1.1 oC per doubling of [CO2] with a climate system with zero feedbacks, so an Earth temperature rise of around 1 oC should result in an enhanced IR emission of 3.7 W.m-2 as the climate system “tries” to recover radiative equilibrium. If there is a very fast positive feedback the change in emitted IR will be less than this (because the positive feedback acts to "trap" some of the LWIR escaping to space). If there is a very fast negative feedback, then the increase in TOA IR will be less than this. Forster and Gregory found that the change in TOA IR is 2.3 +/- 1.4 W.m-2.K-1, (i.e. positive feedback since the change in TOA emission is less than the blackbody value), consistent with a (fast) climate sensitivity response of 1.0 – 4.1 oC per doubling of [CO2]. i.e. unfortunately poorly constrained. (iii) Spencer and Braswell use a variation of this in which they compare monthly averages of sea surface temperatures with monthly averaged satellite TOA measures and make regressions of the data to pull out a TOA radiative response to temperature changes. At this point their analysis becomes somewhat obscure (to me anyhow), and they compare the patterns of their regressions with model data and identify “striations” and “spiral patterns”. Their apparent change in TOA emission is 6 W.m-2.K-1. However (see [***] below), they conclude that this doesn’t necessarily relate to a climate sensitivity. (iv) There is an inherent problem with the claim of a negative fast feedback (Spencer claims this on his blog even if he doesn’t in the paper) and this relates to the fact that the fast feedback is bound to involve water vapour. There is no question that the atmosphere responds to warming with an increase in absolute humidity (see papers on this here ). So there really has to be a positive feedback to the warming from enhanced [CO2] with respect to water vapour. Cloud changes could provide a fast feedback (and presumably that is where Spencer and Lindzen – although the latter’s analysis was incorrect – would source their putative negative feedback). However Forster and Gregory conclude (with poor certainty) that the cloud response was neutral over the time of their measurements. The only other direct analysis of cloud feedback concludes that the cloud feedback is positive (over the NE Pacific anyhow!) (v) Finally, the temporal evolution of warming since the middle-late 19th century rather precludes negative feedbacks (clouds or otherwise) on the timescales relevant to climate sensitivity. Since we’ve had around 0.9 oC of warming during this period in response to enhanced [CO2] (290 ppm – 388 ppm) which should give around 0.4 oC of warming at equilibrium with a climate with zero feedbacks (let alone negative feedbacks) , significant negative feedbacks seem very unlikely (after all where have they been??), particularly as the solar contribution to this temperature rise is likely no more than 0.1 oC, and that some of the enhanced greenhouse warming has been offset by anthropogenic aerosols . Of course analyzing this properly requires a proper analysis! (try e.g. here, or here ------------------------------------------------- [***]e.g. Spencer and Braswell conclude:

        "Although these feedback parameter estimates are all similar in magnitude, even if they do represent feedback operating on intraseasonal to interannual time scales it is not obvious how they relate to long-term climate sensitivity."

        and

        "Since feedback is traditionally referenced to surface temperature, extra caution must therefore be taken in the physical interpretation of any regression relationships that TOA radiative fluxes have to surface temperature variations."

        [*****] abstract: “The impact of time-varying radiative forcing on the diagnosis of radiative feedback from satellite observations of the Earth is explored. Phase space plots of variations in global average temperature versus radiative flux reveal linear striations and spiral patterns in both satellite measurements and in output from coupled climate models. A simple forcing-feedback model is used to demonstrate that the linear striations represent radiative feedback upon non-radiatively forced temperature variations, while the spiral patterns are the result of time-varying radiative forcing generated internal to the climate system. Only in the idealized special case of instantaneous and then constant radiative forcing -- a situation that probably never occurs either naturally or anthropogenically – can feedback be observed in the presence of unknown radiative forcing. This is true whether the unknown radiative forcing is generated internal or external to the climate system. In the general case, a mixture of both unknown radiative and non-radiative forcings can be expected, and the challenge for feedback diagnosis is to extract the signal of feedback upon non-radiatively forced temperature change in the presence of the noise generated by unknown time-varying radiative forcing. These results underscore the need for more accurate methods of diagnosing feedback from satellite data, and for quantitatively relating those feedbacks to long-term climate sensitivity.”
119308. Berényi Péter at 10:21 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        #105 Moderator Response: The right place to post this comment should be Climate sensitivity is low. I see. In reply to an article claiming climate sensitivity to be high, anyone who thinks otherwise should post comments elsewhere. Makes sense.
119309. HumanityRules at 10:17 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        According to Wiki mammals evolved 200+ million years ago. What you might call modern mammals have been around for over 100 million years. Here's a reconstruction of temperatures. Looks like mammals have lived through periods with global temps 10oC greater than now. According to Wiki upper ocean temps may have even touched 17oC above todays average during the Cretaceous. Do people not think there is a hint of alarmism about all this? Life isn't hell now so lets imagine a hell for future generations. It also ignores the possibility that humanity would do something about this. 15.mike roddy Things might get sticky in Mumbai but it seems nobody told the indians they should be dropping dead of heat exhaustion. Life expectancy in India has almost doubled in the past 50 years.
119310. scaddenp at 09:58 AM on 13 May 2010
        Hockey stick is broken
        John, another paper for you. Ice cover in Alps in 2003 at 5000yr low
        Response: That URL gives me a cookie error - is that a problem at my end or the publisher's?
        
119311. chris at 08:20 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        johnd at 07:14 AM on 13 May, 2010 "The need for postings to remain on topic is well understood.......The irony is....The subject is simply too....handy bite sizes..." Not really johnd. This thread is about an estimate of long term climate sensitivity based on analysis of CO2 temperature relationships 3 million years ago. Two people (you and RSVP) have chosen to sidetrack the thread into a tedious pretend "argument" about a very well understood subject (waste heat generation and its relation to Earth thermal energy balance). A pretence that we don't know what we do know about a subject doesn't equate to an indication that a phenomenon is inherently "chaotic". It just means that it is easy for posters on blogs to hijack discussions. It happens all the time, especially in poorly moderated blogs. The reality is that the natural world doesn't conform to one (or two) persons real or pretend ignorance of a subject. Likewise flooding threads with false arguments, pursuing inappropriate "analogies", and acting as if scientific knowledge hasn't progressed beyond the junior school level doesn't equate to "skepticism". Skepticism only really has meaning in relation to an informed and honest appraisal of a subject. In reality, while weather is "chaotic", the thermodynamics of radiative balance in the Earth system isn't. That's not to say that we understand everything - the range of likelihood in climate sensitivity (very unlikely to be below 2 oC per doubling of [CO2]; unlikely, but with greater uncertainty that climate sensitivity is greater than around 4.5 oC) is an indication of that. However the latter has got nothing to do with "chaos". It's largely to do with uncertainty in quantitating atmospheric aerosol forcings, cloud feedbacks and the various response times of the climate system.
119312. Berényi Péter at 08:16 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        #5 CBDunkerson at 21:38 PM on 11 May, 2010 The European heat wave of 2003 killed tens of thousands of people. The heat wave of 2003 has nothing to do with high wet bulb temperatures. It was worst in mid France. However, if you had a look at the weather history of Lyon, August 2003, you could see humidity was rather low on the hottest days. Dew point high there has never exceeded 21°C during August and when it was really hot (40°C on 12-13 August), relative humidity decreased to astonishingly low values (down to 12%). The high death toll is due to something else. Where people (and the government) are prepared for such a weather event, they can handle it pretty well. Unfortunately it was not the case in France. Most lonely elders died simply because they have not drunk enough water and relatives were out on holidays, not able to help them.
119313. Doug Bostrom at 08:12 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Johnd, regarding residency time there are scads of information on that topic liberally sprinkled hither and thither all over the Web, as well likely in your public library. Why do you want us to go through the exercise of repeating what has already been expressed hundreds if not thousands of times, available just a few keystrokes away? Make an effort. If you can't think of where to begin, consider starting here: Weart's Discovery of Global Warming
        
119314. johnd at 07:39 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Whilst the residency time of the various gases is often discussed, is it relevant? It is the residency time of the heat energy carried by the various gases and exchanged and transferred between the various gas molecules that is more important yet doesn't seem to be considered as something separate.
119315. Doug Bostrom at 07:35 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Not the case we're speaking of, johnd. Flipping the analogy is pointless.
119316. johnd at 07:32 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        doug_bostrom at 03:13 AM, whilst many people try to use a blanket as a simple analogy, that is making it too simple. For a start you need to clarify whether the house is on fire or not, because if it is, and your blanket slips off........ The greenhouse effect is not really a mechanism providing our comfort as a blanket usually does, but one providing us with protection, as a blanket also can, so a more useful analogy than a blanket would be a firefighters protective gear. So what happens if the firefighters jacket slips off?
119317. Berényi Péter at 07:22 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        #47 Riccardo at 17:37 PM on 11 May, 2010 there's no formal definition of slow or fast feedbacks, they must be considered relative to the time scale analyzed That's not an answer. It always bothers me that all kinds of feedback loops are discussed all the time without assigning proper time constants to them. For example atmospheric water feedback (including both vapor and clouds) has to be pretty fast. Residence time of water in the troposphere is about 9 days. Even in the lower stratosphere it is a month at most. It means it should respond to any changes in SST (Sea Surface Temperature) on this timescale. That is, if the water cycle is supposed to amplify CO₂ forcing threefold as claimed, we should be able to detect the effect even in short records (several years), we do not need many decades of data for this particular purpose. This is exactly what Roy Spencer is doing recently. His upcoming paper in the Journal of Geophysical Research will be an interesting read. Spencer, R. W., and W. D. Braswell (2010), On the Diagnosis of Radiative Feedback in the Presence of Unknown Radiative Forcing, J. Geophys. Res., doi:10.1029/2009JD013371, in press. (accepted 12 April 2010) He does not address water feedback directly, but claims to have found a strong short term (~1 month) negative feedback based on 7-9 years of NASA CERES radiation budget data. For detecting fast feedback loops that much data should be more than sufficient. On the other hand, it is hard to imagine that there could be a strong short term feedback in the climate system other than atmospheric water. At least no one has found one so far. Anyway, if short term (up to a month or so) feedback is negative, all feedbacks operating on longer time scales (years, decades, centuries, millennia) can only take this controlled signal as input. It means that any long term positive feedback loop that would bring temperature anomaly up to 4-5°C for CO₂ doubling as claimed by Pagani should supply a gain close to 10 (Dr. Spencer has found a 0.5°C short term equilibrium value for CO₂ doubling, as opposed to the 3°C IPCC "consensus" figure). With an f value of ~0.9 the climate system would be dangerously close to a runaway feedback (f > 1). In this case any number of slight structural changes over the ages could push it over the limit. As it has never happened in billions of years, there can be no such a strong positive feedback whatsoever on any timescale. Therefore we should look for some explanation of past excursions of climate other than carbon dioxide "forcing" amplified by multiple positive feedbacks of different origins operating on all timescales.
        Moderator Response: The right place to post this comment should be Climate sensitivity is low. Please always find the appropiate topic for your comments.
119318. johnd at 07:14 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        The need for postings to remain on topic is well understood for, each thread would quickly become chaotic, and people generally like to keep things neat and tidy not only in their minds, but in their forums as well. It has to be that way. The irony is that the matter being discussed, climate, is just the opposite, chaotic, and each individual factor somehow linked to interact with every other single factor. The subject is simply too vast and too complex for any single person to get their mind around, hence the need to break it down into handy bite sizes easily digestible, not only on forums such as this, but for the scientists as well. Ordered scenarios can be prodded and poked into a shape that than can be measured, and then modelled to yield results that reflect such an ordered system, but the focus is on the calculated outcome and the range of uncertainty essentially becomes off topic there also.
119319. WaxItYourself at 05:44 AM on 13 May 2010
        CO2 was higher in the late Ordovician
        A 2005 study shows that the late Ordovician glaciation actually occurred 10 million years before. This ice age did not occur when CO2 was at it's peak. Rather it began at a time when the concentration was between 180 and 200 ppm. http://geology.gsapubs.org/content/33/2/109.short
119320. Dikran Marsupial at 03:23 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        e says: "Long term processes such as rock weathering eventually start to remove CO2 from the atmosphere." I think the 200 year adjustment time is based on transfer of CO2 from the surface waters to the deep ocean, rather than chemical weathering, which acts on even longer time scales.
119321. Dikran Marsupial at 03:19 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        johnd says: "If CO2 has been calculated as having a long residency time, what is the residency time of water vapour." CO2 has a short residence time (4-5 years) but a long adjustment time (50-200 years). CO2 needs modeling rather differently to other GHGs due to the large annual exchange flux. "Even though there is a high turnover of individual molecules, water vapour as a gas has residency time beyond measurement, a permanent presence that will exist whilst warmth from any source rises from the earth's surface. " Water vapour doesn't have a residence time beyond measurement, IIRC it is a couple of weeks. As I understand it warm air holds more water vapour than cold air, so if CO2 radiative forcing falls, and air temperature with it, then water vapour will precipitate out and there will be less radiative forcing from water vapour as well. It is a feedback in both directions. CO2 is a permanent presence in the atmosphere in exactly the same sense that water vapour is.
119322. Doug Bostrom at 03:13 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP, you've got to make a stronger effort here. If by adding C02 to the atmosphere we cause it to be a more effective insulator, if we then remove C02 from the atmosphere we can expect it be a less effective insulator. In terms of net effect, this is simply insulation we're talking about. Do you live where it's necessary to have blankets on your bed? What happens when your blanket slips off? It's that simple. Please try a little harder.
119323. e at 03:07 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP, Long term processes such as rock weathering eventually start to remove CO2 from the atmosphere. As CO2 decreases the equilibrium temperature gets pushed down and the earth cools.
119324. Doug Bostrom at 03:05 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Ring-a-ding! Teachable moment. What I said: Surface insolation for Earth taking into account angle of incidence, atmospheric attenuation, diurnal cycle etc. is roughly 250MW/km2. The surface of the Earth is about 510,000,000 km2. So, about 127,500TW of total insolation. What RSVP perceived and concluded: doug_bostrom "surface of the Earth is about 510,000,000 km2. So, about 127,500TW of total insolation" You are taking the total surface area. Only one side of the Earth gets Sun at any given time, so you will need to at least half that result for starters and reduce some more to account for albedo. If we take the time to read a little more carefully and integrate new information, more progress in understanding becomes possible.
119325. RSVP at 02:57 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        John Why isnt waste heat in the list of skeptical arguments?
        Moderator Response: Not enough time to have written pages for all the arguments. The Links contain more. (Click the "Links" button in the horizontal bar at the top of the page.)
119326. RSVP at 02:54 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        Ned And aside from the question of what is causing global warming, you remark that the effects of CO2 will linger for 200 years even if CO2 levels were to stabilize. Assuming that the Earth's temperature were to actually increase 4 degrees 200 years from now. And assuming GHG did return to "normal" (say 250 ppm). What exactly should cause the Earth's temperature to come back to "normal", assuming all else being equal? Shouldnt it remain higher if equilibrium is maintained?
119327. Ned at 02:41 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        Right, IPCC always gives figures for warming by the end of the century (or 2095, in this case from AR4) but the warming won't stop there. 2095 is actually not that far away. Go back the same amount of time and you're in 1925 ... approximately when my parents-in-law were born. The average girl born in Japan this year will still be alive in 2095, the end point for the IPCC AR4 projections. That's pretty amazing when you think about it.
119328. Alexandre at 02:17 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        Ned #28 I find it important to stress that those ranges in your bottom box is just the projection for the end of the century. The warming (particularly the slow albedo feedback) is projected to go beyond that.
119329. michael sweet at 02:11 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        James Wright, It was pointed out earlier in the thread that this was a worst case analysis. The temperature change required depends on what you consider bad. If you are only worried about large areas of Earth being completely uninhabitable it requires 7C. On the other hand, CB Dunkerson at #5 pointed out that several thousand people have died already in heat waves throughout Europe. If climate sensitivity is really 6C per doubling (long term) we have currently committed the Earth to substantial warming. How bad does it have to be to be considered bad?
119330. Ned at 01:40 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        johnd, now you're talking about feedbacks, all of which apply to both the radiative forcing from CO2 and the (much smaller) forcing from waste heat. There's the water vapor feedback, the ice albedo feedback, the tundra/forest albedo feedback, etc. All of which will be very small for a very small forcing (waste heat) and much larger for a much larger forcing (absorption of IR by GHGs).
        Moderator Response: Indeed, the off topic of waste heat has been discussed enough on this thread. Further comments on that topic probably will be deleted from this thread. But please do suggest links to other treatments of that topic.
119331. e at 01:39 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        johnd, Talking about water vapour just confuses the question. You can compare the relative significance of waste heat vs. CO2 by measuring both of their effects on temperature without any feedbacks. Taking feedbacks into account just multiplies both sides of the equation by the same number. The rate vs. increase of a rate thing has been explained in pretty much every way possible. If it is still unclear, please try and re-read and see if one of the explanations sinks in. I don't think much more can be said on this thread.
119332. johnd at 01:14 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        If the heat sink for waste heat is water vapour, and water vapour concentration is relative to temperature, would not the increased water vapour due to that waste heat in effect accumulate the waste heat even if it is relatively small.
119333. Ned at 00:48 AM on 13 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        James Wight has a good point. Unfortunately, the table at global warming impacts doesn't really have a handy way of breaking down impacts as a function of temperature increase. That would be a long-term project -- it's basically what Mark Lynas does in his book Six Degrees. There's a handy version of this kind of chart in the IPCC AR4 SPM: Figure SPM.7. Examples of impacts associated with projected global average surface warming.  But it's entirely qualitative, unfortunately. I wonder if anyone ever tried to produce a similar graphic with quantitative metrics? That could get ugly fast, but it's an interesting information visualization challenge.
119334. Ned at 00:37 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP writes: "I understand the "theory"; however, there is no theory required to quantify waste heat. " There's no theory required to quantify the absorption of longwave radiation by CO2 either. You can measure it in the lab. Again, the complicated part is the feedbacks. You are verging onto "argument from incredulity". I really think you need to give this up. It's been explained over and over again (not just in this thread) that waste heat is quantitatively trivial compared to the radiative effects of greenhouse gases. At some point, continuing refusal to engage with the points that are made by so many other people crosses the boundary into trolling.
119335. Ned at 00:31 AM on 13 May 2010
        Earth's five mass extinction events
        Mike Roddy writes: Thanks for this, fascinating stuff, especially Chris #45. I have a question for nobody in particular: Hansen says that burning all the coal and tar sands will lead to Venus. BAU projections call for 5-7C temps in 2100, which is deadly, but not Venus. Does this mean that feedbacks at 5-7C will subsequenstly overwhelm the planet, since the rise in CO2 has been so rapid? Good questions. First of all, note that this is Hansen's own opinion, and other scientists may not be convinced by this claim. That said, Hansen is talking about burning all the conventional oil, coal, heavy oil/tar sands (cf Canada, Venezuela) and I think oil shale as well. That's a long-term, multi-century process, not something that would happen by 2100. So even if temperatures rise 5-7 C by 2100, Hansen's not saying that in itself would trigger a runaway greenhouse effect (RGHE?) like on Venus. What he IS saying is that if we spend the next few centuries burning everything, with CO2 over 1000 ppm, various other feedbacks like clathrates etc. would kick in and lead to RGHE conditions. That's still a pretty extreme claim, and I would want to see a bunch of convincing model results before accepting that it's possible. All that said, there's a lot of room for "extreme misery" even if we don't actually trigger a Venus-style RGHE. Burning a large enough fraction of coal and/or tar sands would put us at 3XCO2 and probably lead to disastrous conditions for much of the world's population.
119336. Stephen Baines at 00:17 AM on 13 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP It doesn't matter that it is more tangible. Imagine a bar for a waste heat forcing of 0.027 W/m2 on the forcing graph Doug Bostrom shows above. You would have a hard time even distinguishing it from 0. It's just not enough heat to matter much.
119337. Ned at 00:16 AM on 13 May 2010
        Earth's five mass extinction events
        The back-and-forth between batsvennson and chris in this thread might be a bit confusing for anyone who hasn't followed it closely. Back on the first page of comments, batsvennson wrote: [...] we may postulate a hypothesis that the current increasing of atmospheric CO2 concentration is a consequence of an current ongoing - for some reasons - (mass) extinction. This seems very peculiar to me. We know that we're adding CO2 to the atmosphere from combustion of fossil fuels, land use, and other factors. So the increase in CO2 in the atmosphere isn't a mystery. Batsvensson's hypothesis would necessitate some unknown mechanism removing anthropogenic CO2 from the atmosphere and some other unknown mechanism adding CO2 due to an ongoing mass extinction. (There is plenty of evidence that we are in the midst of a new mass extinction, caused by human impacts on the biosphere, but no evidence that this inherently is causing a large CO2 flux.) Occam's razor suggests that an explanation with zero unknown processes is preferable to one that requires two different unknown processes. So, Chris understandably points out (in this comment) that batsvensson's hypothesis is probably not a productive line of scientific inquiry: As for your "hypothesis"; why would we propose or consider a hypothesis for which there is not only zero evidence, but which is robustly contradicted by what we know of the real world? I don't see how it takes us anywhere scientifically speaking... batsvennson then asks Chris for more elaboration on these objections, and Chris obliges in this comment. There is some subsequent back-and-forth, ending with this very strange statement by batsvennson. Not all hypotheses are created equal. On the subject of the increasing CO2 concentration in the atmosphere, consider the following two hypotheses: H1: The increase is primarily due to combustion of fossil fuels. H2: The increase is primarily due to invisible leprechauns. I think most people would agree that the former is more productive than the latter, not just because it's more realistic but because it's testable. A hypothesis that is stated in vague, ill-defined terms, or that requires unknown and unexplained phenomena, is not really testable and thus is not particularly useful. Here's another case: H1: The increase is primarily due to combustion of fossil fuels. H3: The increase is due to the rapid deterioration of an undiscovered lens of frozen CO2 (dry ice) buried beneath the topsoil of a remote region of the Himalayan plateau. Now, unlike the leprechaun hypothesis, H3 is actually testable -- NSF or its European or Chinese equivalents could fund a field campaign to travel to Tibet and look for this interesting dry-ice feature. However, it's unlikely that a grant proposal focused on this hypothesis would be funded. Why? Because there's no prior evidence or reasoning to suggest that it's even remotely likely. A hypothesis with no justification for its own existence is better than an untestable hypothesis, but not much. Moving on, consider the next two hypotheses: H1: The increase is primarily due to combustion of fossil fuels. H4: The increase is primarily due to outgassing of CO2 from the oceans as they are warmed by a cyclical increase in solar irradiance. Now, H4 is clearly better than the leprechaun or dry-ice hypotheses -- it is testable, and it is at least based on plausible physics and some things we know about the relationship between temperature and the partial pressure of gases in seawater. But it still has problems -- in particular, it conflicts with other things we already know about the Earth system (solar irradiance has been decreasing, CO2 concentration in surface waters is increasing as CO2 moves from the atmosphere to the ocean rather than vice versa). In addition, H4 still requires some unknown explanation for why the CO2 that we know we're emitting from our cars and power plants is somehow not contributing to the atmospheric store of CO2. Now, batsvennson's hypothesis suffers from the problems of H3 and H4 above. She/he doesn't present any evidence to justify why we should even bother to consider "an ongoing mass extinction" as an explanation for the current rise in CO2, aside from one brief reference to a paper that suggests that some mass extinctions in the geologic past may have caused an increase in the CO2 flux from the biosphere to the atmosphere (but where's the evidence that's happening today?) More importantly, however, it is contradicted by the changing isotopic signature of atmospheric carbon. Finally, from a straightforward logical perspective it requires throwing out a much simpler explanation (we know we're producing CO2 from fossil fuels) in favor of a more complex one. As Carl Sagan said, extraordinary claims require extraordinary evidence. The claim that "something other than combustion of fossil fuels is responsible for the current rise in CO2" is most definitely an extraordinary claim. It's up to anyone proposing such a claim to provide extraordinarily convincing evidence. So far, batsvennson has provided no evidence at all.
119338. RSVP at 23:35 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        Ned "Likewise, when you add CO2 to the atmosphere, you're essentially creating lots of tiny machines that add X joules every year,.." Well put. I understand the "theory"; however, there is no theory required to quantify waste heat.
119339. James Wight at 23:14 PM on 12 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        I notice you’ve added this to the list of global warming impacts. I think it might be worth pointing out that some pretty extreme global warming (at least 7°C) is required for this to happen.
119340. Ned at 23:10 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        Oh, yes ... I forgot to add this: You write "The fact that [waste heat] is so easily calculated demonstrates how tangible it is." But it's much easier to calculate the heat added to the atmosphere from greenhouse gases than it is to figure out the total of all sources of waste heat! The complexity in predicting radiatively forced climate change is not in the initial heat transfer, it's in all the various feedbacks.
119341. Ned at 23:04 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP writes: Waste heat is perfectly tangible, unlike the indirect and complex effects of anthropogenic greenhouse gases. The fact that it is so easily calculated demonstrates how tangible it is. There's no difference -- heat is heat. Just in one case it starts out concentrated around chimneys, cars, etc. before dispersing, while in the other it's horizontally dispersed throughout the atmosphere right from the start. But the heat created by radiative transfer is every bit as real as the heat created by any other mechanism. If you insist on comparing CO2 to waste heat, you should think of the CO2 as equivalent to the machines that produce the waste heat, not the heat itself. If you add X joules of heat to the atmosphere, you increase the heat content of the atmosphere by X joules full stop. If you build a machine that adds X joules of heat to the atmosphere per year, then you've added X*L joules, where L is the lifespan of the machine in years. Likewise, when you add CO2 to the atmosphere, you're essentially creating lots of tiny machines that add X joules every year, and that will keep doing so for roughly a century or so. And every year we create more of these machines ...
119342. embb at 22:24 PM on 12 May 2010
        Are we too stupid?
        Jacob:What gives you the idea that reducing CO2 emissions makes a country's industry uncompetitive? Aren't we talking about an emission tax? It will increase the production costs hence make the industry less competitive. Jacob:OPEC is an excellent example of how powerful a coalition using reciprocity can be. If you think so... I seem to remeber lots of defections during its existence. Also, Russia, one of the biggest producers, is not a member. Are you sure this is the right model? Jacob:Neither I nor the EPA ever postulated that. Whatever gave you that idea? Simple: CO2 is a pollutant. People prefer to live in less polluted areas. Thus people should be willing to pay for having less CO2 in their area. Some element of this chain is faulty, which one is it? Jacob: You just dismiss that "The Lancet and University College London's Institute for Global Health issued a major report concluding that climate change is the "biggest global health threat of the 21st century."? No, I did not. You were talking about "immediate" effects, they are ttalking about "threats". Surely you see the difference. Jacob:Do you think geo-engineering is more or less risky than switching to sustainable energy? You completely miss my point. You were advocating immediate actions regardless of the risks. I am asking YOU if this is your attitude towards geo-engineering as well? Remeber? "So you argue for the preservation of the status quo because the proposed reforms may be imperfect? That is why I conclude that you have an interest in not mitigating climate change." If you argue against geo-engineering then according to YOUR own logic you have an interest in not mitigating climate change. That is all. Jacob:There is no police force in the case of the fig tree/fig wasp, is there? You might want to rethink this a bit. Evolution is about the survival of the fittest - so defectors will just die. If this is your example of a non-violent scenario you are really wrong. :)
119343. Zero132132 at 22:23 PM on 12 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        I haven't had time to look into it yet, so I must ask, does this study include the effects of increased temperatures on the amount of water vapor in the air? It would seem that both an increase in water vapor would drive the wet-bulb temperature, unless I'm misremembering something from genchem.
119344. RSVP at 22:13 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        chris Waste heat is perfectly tangible, unlike the indirect and complex effects of anthropogenic greenhouse gases. The fact that it is so easily calculated demonstrates how tangible it is. Waste heat goes directly into oceans and rivers (and the air) everyday, 24 hours a day. Power plants are water cooled for the most part, and the atmosphere does not get a chance to see this heat until it is exchanged at sea. Waste heat is real and accumulating, and yet somehow considered an inconvenient piece of data that is best ignored. I am not denying effects of GHGs, but it would be a useful exercise to assume a zero contribution of anthropogenic GHG (for the exercise) just to estimate how this alone would affect temperatures (assuming it is accumulating in some percentage). And in comparing to the actual average global temperature increase, this would help determine how much is actually due to anthropogenic GHGs. KR You comment that the higher the temperature, the more IR. I agree, but this applies to all forms of forcing, and is basically a form of negative feedback which maintains temperature convergence (to the benefit of all).
119345. Ned at 22:00 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        I agree with Dikran Marsupial that one can't draw conclusions about climate sensitivity by looking just at CO2 and temperature over the first half of the 20th century, since there were countervailing trends in other forcings. Here's a handy figure from Meehl et al 2004:
119346. Ned at 21:51 PM on 12 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        Arkadiusz Semczyszak writes: Thesis GW = greater frequency heat - it is already outside the mainstream of science. Not at all -- quite the opposite, in fact. The largest increase in temperatures is in winter and at night, but there's also an obvious trend of increasing intensity of extreme summer heat waves. Just looking at some recent papers, we find: Ballester et al. (2009): "... the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures ... 36% (B2) to 47% (A2) of future Central Europe July and August days at the end of the present century will be warmer than the 1961/1990 99th percentile." Beniston et al. (2007): "Heat waves – Regional surface warming causes the frequency, intensity and duration of heat waves to increase over Europe [...] The intensity of extreme temperatures increases more rapidly than the intensity of more moderate temperatures over the continental interior due to increases in temperature variability" Meehl and Tebaldi (2004) Clark et al. 2006: " [...] Although uncertainty associated with the magnitude of expected changes is large in places, it does not bring into question the sign or nature of the projected changes. Even with the most conservative simulations, hot extreme events are still expected to substantially increase in intensity, duration, and frequency. [...]" I'm not sure why you think that increasing frequency of heat waves is "outside the mainstream of science" when it's actually one of the most robust findings of both observational and modeling studies.
119347. CBDunkerson at 21:27 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        Dikran Marsupial #82, true. Looking only at CO2 oversimplifies the issue considerably. However, if you look at the chart doug provided in #71 you'll see that various other forcings (including solar) are comparatively minor and largely cancel each other out. If all the uncertainty bands came out with the highest possible result for each forcing that would just about equal the observed warming... but that isn't possible because parts of those uncertainty bands are from overlapping sources. For instance, we know that sulfate aerosols have a strong cooling effect, but we aren't sure how much of that is directly from the sulfates and how much is indirectly from compounds they form... so both forcings have large uncertainty bands, but they can't both be the highest (i.e. closest to zero) value. In short, the observed warming can't be explained even when we include all the known forcings... leaving unknown forcings or feedback effects to explain the difference. And we KNOW feedback effects are taking place because we can measure the change in albedo from ice retreat and the increase in water vapor from rising temperatures.
119348. Arkadiusz Semczyszak at 20:30 PM on 12 May 2010
        Heat stress: setting an upper limit on what we can adapt to
        #14 And even well-known popularizer of knowledge Ron Redfern in his book "Origins" (2000), writes that in the tropics during the last glaciation may have been even more tropical than at present (significant reduction - compression THC) and the Northern Siberia, formed stable - static for thousands of years - Anti-cyclones. Strong warming is perhaps the disappearance of cyclones - almost pressure gradient = 0? In summer, temperatures in Siberia could be as high as above 45 deg C ... Sherwood'a work is very valuable and interesting but not very useful for prediction of ways to adapt to GW. Thesis GW = greater frequency heat - it is already outside the mainstream of science.
119349. chris at 19:58 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        RSVP at 18:58 PM on 12 May, 2010 RSVP, doug has already corrected for a spherical Earth, angle of incidence, albedo. The TOA average solar radiation is 1,366 W.m-2. If you divide by 4 to account for a spherical Earth, and multiply by 0.7 - 0.8 to account for the Earth's albedo, the surface solar radiation is around 250 W.m-2 averaged over the Earth's surface. Please stop these tedious attempts to pursue false arguments based on ignorance. You've been here long enough to have learned some basic backround information on these subjects. The idea that a straightforwad subject like the contribution of waste heat to the Earth's energy balance has to be gnawed over by a boring recapitulation of the whole theory and empirical knowledge of radiative forcing and energy balance, as if the subject has only just been awakened and needs to be sorted out fom scratch on this thread is tedious in the extreme. Several useful sources of info on this have been posted aready on this thread - please go and read them...
119350. RSVP at 18:58 PM on 12 May 2010
        Estimating climate sensitivity from 3 million years ago
        doug_bostrom "surface of the Earth is about 510,000,000 km2. So, about 127,500TW of total insolation" You are taking the total surface area. Only one side of the Earth gets Sun at any given time, so you will need to at least half that result for starters and reduce some more to account for albedo. In any case, the absolute amount of insolation is supposedly a non-issue (neither here nor there) for those that base their analysis on the radiative forcing model (the tree graph that has branches going left and right). Its funny how the total solar insolation is never mentioned in that context, only when the question of waste heat is brought up.

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