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johnd at 06:33 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
e at 05:55 AM, re "As the level of CO2 in our atmosphere rises, the rate at which heat dissipates into space continues to go down." That rate is not directly because of the CO2, but because of the water vapour which responds directly to temperature, and also absorbs and transmits IR radiation over a much wider band than CO2 or any other greenhouse gas. If CO2 has been calculated as having a long residency time, what is the residency time of water vapour. 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. -
KR at 06:32 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
RSVP, you bring up thermal emissions and their contributions to global temperatures; keep in mind that GHG's change the steady state condition of the Earth's temps, not just the current temps. If the Earth's temp rises above steady state values, it will lose more energy to space (long wave IR energy) than we gain from the sun, and the temps will drop. Industrial thermal energy is not cumulative over the long term. In fact, if industrial heat contributions were the main cause of global warming, the energy imbalance at the top of the atmosphere would be positive - more energy coming from the earth than it receives, as the Earth tried to return to a steady state condition. That's NOT the case: A negative imbalance indicates energy trapping, not energy production, and that should invalidate the industrial energy->global warming hypothesis. -
Tom Dayton at 06:23 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
The waste heat argument is not really on topic for this post. John does not have an "Argument" post for waste heat, but he does have a set of links for it, with at least one good article linked there. I think everybody should stop commenting about that topic here, but should pitch in by suggesting additions to that Links page if you've got relevant material. -
NewYorkJ at 06:12 AM on 12 May 2010Climate Change and the Integrity of Science: a letter to Science
As others have pointed out, the NAS consists of a very broad set of individuals, many with little knowledge or experience with climate science. So it's not a surprise that the letter seeks support from those with the strongest knowledge. They might look for more broad support for statements like this: "We also call for an end to McCarthy-like threats of criminal prosecution against our colleagues based on innuendo and guilt by association, the harassment of scientists by politicians seeking distractions to avoid taking action, and the outright lies being spread about them." One doesn't need a great depth of climate science expertise to support a statement like this. I would think that nearly every NAS member would support this or a very similar statement (although the harassment is not limited to politicians). The attacks on scientists is utterly disgraceful. On the other hand, many scientists are quite cautious about getting involved in anything that seems the least bit political. They do the research and let the science do the talking. -
Doug Bostrom at 06:08 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
RSVP, if you do some quick calculations you'll see that waste heat (I assume you're speaking of "cultural heat", heat from nuclear and chemical sources liberated by human activities) is remarkably small compared to heat from insolation, so small that it essentially disappears compared to insolation 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. As a basis of comparison, the present total electrical generation capacity of our global attempt at civilization is about 16TW. -
Estimating climate sensitivity from 3 million years ago
RSVP, I don't think you are understanding Chris's point. As temperatures rise, the rate that heat dissipates into space also rises, until the rate of warming and the rate of dissipation equalize, and the climate is in equilibrium. As long as the rate of warming influences remains constant, there is no accumulation of heat. The problem with CO2 is it takes thousands of years for feedback mechanisms to balance out and remove CO2 to a significant extent. As a result, even if our CO2 emissions stabilized at the current annual level, CO2 would still accumulate in the atmosphere. As the level of CO2 in our atmosphere rises, the rate at which heat dissipates into space continues to go down. This has the effect of pushing the climate's equilibrium temperature ever higher. In contrast, if we could freeze the rate of waste heat at current levels, it would no longer have a continued effect on our climate's equilibrium level. The point is not that waste heat should be ignored, it's that its contribution is minor compared to that of CO2 emissions. In any case, reducing our reliance on fossil fuels would mitigate both issues. -
RSVP at 04:47 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
Chris Why go back only 100 years? 100 years or pre-Industrial Revolution is pretty much the baseline condition for the detected changes in CO2 ppm and average global temperature. This is what AGW is focussed on I believe. A "modern" event. What happened before this is irrelevant. Natural cooling may have absorbed/cancelled any significant anthropogenic contributions 20 times in the past for all we know. For the point I was making, I assume that the natural fluctuation is completely stable over the last 100 years. The only two things to consider then is effects of greenhouse gases and waste heat. But you cant ignore a cummulative effect of waste heat while at the same time holding everything else constant (and even worse, assuming that the IR lid is even tighter). So some of the warming must be attributed to waste heat. The other detail is that you have what is called winter and night. Either global warming is only associated with warmer days and warmer summers, or the heat is accumulating somewhere (and that somewhere is our oceans). -
JMurphy at 04:22 AM on 12 May 2010Kung-fu Climate
Likewise...although I doubt whether I initially posted anything more relevant ! As a final, final comment from me here (and I mean it this time), I want to congratulate this site, John Cook, all the article authors and most of the contributors for laying out all the arguments and answering all the skeptical queries (as far as I have seen, anyway). I learn something new every day on this site so I'm sorry to have been a part of dragging this thread into such a pointless and circular argument - especially as that is exactly what the so-called skeptics want. -
Alexandre at 03:56 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
Maybe an interesting further step would be comparing map B with the map of future scenarios likethis one:
Southeastern Asia seems to be already close to the edge, and the few extra degrees of projected warming could make it exceed the tolerable limit. South America and sub-saharian Africa also seem vulnerable.
Let´s also keep in mind that this map here is the temperature anomaly for the period 2070-2100 (scenarios A2 and B2). Temperature does not stabilize there, though. Warming is expected to continue in the coming centuries.
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TOP at 03:52 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
I remember traveling in the Gangetic plain when it was 120F. It was nice. No mosquittoes or flies. They all died so we didn't have to use a net to sleep. Hot day and night. Just keep a watermelon handy. One little appreciated fact is that the global dew point is rising 3x faster than the global temperature. When the two meet the problem is solved. -
Ned at 03:48 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
HR, let me turn around your implied question: why do you think so many "skeptical" papers about climate sensitivity have turned out to have serious flaws? I take it you don't dispute Schwartz's own revisions to his original paper, and I assume you're likewise willing to accept that the problems with Chylek (see here and here) are real. Everybody including Roy Spencer seems to agree that there were significant problems with Lindzen and Choi. I would assume that the reason for this "pattern" is presumably that climate sensitivity really is somewhere around 3C, so papers that find much lower values understandably must have flaws or they wouldn't have found such an anomalously low value. Do you have a different explanation to suggest? Or another question: are there high-quality papers published in the peer-reviewed literature in the past decade that you would point to as convincing and that give a climate sensitivity below 2? I'm not aware of them, but maybe I'm missing something. -
Ari Jokimäki at 03:22 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
The "pattern" arises quite naturally, I think. Whenever there's some value being measured, one wishes to explain the outliers. Therefore the studies reporting values outside the regular range are more likely to be checked more thoroughly than the papers giving values within the regular range. It doesn't mean that the papers within range are not checked at all, it just means that papers outside the range are checked more thoroughly to find out why they find such strange values. As we have seen here, there are lot of papers that have determined the value of climate sensitivity. In that kind of situation there's not much chance that couple of outliers would be correct (and dozens of others would be wrong), so it's not surprising that we keep finding errors among them. -
Doug Bostrom at 03:00 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
I found this paper very interesting in the way it establishes a fairly uncontroversial boundary or limit of "adaptability" to global warming. Retreating from areas of the globe where we evolved is adaptation, sure, but could hardly be termed a success story. As Ned mentions this won't be a smooth process. Given less extreme conditions than those hypothesized in the paper we'll nonetheless witness unacceptable excursions, presumably with those excursions becoming more frequent and obvious the closer we actually do approach the extreme case. Time to begin breeding dogs with longer tongues... -
chris at 02:38 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
HumanityRules at 01:53 AM on 12 May, 2010 HR, Schwartz's paper has got nothing to do with volcanos [*]. So the point you are making is pointless. In any case Schwartz himself recognised that his analysis was flawed, and wrote a retraction in which his reanalysis brought his estimated climate sensitivity back into the IPCC range. Are you suggesting that we should continue to include his original analysis in our summary of the science on climate sensitivity even though Schwartz himself says it's incorrect? That would be taking efforts to misrepresent the science to truly heroic proportions! As for the 2007 IPCC report. It's rather unlikely that a 2007 IPCC report would include very much of the scientific literature from nearly 20 years previously. This early literature will have been consolidated in reviews, and in any case the role of the IPPC's periodic reports is to bring the state of knowledge of relevant science up to date. The Shaviv and Veizer (2003) paper is probably unlikely to have been cited by the IPCC ('though it might have been - why not have a thorough look?). It's really a hypothesis (note the title: "Celestial driver of Phanerozoic climate?" - incidentally the answer is almost certainly no!) and was published in the GSA house journal GSA Today which isn't considered part of the scientific literature (it's not indexed by ISI for example); that's not to say it isn't an excellent magazine btw, nor that the Shaviv Veizer hypothesis wasn't interesting). In any case Veizer subsequently reanalyzed his paleotemperature data, and the hypothesis pretty much fell flat. As for your "struggles with patterns forming", it's difficult to konw what to say. Of course if we're interested in the science then we're really interested in the evidence, and perhaps your struggles involve a difficulty getting to grips with that. It would help perhaps if you were to look at the papers you refer to... ------------------------------------------- [*] He estimates heat capacity response of the oceans from an analysis of ocean heat uptake, and he estimates a time constant for heat uptake by autocorrelation of the heat capacity during 1880-2004. How can you comment on this paper if you don't know what it's about? -
CBDunkerson at 02:26 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
RSVP #55, setting aside the incorrect atmospheric CO2 figures... your math is also off. The statement that a doubling of CO2 without feedbacks causes a 1 C increase in temperatures can be mathematically expressed as; X * ln(2Y/Y) = 1 C Where X is a constant and Y is the starting CO2 level. Plugging in your values we get ln(380/250)=0.41871. The natural log of 2 (from a doubling, 2Y/Y) is 0.693147. If 0.693147 X = 1 C then 0.41871 X = 0.6 C, not the 0.76 C value you came up with. Using the actual CO2 figures for today vs 100 years ago gives ln(387/300)=0.367371 C warming... as opposed to the ~0.7 C actually observed. Ergo, we have observed more warming than can be explained by the enhanced CO2 greenhouse effect. Thus demonstrating that total feedback effects over the past hundred years have been positive. Not to mention consistent with both models and reconstructions of past climate change. -
Geo Guy at 02:21 AM on 12 May 2010Climate Change and the Integrity of Science: a letter to Science
Stephen Baines - 219 My numbers were for the US only, hence the reference to the EPA so I stand by them. With respect to CO2 being heavier than air, it does tend to fall and collect near the earth's surface - sometimes in great quantities. Volcanists are very aware of this danger when undertaking field studies. Then there is the high concentration of CO2 near Mammoth California that were so concentrated it killed trees. pubs.usgs.gov/fs/fs172-96/ Over time I contend that SO2 does have a greater effect on ocean acidity simply because the acid lakes and rivers eventually make their way to the ocean where currents distribute the waters with low pH around the oceans. As for residence time, I disagree as a gas with a lower specific gravity and lower solubility in rain water will stay in the air longer than one with a much higher solubility and a specific gravity that is 50% higher.. robhon # 218 - personally I am at a disagreement with the work done by the IPCC - for a number of reasons which probably should not be posted here as it would be deemed to be off topic. Suffice to say I have investigated the resolutions by the UN that created the organization and from that point on I've seen enough to be dissuaded by their work. scaddenp # 214 - while there are models used to predict ENSO events, my reference was to the global climate models and the integration of the forecast of ENSO events into the climate models. To be properly treated, they should be an input parameter and not an output - of course if they did that, then their models would appear to be out of whack. IF the ENSO events are a result of high levels of CO@, then I agree they would be an output. But since we do not know the origins of them (what causes the features that create the warming and cooling trends) we must conclude that their cause is something other than CO2 and hence they should be an input item -
Dikran Marsupial at 02:00 AM on 12 May 2010Kung-fu Climate
Likewise :o( -
HumanityRules at 01:53 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
#51 Chris Thanks for pointing those out. It's not straightforward but I had a look see if any made the cut in the 2007 IPCC report. Couldn't find them. Shaviv and Veizer (2003) Washington and Meehl (1989) Mitchell and Ingram (1989) Gillard and Schneier (1984) Idso (1980) More generally I struggle with a pattern that is forming in which any paper that estimates low sensitivity has huge flaws in it while those with estimates around the IPCC range are uncritically accepted. As an example in John's previous list Schwartz is critisised partly on the basis that it uses volcano's which may have different features to other forcings. Yet this is not raised earlier in the list for the Bender 2010 paper (which just happens to have a more acceptable value). It also didn't stop the IPCC from referencing other papers on volcano's or including a whole section on it. http://www.skepticalscience.com/climate-sensitivity.htm http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-6-2-2.html -
Miriam O'Brien (Sou) at 01:45 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
The difficulty with air conditioning is that most household air conditioners are only rated up to about 41C, some to 43C I think. When the temperature rises to 51C for any length of time, like a summer heat wave, we'll either have to invent better air conditioners and de-humidifiers or find another way to keep cool. (That's only 4C warmer than it got to in the heat wave in Melbourne in southern Australia last year - and the global temperature is still climbing.) Maybe building underground like at Coober Pedy will help. -
J Bowers at 01:36 AM on 12 May 2010Kung-fu Climate
Apologies for getting involved in the ding-dong, especially as I initially posted something far more relevant. -
chris at 01:28 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
RSVP at 00:19 AM on 12 May, 2010 Not really RSVP. Your analogy isn't a meaningful one in context. Here's an appropriate analogy. You live in one room shack in the woods. Your shack is cold (it's the same as ambient temperature) and therefore you light a fire in the fireplace and arrange that this provides a constant thermal output (the equivalent of human "waste heat"). The temperature of the shack rises a bit and stabilises at a temperature whereby heat from the fire is balanced by loss of heat to the outside. Note that although "energy cannot be destroyed", it isn't accumulating in the shack. The temperature doesn't keep on rising! The energy is dissipated to the outside. You decide that you find the situation still uncomfortably cold. You therefore put a layer of insulation on the outside walls (the equivalent of enhancing the greenhouse gas concentration in the atmosphere). The dissipation of thermal energy to the outside is less efficient and the temperature inside your shack rises until a new equilibrium temperature is reached. Since you quite like the effect you keep on adding to the insulation. Each time the added insulation provides an additional increment of prevention of heat loss and the temperature continues to rise. etc. etc. Note btw that if you were to take your scenario to its logical limit then the accumulation of heat in the Earth system would be unbearable. Why go back only 100 years? If energy was "accumulating" then the preceding millenia of forest fires, heat from volcanic eruptions etc would have turned the planet into fiery hell. Happily, the Earth is in radiative balance with its surrounds (at least it tries to be!), and forcings don't result in the continual accumulation of thermal energy; they result in the movement of the Earth system to a new equilibrium state. The equilibrium state resulting from human "waste heat" is a tiny fraction of a degree above the Earth surface temperature that would exist without it.... ...incidentally, 100 years ago the atmospheric [CO2] was ~ 300 ppm (not 250 ppm). So you need to recheck your maths... -
mike roddy at 01:27 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
It's going to be worse than what these studies indicate. I spent a lot of time in Delhi about 10 years ago, which falls within the pale red zone, due to local humidity. 45C was common, and people were barely able to deal with it. If there was a heat wave, people slept on roofs and sidewalks at night, and avoided exercise in the day. I don't think that we have much experience with 48C in a humid climate with few breezes, as in north central India. Mortality is likely to be very high, and there will be more emigrants than from Bangladesh, which has a smaller population that can more easily move to higher ground. The Himalayan foothills are already heavily populated and deforested. I've also lived in 50C weather, in the Southern California inland desert, which may be the hottest region on earth by temperature. Delhi was much worse, and the area is obviously far more populated. I'm glad you're bringing this up, John- this problem is quite overlooked, since it's simpler to talk about rising tides. -
MarkR at 01:18 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
Wow, that's something I'd never considered before! I'll certainly look it up. @Arkadiusz: interesting point. In the Cretaceous it appears there was a weird equator-pole temperature gradient. Perhaps new mechanisms (increased cyclone activity to redistribute heat perhaps?) could counter some of the dangers raised in this paper. I must read more! @factfinder: you're making the common mistake of confusing weather and climate. John did a little article on this. Currently we're going through (globally) the second warmest 12 month period ever recorded, according to satellites, despite a record solar minimum. Europe and the US have been reasonably cool though, for various reasons (winter was thanks to the Arctic Oscillation, f'r'instance). -
Ron Crouch at 00:58 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
From Thermoregulation Quote: "The lower limit of temperature that humans can endure depends on many factors, but no one can survive a temperature of 45 °C (113 °F) or above for very long. Mammalian muscle becomes rigid with heat rigor at about 50°C, with the sudden rigidity of the whole body rendering life impossible." So remember that the temperature inside your car can easily climb over 50C even with the windows cracked. Guess what happens to Fido. Heat stress for production animals generally diminishes in 24C (75F) and above conditions depending on the animal involved, with onset generally in the 24C to 28C range. There are lots of data on the net to support this. Obviously then the amount of land area that would become uninhabitable through dry bulb temperatures exceeding ~44C would also increase. -
RSVP at 00:19 AM on 12 May 2010Estimating climate sensitivity from 3 million years ago
"If the amount of CO2 in the atmosphere is doubled, the change in global temperature without feedbacks would be around 1°C." For the last 100 years, CO2 has gone roughly from 250 ppm to 380 ppm, a ratio of 1.52:1. If the above is true, global warming should be around 1.52 / 2 = 0.76 C. Since climate models assume the Earth's temperature holds within a strict equilibrium, the effect of every extra exothermic calory released since the beginning of the Industrial Revolution should (to some degree) be having a cumulative effect. How can this not be accounted for, especially by those who maintain that with more CO2, the ability of the Earth to discharge heat has diminished? The "non skeptic" replies to this question typically indicate that this waste heat is comparably small, however the value provided is only given for one year as opposed to 100 or 200 years. A balance scale analogy may be helpful. If 100 kilos are hung across a balance scale, and then a dash salt is added from a salt shaker on one side, a significant movement is not expected; however, if a dash of salt is added everyday for 200 years, eventually the scale will tip. As energy cannot be destroyed, it must be accumulating. I think the phrase, "you cant have it both ways" applies, such that if the Earth's thermal balance is so delicate, one cannot ignore the effects of human waste heat, and that some significant part of heating is not coming from CO2. In either case, it is coming from the use of non renewable energy sources. -
ianw01 at 00:12 AM on 12 May 2010Heat stress: setting an upper limit on what we can adapt to
The sharp cutoff of the red Tw plot deserves further explanation. Clearly there is a phenomenon that causes the upper cutoff despite the higher temperature (black) and max temperature (blue) curves. Until the Tw curve is explained, it does not necessarily follow that the Tw curve will shift right as temperatures rise. One would think it should rise, but one would not expect that sharp upper cutoff. -
Arkadiusz Semczyszak at 23:51 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
It should be noted that the warming of 6 degrees C (and more), an increase of temperature (mostly) in the cold season. In tropical regions, such as during eemian, could be even colder than it is now ... Theory of a tropical thermostat - confirms it: no adjustment to temperature changes in the coral, similar areas inhabited by gorillas (Africa), etc.. It is also worth noting that even evolutionarily oldest tropical plants are not adapted to higher temperatures than at present. Meanwhile - in cold zones: e.g. Dr Jim Provan, from Queen's School of Biological Sciences, describes in his works a huge potential adaptation (for warm) of algae in the Arctic. Cod tolerate swings in temperature + / - 8 degrees C ... In ancient times the warm (6-12 ° C more than today), underwent extension in the temperate zone of marine version (6-8 degrees), or tropical mild (> 7-9 degrees) - for nearly the entire globe. Do not threaten us, then year-round heat. For example, heat waves in Europe (2003, 2006), only effects of violent La Nina - CLAW hypothesis - not GW. -
John Russell at 23:32 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Thanks, John. I've learnt something. Having also been in tropical rain forest in extremely high humidities I'd assumed that I'd also been in equally high temperatures in those conditions; but I guess I haven't or I wouldn't be here to tell the tale.Response: Damn, you've had an interesting life, John. Working from home, it's a good day for me if I manage to get out of the house. -
Jacob Bock Axelsen at 22:11 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Other sideeffects of global warming includes asthma and allergies from pollen and fungii, malaria/West Nile virus/dengue fever from spreading mosquitoes, tick borne Lyme disease and perhaps a 30% increase in kidney stones from dehydration. Coming global warming could even be the greatest health problem according to experts. Take a minute to contemplate just how radical a statement that really is when it comes from false positive averse experts. -
Ned at 22:01 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
CBDunkerson writes: Thus, long before any portion of the Earth would reach the point of regularly experiencing lethal conditions we are going to see large portions of the globe being hit by them every few decades. This is a very important point. When thinking about the economic and biological impacts of climate change, it's essential to look at the variance, not just the mean. Obviously, it would be disastrous if the global mean temperature increased to the point where Tw exceeded 35C in Texas, Senegal, and New South Wales every year. But it would still be disastrous if temperatures only increased to the point where that happened during the one-sigma heat waves a couple of times per decade, or even the two-sigma heat waves every twenty years or so. -
quokka at 21:51 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Berényi Péter: If you go to the "4 Degrees and Beyond" conference presentations download page: http://www.eci.ox.ac.uk/4degrees/programme.php and download Dr Richard Betts presentation on regional climate change, there are a number of global maps showing model projections for regional temperature anomalies for various warming scenarios. The map for a global anomaly of 5.4C is truly frightening in it's regional implications. 4C is bad enough. -
Ned at 21:50 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Berényi Péter, that raised a red flag for me when I first read this paper. However, they are very clear in the introduction that this is (a) a worst-case scenario, and (b) a projection beyond the traditional horizon of 2100. If you assume that climate sensitivity is in the upper 5% of the accepted range, that no serious mitigation measures are undertaken, and that population growth and industrialization of developing countries results in the consumption of a larger fraction of coal reserves over the next 200 years, a mean temperature increase of 10C or more is possible (more at NH high latitudes, less in the tropics). I think James Annan would probably dispute this approach. Personally I'd like to see any discussion of this paper clearly emphasize that it's based on a "worse" (perhaps not "worst") case scenario rather than on the most probable scenario. On the other hand, given the chance of seriously intolerable outcomes for much of the world, I do think it's necessary to consider less-likely but possible negative scenarios. IPCC's forecasts have turned out to be too cautious in some cases, after all. In any case, Sherwood and Huber 2010 explain this quite clearly in their first paragraph, with references. Have you looked at the paper yet? -
Ari Jokimäki at 21:41 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
HumanityRules (#48) wrote: "Is there any justification for putting one year memory rather than leaving it out?" Yes. In an earlier study Lin et al. found that the climate memory is at least 8 years, so putting in a short memory instead of no memory is better. But of course, when you are dealing with the real life you need to use a memory > 8 years. -
CBDunkerson at 21:38 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
We already see this effect in current weather cycles. The European heat wave of 2003 killed tens of thousands of people. Another in Europe and the US in 2006 killed a few thousand. Then again in 2007 a few thousand more in Asia. That is all weather, but in a warming climate the weather conditions for high temperature and humidity occur more frequently. Thus, long before any portion of the Earth would reach the point of regularly experiencing lethal conditions we are going to see large portions of the globe being hit by them every few decades. It would be interesting to see what Tw was in decades prior to 1999 or by year rather than decade. If it has been creeping up, as seems likely given the increase in temperatures (and thus perforce also humidity), then it represents a measurable 'fatality index' to global warming which could be correlated against heat wave deaths. -
chris at 21:36 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
A somewhat related paper was published not long ago also in Nature Geophysics which also indicates the possibility of very significant longer term amplification of greenhouse-gas induced temperatue rises via poorly understood mechanisms. Obviously we are aware of the possibility for what might be considered catastrophic non-linear consequences of warming (rapid collapse of polar ice sheets; massive release of methane from hydrates etc.). Unfortunately it's not straightforward to factor these into the analyses of mitigation and adaptation policies. R. E. Zeebe et al. (2009)Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming Nature Geoscience 2, 576 - 580. -
Ned at 21:29 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
Chris, I agree 100%. The last thing the IPCC (or anyone) should be doing is classifying papers into "skeptic papers" and "pro-AGW papers" and then for the sake of evenhandedness being sure to cite three from column A and three from column B. There have been lots of good studies of climate sensitivity. Some find higher values (Lunt 2010, Hansen) while others find lower (James Annan). IPCC should and does consider the range of findings among strong, well-conducted studies in the literature. On the other hand, there are also papers about climate sensitivity that have serious flaws (Chylek here and here, or Lindzen & Choi here). I don't think IPCC should overlook those flaws and give them unwarranted consideration for the sake of offering "equal time" to all sides. The only distinctions that should matter are whether a paper is insightful, robust in its methods, justifies its conclusions, and leads to further productive research. -
Berényi Péter at 21:23 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Would someone explain how temperature at (sub)tropics could increase by as much as 7 °C and more? -
chris at 21:18 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
HumanityRules at 17:48 PM on 11 May, 2010"Your list doesn't seem to include any of the so-called sceptics papers?"
Actually I've just had a look at Ari Jokimäki's list. Of course it depends on what you mean by "so-called sceptics papers", but if you mean papers by individuals that arrive at low climate sensitivity by hopelessly flawed analysis, or more generally any paper that infers a cimate sensitivity below the likely IPCC range (e.g. below 2 oC of equilibrium surface warming per doubling of atmospheric [CO2]), then the list has lots of "so called skeptics papers". e.g. referring to my brief list in post 49 above, Ari has: Chylek and Lohmann (2008) Schwarz (2007) Shaviv and Veizer (2003) and there is also: Washington and Meehl (1989) Mitchell and Ingram (1989) Gillard and Schneier (1984) (Idso (1980) -
Riccardo at 20:53 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
It's interesting to notice that the body temperature of mammals, including us humans, falls within a relatively narrow range. We all share the need to dissipate heat and the "last resort" of perspiration. So we also share roughly the same wet-bulb temperature limit. This limit can be found in any introductory physics textbook for biomedical sciences but this is the first time I see it applied to humans in their environment on a global scale. Great. -
Ed Davies at 20:13 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
Any thoughts on heat-stress effects on animals, domesticated and wild? Even vegetarians need animals in many tropical areas for ploughing and transport.Response: Good point, I forgot to include that they do mention mammals in their study. One of their concluding paragraphs reads (emphasis mine):In principle humans can devise protections against the unprecedented heat such as much wider adoption of air conditioning. But the power requirements of air conditioning would soar; it would surely remain unaffordable for billions in the third world and for protection of most livestock; it would not help the biosphere or protect outside workers; it would regularly imprison people in their homes; and power failures would become lifethreatening. Thus it seems improbable that such protections would be satisfying, affordable, and effective for most of humanity.
They also mention earlier that "Any exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible." So obviously heat stress will have a significant impact on livestock which will affect food supply. -
John Russell at 19:59 PM on 11 May 2010Heat stress: setting an upper limit on what we can adapt to
When working in the Kalahari desert in Namibia I've been in temperatures of 45 degrees C for periods of an hour or two. It's extremely uncomfortable, even in the shade. At same time as I've been in discomfort with a camera on my shoulder, wearing shorts and a light cotton shirt, I've been filming locals transplanting, weeding or harvesting crops who are wearing dark trousers, shirts and loose dark-coloured jackets -- some even with woollen hats. I guess I learned that, provided there is a supply of clean fresh water, humans can hang on almost anywhere -- speaking geographically -- though I doubt whether it'll be me or thee. This comment should in no way be taken to mean that I don't think that efforts to avoid climate change should not be of the highest priority.Response: The wet-bulb temperature is different to air temperature. In a desert environment, the wet-bulb temperature is lower due to the low humidity. This is why desert areas show the same wet-bulb temperature as more humid tropical regions. -
chris at 18:44 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
HumanityRules at 17:48 PM on 11 May, 2010 on your:"It would be worrying if the IPCC were to do the same. Having divided off a group of scientists, labelled them denier, questioned their motives it then seems possible to behave as if they don't exist."
That's silly HR. The IPCC consider all scientifically valid research. The authors consider the topic of their particular remit in its entirety, assessing all the published literature and other relevant data sources. So they will know aboput your so-called "skeptic papers" and these are considered on their merits in line with the available science. So if a paper is shown to be incorrect, this may not be mentioned, or more likely will be discussed in terms of the data that denonstrate its flaws (since bad science does have its uses). Your notion of "skeptic papers" is a curious one. As far as I can see there are only papers. Anything that is published in a scientific journal is a scientific paper, and having got there it lives or dies according to the interest it generates, the criticisms it generates and so on. The notion that there is some sort of alternative "science" of "skeptic papers" is a dodgy one to me. Of course there are a tiny amount of knowingly scientifically invalid papers that are winkled into the scientific literature (of the thousands of papers on climate science published a year, there might be 3 or 4 of these; they're often the ones we hear about!). But if that's what you mean by "skeptic papers" why would the IPCC or any scientific body or group consider these when assessing the state of a scientific field??? Your second sentence in the quote from your post is breathtakingly hypocritical! Clearly some rather scurrilous groups are attempting to do what you suggest (witness the pathetic and rather disgraceful attacks on Professors Mann and Jones). You can see by reading some of Poptech's post the way in which some people use these attacks as a means of attempting to disregard (in the manner you suggest) anything from the sources (e.g. Poptech on the CRU temperature data). But in fact the situation from the scientific side is straightforward. Spencer and Braswell, and Chylek, and Schwartz, and Lindzen and Choi were published (flaws notwithstanding). The reason that we reject these papers as valid contributions to our knowledge is that they hve been objectively shown to be flawed. mostly by extensive critique in the form of publications by others. It's certainly not because we reject them out of hand. Obviously we are likely to be a little suspicious of papers from certain sources but that's the price paid by those that attempt to sneak bad science into the scientific literature! -
chris at 18:27 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
Which "skeptic" papers HumanityRules? Lindzen and Choi has been objectively shown to be incorrect. They cherrypicked their timepoints, and made incorrect assumptions that are fatal to their interpretations. Schwarz's paper on climate sensitivity using a simple model of ocean heat capacitance and "guessed" response times was shown to be objectively incorrect. He recognized this and published a correction which now shows that in his model the apparent climate sensitivity isn't below the IPCC range anymore. Chylek's paper on the estimation of low climate sensitivity from examination of temperatures and atmospheric reflectance during ice age transitions was shown to be objectively incorrect. Like Lindzen and Choi, Chylek et al made non-objective selection of time points. Similar flaws effectively sink papers on climate sensitivity by Spencer and Braswell, and by Shaviv. etc. etc. Why would one include papers that are objectively wrong in a list of papers that inform us about earth climate sensitivity? If we want to understand phenomena in the real world we reject analyses that have been demonstrated to be incorrect. which papers did you consider should be on your list? -
HumanityRules at 17:48 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
45.Ari Jokimäki Is there any justification for putting one year memory rather than leaving it out? Your list doesn't seem to include any of the so-called sceptics papers? It would be worrying if the IPCC were to do the same. Having divided off a group of scientists, labelled them denier, questioned their motives it then seems possible to behave as if they don't exist. -
Riccardo at 17:37 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
Berényi Péter, there's no formal definition of slow or fast feedbacks, they must be considered relative to the time scale analyzed. -
Berényi Péter at 17:07 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
What are the timescales involved? I understand slow feedbacks are supposed to operate on timescales from hundreds to thousands of years. But how fast are fast feedbacks? Days? Weeks? Years? Decades? -
tobyjoyce at 16:46 PM on 11 May 2010Climate Change and the Integrity of Science: a letter to Science
@johnd #216 I am disappointed you could not substantiate your assertions, which I will now ignore completely as a rhetorical overstatement, and without real foundation. It seems to me that you should be one doing the research. You could start by reading the thread on climate sensitivity at this blog. The thread lists links to 12 papers on climate sensitivity. In none of them do the authors confess "doubts", other the wish to refine their analyses. Climate Sensitivity -
Ari Jokimäki at 16:24 PM on 11 May 2010Estimating climate sensitivity from 3 million years ago
Recently a paper was published that addressed Spencer's feedback studies, I wrote a brief piece about it. The paper addresses the Lindzen stuff also, but there's not much hope for Lindzen anyway, and I don't think there ever was. If people are keen to look for lot of climate sensitivity papers, here's a list of some of them. -
Phila at 15:17 PM on 11 May 2010Climate Change and the Integrity of Science: a letter to Science
#212 "it wasn't to provide any proof but rather simply to show that climate varies widely" Why does this need to be shown? Is there anyone on this site who doesn't know that climate varies widely? Or that it's complex? In my experience, people who accept AGW know this already. More to the point, they understand that complexity and uncertainty can lead to understating risk, as well as overstating it. -
Stephen Baines at 15:07 PM on 11 May 2010Climate Change and the Integrity of Science: a letter to Science
Geo Guy #216 Good, we can agree that atmospheric SO2 is largely produced by man (actually about 90%). That's a start. Your comparison of CO2 and SO2 emissions are WAY off, though (really, you need to check your units!) In 2004 CO2 emissions were 38 GIGATONS (AR4 IPPC). More than 30% of that entered the ocean - or conservatively about 12-13 Gt. Global SO2 emissions even at the peak of emissions in the 1990 were only about 154 million tons (or 0.154 Gt) according to the World Resources Institute – much more than you claimed but a lot less than CO2 emissions. Less than half of SO2 emissions get to the ocean (36-51 % according to Dentener et al (2006)) because it rains out so quickly. Most estimates I have seen suggest more like 30-40% - not that different from CO2. So basically ratio of SO2:CO2 entering the ocean is similar to SO2 and CO2 emissions, about 1:1000. But buffer chemistry is complex, right? And there are other strong acids in human emissions. What of them? There was a paper in Proceedings of the National Academy of Sciences (Doney et al 2007) that directly addressed the effect of sulfur and nitrogen deposition on ocean acidity and found that it amounted to only a few percent of the effect of CO2 over the whole ocean. Locally, near the coasts, acidic N and S deposition could contribute a larger fraction of acidification. There is nothing close to the effect of acid deposition on pH of lakes though. That requires a poorly buffered system, which the ocean is not. Still, since marine organisms are sensitive even to subtle changes in pH, it provides yet another reason for controlling emissions of these compounds - especially near China where emissions are skyrocketing. Some other issues I have with your post… the residence times of SO2 or CO2 in the atmosphere have NOTHING to do with their specific gravities (relative to air) as pure gas. If you had a balloon of pure CO2, sure, it would sink in our atmosphere. But you may have noticed that CO2 does not exist as balloons of pure gas in our atmosphere. Rather it is a trace gas mixed among other gasses. The gravitational pull on single molecules is nowhere near enough to offset mixing due to turbulent motion or even Brownian motion. Good thing, too. If CO2 molecules sank they would collect near the surface of the earth and we would all asphyxiate. You and would not be having this edifying discussion. You are right that SO2 IS much more soluble than CO2 in dilute water. Actually sulfate particles for this reason often form nuclei for condensation of droplets – implicating them in cloud formation. It also explains why SO2 gas has a residence time in the atmosphere very similar to water – ie, days – because it rains out with the water. Finally, it explains why SO2 cannot build up in the atmosphere to any great extent or travel much more than 1000 miles from the source. In the US SO2 concentrations in air are typically below the health standard set by the EPA, which is <0.03ppm or >10,000x lower than CO2. Refs Dentener et al., F. (2006b). Nitrogen and sulfur deposition on regional and global scales: a multimodel evaluation. Global Biogeochem. Cycles, 20:GB4003. doi:10.1029/2005GB002672 Doney et al (2007) Impact of anthropogenic atmospheric nitrogen and sulfur deposition on ocean acidification and the inorganic carbon system. PNAS 104:14580-14585.
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