Some questions about the underlying figures: - The pre-industrial temperatures are often presented as the result of sort of an equilibrium between the incoming radiative flux and the outgoing one; having a different set of GHG concentrations would have led to a different equilibrium set of temperatures; hence, stabilizing the GHG concentrations would, ultimately, lead to a new equilibrium; I don't know the value of the asymptotical temperature gap associated with today's GHG concentrations, and of a "typical time constant" to reach it, but I don't think nobody knows them??? (I write: "a typical time constant" because I am aware that the earth is a much more complicated system than a "one generator / one resistor / one capacitor" system, which has indeed only one pure time constant; but, basically, if the positive feedbacks don't overweight the negative ones, time delays are always a matter of thermal inertia. The atmosphere's thermal inertia (which plays an important role together with oceans, continental ground and maybe ice sheets) isn't huge, and the atmosphere frequently undergoes very temperature-sensitive latent heat exchanges. So, with this very simple logic, I thought the atmosphere had a rather short time constant, much smaller than "several decades").
- CO2 lifetime is around one hundred years (at most, two). Hence, if emissions were cut just now, why wouldn't CO2 concentration slowly start decreasing? - If one (the atmosphere) of our three or four major thermodynamic systems has such a thermal inertia that it has sort of a time constant well below several decades, and if the CO2 concentration could asymptotically come back to its pre-industrial value with a time constant around 100 years, what proves that "Even if global emissions were to stop overnight, global warming will continue for thousands of years"? I don't say that geoengineering isn't needed in some cases, e.g. where there is a threat of powerful positive feedbacks. I try not to be a denier of anything. I don't know whether it is realistic to hope that emissions could be cut in some decades. But I can't say that those who argue that strongly reducing the emissions would be a major part of the solution, are liers. Denis. De : [email protected] [mailto:[email protected]] De la part de John Nissen Envoyé : jeudi 11 juin 2009 13:56 À : [email protected]; Geoengineering; [email protected] Cc : John Doyle; paul johnston; Pope, Vicky Objet : [geo] The GREAT LIE about emissions reduction Hi Albert, That paper (on recovery from global warming) nicely illustrates a point about denial: "Abstract. Climate models provide compelling evidence that IF GREENHOUSE GAS EMISSIONS CONTINUE AT PRESENT RATES, then key global temperature thresholds (such as the European Union limit of two degrees of warming since pre-industrial times) are very likely to be crossed in the next few decades." [my capitalisation] However, global temperature thresholds will be crossed in the next few decades, whatever happens to emissions. This first sentence of the abstract illustrates the GREAT LIE being perpetrated by experts: THAT EMISSIONS REDUCTIONS CAN HALT GLOBAL WARMING. The simple truth, as clearly shown by David Keith in his talk to RGS [1], is that there is so much excess CO2 in the atmosphere, and it has such a long effective lifetime, that global warming will continue for thousands of years, unless it is actively taken out of the air. Even if global emissions were to stop overnight, global warming would continue for thousands of years. I believe the reason for perpetrating this lie are threefold: 1) nobody is prepared to face up to the implications, which are indeed terrifying; 2) nobody wants to be the messenger of bad news, for risk of their own reputation; 3) nobody wants to be seen to say anything which might dampen efforts at emissions reduction. I further believe that, because of this great lie, the necessity for geoengineering is not appreciated or it is considered a "last resort" (even by eminent people in this group). And, because emissions reductions obviously cannot cool the Arctic, geoengineering is particularly urgent to save the Arctic sea ice and reduce risk of massive methane discharge and Greenland ice sheet disintegration - a double wammy. But I want to explore that first reason for the "great lie", because denial can a strong effect in all of us, and I've seen it in myself. There is a point when one's realisation is so terrifying (John Doyle calls it the "Oh my God!" point), that the psychological reaction is to suppress that thought. A person facing terminal cancer is liable to behave as if their life would carry on as normal. I witnessed this very behaviour in a good friend, a highly intelligent and clear-thinking man, shortly before his death. He had warned me to expect it (the denial behaviour) from himself, when he was first told that he was suffering from terminal cancer. So it was particularly heart-rending when it happened, the evening before he died. But it brought home to me the power of "Freudian denial" as it is sometimes known [2]. As another example of denial, Jared Diamond, in his excellent book "Collapse: How societies choose to fail or succeed", describes an experiment with people living below a dam. The nearer to the dam they lived, the more concerned, until a point at which the concern vanished. This is the point that some of us have reached, in perpetrating the great lie. And as a result of the lie, the decision makers - the political elite - are failing to perceive the true extent of the problem to be tackled [3]. So what hope have we got? One way that Homo sapiens has evolved to deal with mortal danger is through the fight reaction. If we consider global warming as the number one enemy, then we can face up to the possibility that it could kill us all, if we don't attack it with all the weapons at our disposal. And those weapons include geoengineering as well as drastic emissions cuts. Could the truth be faced, and this fighting spirit be taken to Copenhagen? I believe it can, if enough of you are prepared to expose the great lie for what it is. Cheers from Chiswick, John [1] http://www.21stcenturychallenges.org/challenges/engineering-our-climate-is-there-a-role -for-geoengineering/media-gallery/video/professor-david-keith/ [2] http://en.wikipedia.org/wiki/Denial [3] http://www.youtube.com/watch?v=IESYMFtLIis ---- Veli Albert Kallio wrote: This article provides a good reference point to argue for inevitability of geoengineering, written by non-geoengineers: How difficult is it to recover from dangerous levels of global warming? J A Lowe et al 2009 Environ. Res. Lett. 4 014012 (9pp) doi: 10.1088/1748-9326/4/1/014012<http://dx.doi.org/10.1088/1748-9326/4/1/014012> J A Lowe<http://www.iop.org/EJ/search_author?query2=J%20A%20Lowe&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>1, C Huntingford<http://www.iop.org/EJ/search_author?query2=C%20Huntingford&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>2, S C B Raper<http://www.iop.org/EJ/search_author?query2=S%20C%20B%20Raper&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>3, C D Jones<http://www.iop.org/EJ/search_author?query2=C%20D%20Jones&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>4, S K Liddicoat<http://www.iop.org/EJ/search_author?query2=S%20K%20Liddicoat&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>4 and L K Gohar<http://www.iop.org/EJ/search_author?query2=L%20K%20Gohar&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1>1 1 Met Office Hadley Centre (Reading Unit), Department of Meteorology, University of Reading, Reading RG6 6BB, UK 2 Centre for Ecology and Hydrology, Wallingford OX10 8BB, UK 3 Centre for Air Transport and the Environment, Manchester Metropolitan University, Manchester M1 5GD, UK 4 Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK Abstract. Climate models provide compelling evidence that if greenhouse gas emissions continue at present rates, then key global temperature thresholds (such as the European Union limit of two degrees of warming since pre-industrial times) are very likely to be crossed in the next few decades. However, there is relatively little attention paid to whether, should a dangerous temperature level be exceeded, it is feasible for the global temperature to then return to safer levels in a usefully short time. We focus on the timescales needed to reduce atmospheric greenhouse gases and associated temperatures back below potentially dangerous thresholds, using a state-of-the-art general circulation model. This analysis is extended with a simple climate model to provide uncertainty bounds. We find that even for very large reductions in emissions, temperature reduction is likely to occur at a low rate. Policy-makers need to consider such very long recovery timescales implicit in the Earth system when formulating future emission pathways that have the potential to 'overshoot' particular atmospheric concentrations of greenhouse gases and, more importantly, related temperature levels that might be considered dangerous. For more information on this article, see environmentalresearchweb.org<http://environmentalresearchweb.org/cws/article/futures/38360> Received 9 February 2009, accepted for publication 25 February 2009 Published 11 March 2009 ________________________________ Beyond Hotmail - see what else you can do with Windows Live. Find out more.<http://clk.atdmt.com/UKM/go/134665375/direct/01/> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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