Re the various discussions on sensitivity of late here: remember that Lovelock and Lee Kump have had a simple model for some 15 years in which sensitivity acts, as Lovelock likes to say, "more like a variable than a constant".....perhaps later on climate science will come to organize climate behaviors around specific temperatures rather than absolute abundances of any specific powerful forcer (i.e. CO2)........cheers, Nathan
On Sat, Aug 13, 2011 at 6:20 AM, <[email protected]>wrote: > Today's Topic Summary > > Group: http://groups.google.com/group/geoengineering/topics > > - Jamais Cascio-- on the problematic idea of > 350<#131c2a87be4eff01_group_thread_0>[1 Update] > > Topic: Jamais Cascio-- on the problematic idea of > 350<http://groups.google.com/group/geoengineering/t/adb3265fc3c95801> > > John Nissen <[email protected]> Aug 12 02:53PM +0100 > ^<#131c2a87be4eff01_digest_top> > > Hi Marty, > > I was just looking through some bulky emails to delete them, when I > noticed this one on climate sensitivity. You put 2.5 degrees warming > for CO2 doubling. It is interesting that the climate sensitivity has > been reappraised, e.g. by Hansen giving 3 degrees [1] and by Wasdell > giving a much higher figure of around 7.8 degrees [2]. > > Wasdell raises a fundamental point about the behaviour of the climate > system over recent Ice Ages when temperature has varied by 5 degrees, > yet CO2 has only varied between 180 ppm and 280 ppm. > > [quote from [2]] > / > That raises the fundamental "Emperor's Clothes" question of climate > science: > > 8.5.1 "If the Charney sensitivity, supported by our modern computer > models, projects that a doubling of the concentration of atmospheric > carbon-dioxide leads to a temperature rise of 3ºC at equilibrium, then > why, in the empirically measured behaviour of the planetary system, > does > an increase of only 56% in CO2 concentration (from 180 ppm to 280 ppm) > lead to a 5ºC change in temperature?" > / > [end quote] > > Now that assumes that the CO2 causes the warming (rather than the polar > > amplification of Milankovitch signals, as I would suggest [4]). However > > I think Wasdell is onto something. There does seem to have to been > *systemic optimism* in the climate science community about the effect > of > CO2 emissions on global warming, and we are on course to reach 4 > degrees > or more, even with the most drastic CO2 cuts one could imagine through > a > UNFCCC path (especially given the political situation in US and China). > > Furthermore the potential contribution of Arctic methane to global > warming is being ignored. > > Furthermore, 1.5 degrees is now being accepted as a significantly safer > > target than 2 degrees [3]. And there are calls for the CO2 level to be > quickly brought below 350 ppm, amid concerns about ocean acidification > as well as global warming. > > How much evidence does the scientific community need, before accepting > the requirement for geoengineering? Perhaps those who still say that > geoengineering is too risky (in relation to benefits) should answer > this > question. There are some on this list! > > Cheers, > > John > > [1] > > http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf > > [2] http://www.apollo-gaia.org/Climate%20Sensitivity.pdf > > [3] > > > http://globalwarmingisreal.com/2011/06/03/unfccc-chief-says-two-degrees-is-not-enough/ > > > [4] Nissen, J "Arctic sea ice thermostatic control of global > temperature", EGU 2011 (to be published) > > --- > > On 02/11/2009 17:16, Marty Hoffert wrote: > > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- Nathan Currier 108 Ellwood Street, #43 New York, NY 10040 401-954-3402 www.nathankindcurrier.com -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
