[geo] Re: [SUMMARY] Re: Need citations showing IPCC too conservative

[John Nissen]

Hi Manu, Re Arctic sea ice retreat... On the modelling side, the Climate Safety report gave this reference: http://www.nature.com/climate/2008/0811/full/climate.2008.108.html This itself gives some references.  Mark Sereze is one of the leading researchers on Arctic sea ice.  He may be able point you to some papers of the kind you are looking for, especially on sea ice thickness.  The trouble is that a lot of the most up-to-date information and expert views have not had time to go through the process of publication with peer reviews.  Perhaps Mark can point you to some papers that are due for publication.  Note that the forecasting can change in the light of recent events, e.g. sea ice minimum extent this year. Of course we would all like certainty, so there is a natural tendency to claim more accuracy than is justified.  See "central estimate bias" [1].  Thus where there might be an estimate for summer sea ice disappearance in 2030 as most likely date, there might be (at near end of distribution) a 5 percentile of disappearance within, say five years, and (at far end of distribution) a 5 percentile after, say, 2100. BTW, this article ([1]) is well worth reading for an understanding of why we humans don't "get" dangerous climate change.  And if we don't appreciate the danger, we don't appreciate the urgent need for geoengineering to help stave it off!  Geoengineering is really all about sensible risk management, where the stakes are as high as you could possibly imagine. Cheers, John [1] http://westcoastclimateequity.org/?p=3078 -- Manu Sharma wrote: Hi John, Ron, Thanks for the replies and suggestions.  John, I tried to avoid media reports and limit references to peer-reviewed scientific work but I've made an exception in this case and included the new scientist report you mention on top of the list as it provides context for the references below. I was aware of this but it's great to have a non-anecdotal reference based on research.  Also made three more additions, Monaco declaration on ocean acidification, a paper on long-term oxygen depletion in oceans and the recent UCL conference on geological hazards.  I looked for papers on ice thickness that could be included. Please mention any that you come across that reflect IPCC AR4 in poor light.  An updated version of the list is attached.  Thanks, Manu On Fri, Oct 30, 2009 at 4:37 AM, John Nissen <j...@cloudworld.co.uk> wrote: Hi Ron, Manu, There was a lot of criticism of the IPCC report by David Wasdell, reported in the New Scientist: http://www.newscientist.com/article/mg19325943.900-climate-report-was-watered-down.html His criticism is objected to by IPCC authors, who replied via New Scientist: http://www.newscientist.com/article/mg19325960.900-climate-with-care.html However the IPCC authors do not address Wasdell's main criticism - that the IPCC did not take positive feedbacks (in the Earth system) into due consideration.  He is backed up by Peter Wadhams, who is particularly concerned about the rapid retreat of Arctic sea ice. The process, by which IPCC came to produce their figures, tended to ignore positive feedback, because this is difficult to model, and hence the main feedbacks (such as albedo flip in Arctic - when reflective ice turns to  sun-absorbing water) were ignored. The ignoring of the positive feedbacks in the Arctic continues to bedevil the generally accepted view of global warming - that it is essentially linear, so final temperature is directly proportional to atmospheric CO2, and the slope = climate sensitivity.    To illustrate my point, consider the warming of the Arctic.  If there is 4 degrees global warming, then the Arctic warms by 15 or 16 degrees, according to Met Office regional responses (attached to Albert Kallio email).  Such warming would certainly result in massive methane release, providing catastrophic positive feedback to global warming, and making a nonsense of climate sensitivity. I believe my argument is really common sense, yet there seems little of it around.  The danger from the Arctic is well presented in a report "Climate Safety" (worth reading, but conclusions on geoengineering are rubbish): http://www.pirc.info/content/view/60/54/ Hansen is very good reading and sound science.  But even he does not take sufficient account of positive feedback.  Positive feedback provides a growing forcing on the climate system, which can be expressed in Watts per square metre, yet Hansen and IPCC treat positive feedback as an "amplification" rather than a forcing.  Thus it does not appear in their diagram of the various contributions to the net 1.6 Watts/m-2 forcing that they estimate.  See for example in Hansen: http://www.columbia.edu/~jeh1/2009/Copenhagen_20090311.pdf Note that Wasdell considers that the positive feedback from water vapour (a greenhouse gas) is very significant, and could already be contributing more than 1.6 Watts/m-2 to global warming.  But this should be the subject of another thread! Cheers from Chiswick, John P.S.  I disagree with David Schnare when he says that 4 degrees is unrealistic.  At least 4 degrees global warming seems all too likely with current emissions trajectory - even without the positive feedbacks I mention.  That is why the recent Oxford conference was titled "4 degrees plus"! http://www.eci.ox.ac.uk/4degrees/index.php -- Ron Larson wrote: Manu (cc list) Your attachment was very helpful. I would add (and will try to find references, but others may have them readily): a. arctic ice thickness. (This is dropping more rapidly than areal extent; clearly they both have to go to zero at the same time.) b. rate of glacial retreat c. Ocean pH level change Ron Manu Sharma wrote: Members, A few days ago I had asked for citations of scientific literature published over the last two years that show IPCC projections to be too conservative. To view the final list I compiled, view attachment. Thanks for all who responded: <snip> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---