Why don't those of you dipping a (cold) toe in this arena enter the Sea Ice Outlook comparison held each season by SEARCH?
http://www.arcus.org/search/seaiceoutlook/guidelines (I noticed that WattsUpWithThat did~ ) More on that effort from Dot Earth<http://dotearth.blogs.nytimes.com/?s=%22sea+ice+outlook%22> <http://dotearth.blogs.nytimes.com/?s=%22sea+ice+outlook%22> On Fri, Jul 22, 2011 at 7:19 AM, John Nissen <johnnissen2...@gmail.com>wrote: > Hi David, > > I disagree with your estimation of 12 years and suggest 5 years is more > likely and could even be optimistic, at least for September sea ice decline > to below the 10% mark. > > The PIOMAS graph, updated to end June 2011 here [1], made me think that > 2016 was the most likely date, fitting a curve rather a straight line > because of positive feedback. This is confirmed by Ron Larson from his > analysis, see earlier in thread. You have to work out what the y-axis > anomaly represents. When we get to -14 thousand km-3, which is a gnat's > whisker below the line across the bottom of the graph, I estimate that we'd > have less than 10% of ice volume left in September. Unfortunately [1] does > not give you the vital data as to what the total sea ice volume is that they > are measuring anomaly against! However, you can see that this year is > almost as down on 2007 as 2007 was on the 1979-2010 average. If we assume > that September 2007 was 40% down on the 1979-2010 average (which was true > for the area), the 2011 could be almost 80% down. We only need to reach 90% > down to have 10% sea ice volume left, that Ron talks about as being a > critically low level. That makes the 2016 date seem quite reasonable, if > not optimistic! > > Peter Wadhams points out that the sea ice thickness is decreasing faster > than the sea ice extent. These trends are of course masked by much wind and > weather variability from year to year, which affects ice flow, not just > direct melting. This explains why one can have had relatively little change > in the minimum sea ice extent since September 2007, although the volume has > been declining. > > 64 trillion dollar question* > > If geoengineering is to have a good chance to save the Arctic sea ice, then > it needs to be deployed quickly, building up to maximum strength by summer > 2013. By then the Arctic annually-averaged radiative forcing of the "albedo > flip" (as ice/snow reflection of sunlight turns to sea/land absorption of > sunlight) may exceed 10 Watts per square metre [2]. Could a combination of > SRM methods, with deployment ramped up as fast as possible, have a chance to > exceed 10 W/m-2 of negative forcing in the Arctic by summer 2013, in order > to halt Arctic warming and save the Arctic sea ice? > > Note that cloud brightening and other SRM methods could contribute to > negative forcing by cooling the water flowing into the Arctic, especially > the currents from the North Atlantic. So cooling does not have to be > directly of the Arctic itself. > > Cheers from Chiswick, > > John > > * P.S. It's a 64 trillion dollar question if you consider that losing the > sea ice could have repercussions affecting the total global GDP, which is > around that value. > > [1] > http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ > > [2] > http://www.mail-archive.com/geoengineering@googlegroups.com/msg00660.html > > [geo] Re: Geoengineering - cloud effects > > John Nissen > Wed, 10 Dec 2008 13:42:10 -0800 > --- > > > On Wed, Jul 20, 2011 at 5:50 PM, David Appell <david.app...@gmail.com>wrote: > >> By my estimation of PIOMASS data, September sea-ice could be gone in >> about 12 years: >> >> http://davidappell.blogspot.com/2011/07/arctic-ice-is-at-record-low.html >> >> >> David >> -- >> David Appell, independent science journalist >> e: david.app...@gmail.com >> w: http://www.davidappell.com >> m: St. Helens, OR >> >> >> >> -- >> 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. >> >> > -- > 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. > -- *Please excuse typos; as you may be aware, I had a stroke 1 July<http://dotearth.blogs.nytimes.com/2011/07/01/time-for-a-checkup/> .* ANDREW C. REVKIN Dot Earth blogger, The New York Times http://www.nytimes.com/dotearth Senior Fellow, Pace Acad. for Applied Env. Studies Cell: 914-441-5556 Fax/voicemail: 509-357-0965 Twitter: @revkin Skype: Andrew.Revkin -- 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.
