The Greenhouse Development Rights project has just released a brief report (only 10 pages) entitled “A 350 ppm Emergency Pathway.” It is posted at http://gdrights.org/2009/10/25/a-350-ppm…
In this paper, for the first time, a precise and up-to-date representative 350 ppm pathway is developed.  Like so:

The 350 target reflects a scientifically-grounded assessment of what global climate protection really means.  But what would it actually take to bring the atmospheric carbon-dioxide (CO2) concentration back to 350 parts per million?  This memo provides a quick, up-to-date overview of the issues here – issues significant to any plausible emergency emissions reduction target.  To that end, it focuses on the extremely limited size of the remaining global CO2 budget, and on the emissions pathways that would enable us to keep within it.  And, by way of context, it compares 350 to the 2°C temperature target, and offers a very brief glimpse of the challenges that such emergency targets raise on this North / South divided world.

The pathway is derived from the core 350 pathway developed by Jim Hansen’s team, and, critically, it is updated to take account to the 2007-2009 global emissions decline that came about with the “great recession.”  Moreover, it is based on the milestone methodology published earlier this year in Nature (see our discussion and links here) by a team led by Malte Meinshausen, which finally established cumulative emissions budgets as the best predictors of success for any given global emissions pathway.

Here, as a teaser, is an unexplained picture of our representative 350 pathway:

Feedback is very much welcome — to  gdrs_authors at googlegroups.com

– toma

–
Tom Athanasiou

EcoEquity
 toma at ecoequity.org
1-510-859-9170 (office)

c/o Earth Island Institute
2150 Allston Way, Suite 460
Berkeley, CA 94704-1302