Actually, the 450ppm target is for 2050, not for 2020. The 25-40% reduction for Annex I countries (from 1990 levels) is an intermediate target-- sort of a way station. Annex I countries would need to continue to reduce emissions at a similar rate until 2050. Ultimately the Annex I cuts would need to be much deeper to hit 450ppm.
Though I find the Annex I responsibilities a useful way to measure our lack of progress (even in commitments) in the near term (see http://iopscience.iop.org/1748-9326/5/3/034013/fulltext/), they are a confusing way to think about global emissions reductions. I think it is more straightforward to think of it this way. According to the fourth assessment report, by 2050, GLOBAL emissions would need to fall 50-85% from 2000 levels in order to stabilize warming at 2-2.4 degrees Celsius over the pre-industrial equilibrium ( http://www.ipcc.ch/publications_and_data/ar4/wg3/en/spmsspm-d.html see chart SPM.5 ) . Best, Avery On Sun, Aug 5, 2012 at 11:48 AM, Radoslav Dimitrov <[email protected] > wrote: > Depends on the temperature target: To keep global temperature rise below 2 > degrees C, carbon-equivalent atmospheric concentrations must be kept below > 450 ppm - which can be achieved by reducing emissions by 25-40% by 2020. > The latter range is in the 2007 IPCC report and was the policy target > advocated officially by the European Unionat the Bali conference. This was > a subject of intense negotiations. No one else in the industrialized camp > supported the EU on this. As a result, the Bali text only contains a > footnote that *indirectly* refers to the IPCC-endorsed target, without > actually containing the 25-40 numbers. > > Radoslav S. Dimitrov, Ph.D. > Associate Professor > Department of Political Science > University of Western Ontario > Social Science Centre > London, Ontario > Canada N6A 5C2 > Tel. +1(519) 661-2111 ext. 85023 > Fax +1(519) 661-3904 > Email: [email protected] > > On 2012-08-05, at 1:27 PM, VanDeveer, Stacy wrote: > > Hi all,**** > I got a question from a summer school student, and I am trying to find the > ‘consensus’ answer in IPCC documents and I seem to be finding different > numbers. So here is the question: The IPCC estimates that global > emissions must fall by how much, to stabilize the climate systems during > this century. Are the best estimates from the 2007 report (which gives > quite large ranges for each of four warming scenarios)??**** > ** ** > **** > ** ** > ** ** > ** ** > ** ** > ** ** > *Stacy D. VanDeveer* > *Associate Professor***** > *University of New Hampshire* > Dept. of Political Science > Horton SSC > Durham, NH 03824 USA**** > [email protected]**** > tel: > fax: > mobile: > Skype ID:**** > (+1) 603-862-0167 > <http://www.plaxo.com/click_to_call?lang=en&src=jj_signature&To=%28%2B1%29+603%2D862%2D0167&[email protected]> > (+1) 603-862-0178 > (+1) 781-321-5880 > <http://www.plaxo.com/click_to_call?lang=en&src=jj_signature&To=%28%2B1%29+781%2D321%2D5880&[email protected]> > stacy.d.vandeveer**** > ** ** > Want to always have my latest > info?<https://www.plaxo.com/add_me?u=51539758810&src=client_sig_212_1_banner_join&invite=1&lang=en> > **** > Want a signature like > this?<http://www.plaxo.com/signature?src=client_sig_212_1_banner_sig&lang=en> > **** > ** ** > ** ** > ** ** > <image001.jpg>**** > ** ** > ** ** > ** ** > > > -- Avery Simon Cohn | Ph.D. Candidate | Environmental Science, Policy & Management | UC Berkeley | skype: avery.cohn | +1 (510) 410-3731 US
