J.B. Smith, Stephen H. Schneider, M. Oppenheimer et al., Assessing dangerous climate change through an update of the IPCC "reasons for concern"

Proceedings of the National Academy of Sciences, Vol. , No. ; Published online before print February 26, 2009; doi: 10.1073/pnas.0812355106

Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) “reasons for concern”

1. Joel B. Smith^a,¹,
2. Stephen H. Schneider^b,^c,¹,
3. Michael Oppenheimer^d,
4. Gary W. Yohe^e,
5. William Hare^f,
6. Michael D. Mastrandrea^c,
7. Anand Patwardhan^g,
8. Ian Burton^h,
9. Jan Corfee-Morlotⁱ,
10. Chris H. D. Magadza^j,
11. Hans-Martin Füssel^f,
12. A. Barrie Pittock^k,
13. Atiq Rahman^l,
14. Avelino Suarez^m and
15. Jean-Pascal van Yperseleⁿ

1. ^aStratus Consulting, Inc., Boulder, CO 80306-4059;
2. ^bDepartment of Biology and
3. ^cWoods Institute for the Environment, Stanford University, Stanford, CA 94305;
4. ^dDepartment of Geosciences and the Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544;
5. ^eDepartment of Economics, Wesleyan University, Middletown, CT 06459;
6. ^fPotsdam Institute for Climate Impact Research, 14473 Potsdam, Germany;
7. ^gShailesh J. Mehta School of Management, Indian Institute of Technology-Bombay Powai, Mumbai 400076, India;
8. ^hUniversity of Toronto, Toronto, ON M6J 2C1 Canada;
9. ⁱOrganisation for Economic Cooperation and Development, 75776 Paris Cedex 16, France;
10. ^jDepartment of Biological Sciences, University Lake Kariba Research Station, Harare, Zimbabwe;
11. ^kCSIRO Marine and Atmospheric Research, Aspendale 3195, Australia;
12. ^lBangladesh Centre for Advanced Studies, Dhaka, 1212 Bangladesh;
13. ^mInstitute of Ecology and Systematic, Cuba Environmental Agency, 10800 Havana, Cuba; and
14. ⁿInstitut d'Astronomie et de Géophysique Georges Lemaître, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium

1. Contributed by Stephen H. Schneider, December 9, 2008 (sent for review March 18, 2008)

Abstract

Article 2 of the United Nations Framework Convention on Climate Change [United Nations (1992) http://unfccc.int/resource/docs/convkp/conveng.pdf. Accessed February 9, 2009] commits signatory nations to stabilizing greenhouse gas concentrations in the atmosphere at a level that “would prevent dangerous anthropogenic interference (DAI) with the climate system.” In an effort to provide some insight into impacts of climate change that might be considered DAI, authors of the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) identified 5 “reasons for concern” (RFCs). Relationships between various impacts reflected in each RFC and increases in global mean temperature (GMT) were portrayed in what has come to be called the “burning embers diagram.” In presenting the “embers” in the TAR, IPCC authors did not assess whether any single RFC was more important than any other; nor did they conclude what level of impacts or what atmospheric concentrations of greenhouse gases would constitute DAI, a value judgment that would be policy prescriptive. Here, we describe revisions of the sensitivities of the RFCs to increases in GMT and a more thorough understanding of the concept of vulnerability that has evolved over the past 8 years. This is based on our expert judgment about new findings in the growing literature since the publication of the TAR in 2001, including literature that was assessed in the IPCC Fourth Assessment Report (AR4), as well as additional research published since AR4. Compared with results reported in the TAR, smaller increases in GMT are now estimated to lead to significant or substantial consequences in the framework of the 5 “reasons for concern.”

• ¹To whom correspondence may be addressed. e-mail: jsmith@stratusconsulting.com or shs@stanford.edu

• Author contributions: J.B.S., S.H.S., M.O., G.W.Y., W.H., M.D.M., A.P., I.B., J.C.-M., C.H.D.M., H.-M.F., A.B.P., A.R., A.S., and J.-P.v.Y. performed research; and J.B.S., S.H.S., M.O., G.W.Y., W.H., M.D.M., A.P., I.B., J.C.-M., C.H.D.M., H.-M.F., A.B.P., A.R., A.S., and J.-P.v.Y. wrote the paper. Conflict of interest statement: The authors declare no conflict of interest. Freely available online through the PNAS open-access option.

Link to abstract: http://www.pnas.org/content/early/2009/02/25/0812355106

Link to free, open-access article (pdf file): http://www.pnas.org/content/early/2009/02/25/0812355106.full.pdf+html