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Science
Vol. 339 no. 6117 pp. 280-282
DOI: 10.1126/science.1232468
  • Perspective
Climate Change

The Closing Door of Climate Targets

  1. Thomas F. Stocker
  1. Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland.
  1. E-mail: stocker{at}climate.unibe.ch

Summary

Robust evidence from a range of climate–carbon cycle models shows that the maximum warming relative to pre-industrial times caused by the emissions of carbon dioxide is nearly proportional to the total amount of emitted anthropogenic carbon (1, 2). This proportionality is a reasonable approximation for simulations covering many emissions scenarios for the time frame 1750 to 2500 (1). This linear relationship is remarkable given the different complexities of the models and the wide range of emissions scenarios considered. It has direct implications for the possibility of achieving internationally agreed climate targets such as those mentioned in the Copenhagen Accord and the Cancun Agreements (3, 4). Here I explain some of the implications of the linear relationship between peak warming and total cumulative carbon emissions.