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Wednesday, January 28, 2009

S. Solomon, G.-K. Plattner, R. Knutti, P. Friedlingstein, PNAS: Irreversible climate change due to carbon dioxide emissions

Proceedings of the National Academy of Sciences, January 28, 2009;

Irreversible climate change due to carbon dioxide emissions

Susan Solomon¹ (Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, U.S.A.), Gian-Kasper Plattner (Institute of Biogeochemistry and Pollutant Dynamics, ETH, CH-8092, Zurich, Switzerland), Reto Knutti (Institute for Atmospheric and Climate Science, ETH CH-8092, Zurich, Switzerland), and Pierre Friedlingstein (Institut Pierre Simon Laplace/Laboratoire des Sciences du Climat et de l'Environnement, Unité Mixte de Recherche 1572 Commissariat à l'Energie Atomique–Centre National de la Recherche Scientifique–Université Versailles Saint-Quentin, Commissariat a l'Energie Atomique-Saclay, l'Orme des Merisiers, 91191 Gif sur Yvette, France)

¹Contributed by Susan Solomon, December 16, 2008 (sent for review November 12, 2008)


The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO2 concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.

  • 1To whom correspondence should be addressed. e-mail:
  • Author contributions: S.S., G.-K.P., R.K., and P.F. designed research; S.S., G.-K.P., and R.K. performed research; G.-K.P. and R.K. analyzed data; and S.S., G.-K.P., R.K., and P.F. wrote the paper.

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