Greenhouse gas growth rates.

We posit that feasible reversal of the growth of atmospheric CH(4) and other trace gases would provide a vital contribution toward averting dangerous anthropogenic interference with global climate. Such trace gas reductions may allow stabilization of atmospheric CO(2) at an achievable level of anthropogenic CO(2) emissions, even if the added global warming constituting dangerous anthropogenic interference is as small as 1 degrees C. A 1 degrees C limit on global warming, with canonical climate sensitivity, requires peak CO(2) approximately 440 ppm if further non-CO(2) forcing is +0.5 W/m(2), but peak CO(2) approximately 520 ppm if further non-CO(2) forcing is -0.5 W/m(2). The practical result is that a decline of non-CO(2) forcings allows climate forcing to be stabilized with a significantly higher transient level of CO(2) emissions. Increased "natural" emissions of CO(2), N(2)O, and CH(4) are expected in response to global warming. These emissions, an indirect effect of all climate forcings, are small compared with human-made climate forcing and occur on a time scale of a few centuries, but they tend to aggravate the task of stabilizing atmospheric composition.

[1]  J. Hansen,et al.  Soot climate forcing via snow and ice albedos. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[2]  G. Dvali.  Out of the darkness. , 2004, Scientific American.

[3]  W. Broecker,et al.  Fate of Fossil Fuel Carbon Dioxide and the Global Carbon Budget , 1979, Science.

[4]  M. Noguer,et al.  Climate change 2001: The scientific basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change , 2002 .

[5]  P. Jones,et al.  Hemispheric and Large-Scale Surface Air Temperature Variations: An Extensive Revision and an Update to 2001. , 2003 .

[6]  J. Hansen,et al.  Radiative forcing and climate response , 1997 .

[7]  K. Cuffey,et al.  Covariation of carbon dioxide and temperature from the Vostok ice core after deuterium-excess correction , 2001, Nature.

[8]  Nicolas Gruber,et al.  The Oceanic Sink for Anthropogenic CO2 , 2004, Science.

[9]  J. Jouzel,et al.  Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica , 1999, Nature.

[10]  Stauffer,et al.  Variations in atmospheric N2O concentration during abrupt climatic changes , 1999, Science.

[11]  Makiko Sato,et al.  A closer look at United States and global surface temperature change , 2001 .

[12]  E. Maier‐Reimer,et al.  Dynamics of fossil fuel CO2 neutralization by marine CaCO3 , 1998 .

[13]  Jean Jouzel,et al.  New insights into Southern Hemisphere temperature changes from Vostok ice cores using deuterium excess correction , 2002 .

[14]  J. Hansen,et al.  Global warming in the twenty-first century: an alternative scenario. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[15]  Smith,et al.  Ice core records of atmospheric CO2 around the last three glacial terminations , 1999, Science.

[16]  V. Ramanathan,et al.  Aerosols, Climate, and the Hydrological Cycle , 2001, Science.

[17]  J. Hansen,et al.  Greenhouse effect of chlorofluorocarbons and other trace gases , 1989 .

[18]  B. O’Neill,et al.  Dangerous Climate Impacts and the Kyoto Protocol , 2002, Science.

[19]  S. Levitus,et al.  Warming of the World Ocean , 2000 .