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Positive Feedbacks

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  • Mike Neuman
    Positive feedbacks of anthropogenic greenhouse gas emissions will cause increasing CO2, N2O, and CH4 levels as a result of continued fossil fuel burning by
    Message 1 of 1 , Jul 19, 2005
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      Positive feedbacks of anthropogenic greenhouse gas emissions will
      cause increasing CO2, N2O, and CH4 levels as a result of continued
      fossil fuel burning by humans. If global warming is not held to
      1°C or less, this climate feedback is likely to cause a large
      nonlinear effect in global temperature, resulting in more rapid global
      warming.

      ABSTRACTS
      Hansen and Sato 2004

      Hansen, J., and Mki. Sato 2004. Greenhouse gas growth rates. Proc.
      Natl. Acad. Sci. 101, 16109-16114, doi:10.1073/pnas.0406982101.

      We posit that feasible reversal of the growth of atmospheric CH4 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 CO2 at an
      achievable level of anthropogenic CO2 emissions, even if the added
      global warming constituting dangerous anthropogenic interference is as
      small as 1°C. A 1°C limit on global warming, with canonical
      climate sensitivity, requires peak CO2 {approx} 440 ppm if further
      non-CO2 forcing is +0.5 W/m2, but peak CO2 ≈ 520 ppm if further
      non-CO2 forcing is -0.5 W/m2. The practical result is that a decline
      of non-CO2 forcings allows climate forcing to be stabilized with a
      significantly higher transient level of CO2 emissions. Increased
      "natural" emissions of CO2, N2O, and CH4 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.

      http://pubs.giss.nasa.gov/docs/2004/2004_HansenSato.pdf
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