Response to Comments on "Heat capacity, time constant, and sensitivity of Earth's climate system." Schwartz S. E. J. Geophys. Res. , Accepted, 2008.

Reanalysis of the autocorrelation of global mean surface temperature prompted by the several Comments, taking into account a subannual autocorrelation of about 0.4 year and bias in the autocorrelation resulting from the short duration of the time series has resulted in an upward revision of the climate system time constant determined in Schwartz [2007] by roughly 70%, to 8.5 ± 2.5 years (all uncertainties are 1-sigma estimates). This results in a like upward revision of the climate sensitivity determined in that paper, to 0.51 ± 0.26 K/(W m-2), corresponding to an equilibrium temperature increase for doubled CO2 of 1.9 ± 1.0 K, somewhat lower than the central estimate of the sensitivity given in the 2007 assessment report of the Intergovernmental Panel on Climate Change, but consistent within the uncertainties of both estimates. The conclusion that global mean surface temperature is in near equilibrium with the applied forcing continues to hold. Forcing over the twentieth century other than that due to greenhouse gases, ascribed mainly to tropospheric aerosols, is estimated as -1.1 ± 0.7 W m-2.


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