I agree that reduction in snow or ice cover resulting from warming constitutes a likely slow positive feedback, but its magnitude may be quite small, at least for
the modest changes in surface temperature that can be expected to arise if sensitivity is in fact fairly low, so the Forster / Gregory 06 results may nevertheless be a close approximation to a measurement of equilibrium climate sensitivity.
Not exact matches
Global average
surface temperatures are not expected to
change significantly although
temperatures at higher latitudes may be expected to decrease to a
modest extent because of a reduction
in the efficiency of meridional heat transport (offsetting the additional warming anticipated for this environment caused by the build - up of greenhouse gases).
In March 2009, Michaels, under the auspices of the Cato Institute, circulated a draft advertisement that stated: «
Surface temperature changes over the past century have been episodic and
modest and there has been no net global warming for over a decade now... The computer models forecasting rapid
temperature change abjectly fail to explain recent climate behavior.»
Given the vast pool of very cold water
in the deep ocean, even
modest changes in the rate it exchanges heat with the
surface can produce large
changes in temperature without any
change in the planetary radiative balance.
Scientific confidence of the occurrence of climate
change include, for example, that over at least the last 50 years there have been increases
in the atmospheric concentration of CO2; increased nitrogen and soot (black carbon) deposition;
changes in the
surface heat and moisture fluxes over land; increases
in lower tropospheric and upper ocean
temperatures and ocean heat content; the elevation of sea level; and a large decrease
in summer Arctic sea ice coverage and a
modest increase
in Antarctic sea ice coverage.