摘要：The radiative kernel technique is employed to quantify twenty-first century changes to the
tropospheric energy budget in the Intergovernmental Panel on Climate Change
(IPCC) Fourth Assessment Report (AR4) models in order to better understand
changes in global-mean precipitation. The strongest feedbacks on the tropospheric
radiative cooling are found to be associated with increases in temperature and
water vapor, with the water vapor feedback offsetting a significant portion (~39%) of the increase in radiative cooling due to higher temperatures. Cloud and surface sensible
heat flux feedbacks, though not as large in magnitude as the temperature and water vapor
feedbacks, are important contributors to the intermodel difference in the global
precipitation response to warming, or hydrological sensitivity. The direct effects of
radiative forcing agents on the tropospheric energy budget are also important. Rising
CO2 levels reduce tropospheric radiative cooling and hence limit the increase in global rainfall.
Additionally, in some of the models, further reductions in radiative cooling occur due
to increases in absorbing aerosol, suggesting that differences in aerosol forcing
can explain part of the difference in hydrological sensitivity between models.
