| Abstract: Changes in Heat Index (a combined measure of temperature
and humidity) associated with global warming are evaluated based on the
output from four extended integrations of the GFDL coupled ocean-atmosphere
climate model. The four integrations are: a control with constant levels
of atmospheric carbon dioxide (CO2 ), a
second integration in which an estimate of the combined radiative forcing
of greenhouse gases and sulfate aerosols over the period 1765-2065 is used
to force the model, and a third (fourth) integration in which atmospheric
CO2 increases at the rate of 1% per year
to double (quadruple) its initial value, and is held constant thereafter.
While the spatial patterns of the changes in Heat Index are largely determined
by the changes in surface air temperature, increases in atmospheric moisture
can substantially amplify the changes in Heat Index over regions which
are warm and humid in the Control integration. The regions most prone to
this effect include humid regions of the Tropics and summer hemisphere
extra-tropics, including the southeastern United States, India, southeast
Asia and northern Australia. |