| Abstract: Time lags between changes in
radiative forcing and the resulting simulated climate responses are
investigated in a set of transient climate change experiments.
Both surface air temperature (SAT) and soil moisture responses are
examined. Results suggest that if the radiative forcing is held
fixed at today's levels, the global mean SAT will rise an additional
1.0K before equilibrating. This unrealized warming commitment is
larger than the 0.6K warming observed since 1990. The coupled
atmosphere-ocean GCM's transient SAT response for the year 2000 is
estimated to be similar to its equilibration response to 1980 radiative
forcings - a lag of ~20 years. Both the time lag and the warming
commitment are projected to increase in the future, and depend on the
model's climate sensitivity, oceanic heat uptake, and the forcing
scenario. These results imply that much of the warming due to
current greenhouse gas levels is yet to be realized. |