Climate Variability of a Coupled Ocean-Atmosphere-Land Surface Model: Implication for the Detection of Global Warming

This lecture evaluates the low-frequency variability of surface air temperature that was obtained from a 1000-yr integration of a coupled ocean-atmosphere-land surface model. The model simulates reasonably well the variability of local and global mean surface air temperature (SAT) at decadal timescales. The physical mechanisms responsible for this variability are explored. Based upon an analysis of the time series of the simulated global mean SAT, it is indicated that the warming trend of ∼0.5°C century^-1 since the end of the last century was not generated internally through the interaction among the atmosphere, ocean, and land surface. Instead, it appears to have been induced by a sustained change in the thermal forcing such as that resulting from changes in atmospheric greenhouse gas concentration, solar irradiance, and aerosol loading.