Transient response of a coupled ocean-atmosphere-land surface model to increasing atmospheric carbon dioxide

The increase of atmospheric carbon dioxide affects not only the thermal structure of the coupled model but also its hydrologic cycle. For example, the global mean rates of both precipitation and evaporation increase. The increase in evaporation rate is particularly large in low latitudes and decreases with increasing latitudes. On the other hand, the increase in the precipitation rate is substantial in high latitudes due to the increased penetration of warm, moisture-rich air into high latitudes. Thus, the rate of runoff in the subarctic basin increases markedly. In qualitative agreement with the results of equilibrium response studies, soil moisture is reduced in summer over extensive regions of the middle and high latitudes, such as the North American Great Plains, Western Europe, Northern Canada, and Siberia. -from Authors