Summer dryness in northern mid-latitudes due to increased CO2

Numerical simulations indicate that increases in stratospheric CO2 could lead to increased summer dryness of the land surface in northern middle and high latitudes, with potentially serious consequences for agriculture. In this paper, the dependence of this finding on the representation of the land surface is investigated. It is found that the magnitude of the simulated summer drying is dependent on the physical attributes of the soil, and in certain regions can be reduced or even reversed by an alternative, but equally plausible, treatment of runoff over frozen ground. (C.D.)