The Arctic and northern subpolar regions are critical for climate change. Ice-albedo feedback amplifies warming in the Arctic, and fluctuations of regional fresh water inflow to the Arctic Ocean modulate the deep ocean circulation and thus exert a strong global influence. By comparing observations to simulations from 22 coupled climate models, the researchers find influence from anthropogenic greenhouse gases and sulfate aerosols in the space-time pattern of precipitation change over high latitude land areas during the second half of the 20th century.