Hydrology of Northern North America under Global Warming

Northern hydrology is strongly influenced by snow, ice and permafrost. Climatic warming projected by various global climate models (GCMs) for a 2 × CO2 atmosphere suggests that while annual snowfall may or may not decrease in northern North America, the length of the thawed season will increase, at least at the low altitudes. At high elevations, thawing effect is minimized by temperature lapse rates and the ice-sheets may thicken at their accumulation zones while ablation is accelerated at their tongues. Evaporation will increase, and permafrost thaw will enlarge the groundwater storage capacity. Ice cover thickness will diminish and some northern wetlands may be altered. Rainfall generated peak flows will become more prominent as the snowmelt contribution declines. Relative magnitudes of various components of the water balance will change as the northern environment evolves in response to the changing climate.