The influence of potential greenhouse warming on Great Lakes hydrology, water levels, and water management

As part of the U.S. National Climate Change Assessment, estimates were made of changes in net basin water supply (precipitation plus runoff minus lake evaporation) for the drainage basin of the Laurention Great Lakes due to the influence of increased greenhouse gases. Data generated by state-of-the-art General Circulation Models from the Canadian Climate Centre and the Hadley Centre were used to make adjustments to observed data for temperature, precipitation, cloud cover, relative humidity, and wind speed. The adjusted and unadjusted data were then fed to a system of rainfall/runoff, lake evaporation, hydrologic routing, and water management models for the Great Lakes system to assess hydrologic and water management changes. The results with respect to anticipated lake levels for 2030 ranged from a small rise to a drop of 40-104 cm, depending on the lake. Connecting channel flows ranged from almost no change to decreases on the order of 25%. The regulation plan for Lake Ontario was unable to satisfy its operational criteria under the General Circulation Model scenarios and would have to be revised.