REGIONAL WATER TEMPERATURE CHARACTERISTICS OF LAKES SUBJECTED TO CLIMATE-CHANGE

A deterministic, validated, one-dimensional, unsteady-state lake water quality model was linked to a daily weather data base to simulate dai ly water temperature profiles in lakes over a period of twenty-five (1 955-79) years. Twenty seven classes of lakes which are characteristic for the north-central U.S. were investigated. Output from a global cli mate model (GISS) was used to modify the weather data base to account for a doubling of atmospheric CO2. The simulations predict that, after climate change, epilimnetic temperatures will be higher but increase less than air temperature, hypolimnetic temperatures in seasonally str atified dimictic lakes will be largely unchanged or even lower than at present, evaporative water loss will be increased by as much as 300 m m for the season, onset of stratification will occur earlier and overt urn later in the season, and overall lake stability will become greate r in spring and summer.