Lakes as indicators of and responders to climate change
Lakes integrate short-term fluctuations in the atmospheric climate. Interannual changes in the response of thermal features, namely, epilimnion and hypolimnion temperatures, thermocline depth, duration of ice cover and freeze and break up dates, can therefore be used to detect and quantify past changes in the climate which are· often obscured by short-term variability and secular changes in meteorological measurements. Given future climatic scenarios and the quantitative relationship with air temperatures, future lake conditions can be estimated. Extensive ice cover and water temperature data for Lake Mendota, Wisconsin, beginning in 1856, are used to demonstrate the utility of historical lake records to detect past changes in mean air temperature. Future lake conditions are forecast in response to projected greenhouse warming scenarios.