ИСТИНА

Freshwater lakes provide numerous ecosystem services, are both sensitive indicators of climate change and hot spots of biogeochemical processing, affecting the gas exchange and energy and energy balance of the surrounding landscape. Emerging evidence indicates that lakes have been affected and continue to be affected by our changing climate, with consequent changes in water temperature, thermal structure and biogeochemistry. Clearly, useful generalizations can be made, but the effects on specific lakes are variable in relation to characteristics of the lake, its watershed and the sequence of climate forcing. To better understand the global impact of climate change on lakes the ISIMIP lake sector is evaluating lake response to ISIMIP phase 2b scenarios. Two distinct and complementary approaches are being used to make initial simulations of the impacts on lake thermal structure. A global strategy where all land-grid cells are analyzed using generic models that requires minimal calibration and parameterization A site specific strategy using more complex lake models where data for model calibration and verification are available. Lake models will be consistently calibrated using historical forcing data from ISIMIP phase 2a against records of measured water temperature. Several different lake models are being used with each strategy. In this presentation we provide an initial evaluation of the climate change impacts simulated by each modeling approach. From sites where it is possible to make calibrated model simulations, we compare the results from both strategies using simulations from the site specific strategy (including simulations from the models used in the global strategy that are locally calibrated) and uncalibrated simulations from the global strategy. This will provide valuable insights for developing long-term methodologies for upscaling local studies to the global scale.