Northern hemisphere lake ice cover under contemporary and future climate conditions

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Lake-ice cover has been shown to be a robust indicator of climate variability and change. Recent studies have demonstrated that break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere (NH) over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. Break-up dates, and to a lesser extent freeze-up dates, have been shown to be strongly related to the variability and trends in the 0oC isotherm dates as well as large-scale atmospheric and oceanic circulation patterns (teleconnections), particularly in western North America. The impacts of recently documented trends in air temperature and winter precipitation over the last five decades and those projected by global climate models could be significant on the timing, duration, thickness, and composition of ice cover at northern latitudes. This could, in turn, have an important effect on energy, water and biogeochemical cycling, and aquatic ecosystems in various regions of the NH. How lake-ice cover has changed over the last five decades, and what will likely be the impacts of projected 21st century climate warming on ice cover for lakes of various depths in different regions of the NH are questions that must be examined in order to gain a deeper understanding of climate-lake interactions at northern latitudes. The proposed research program will seek to answer these pressing questions. The overall goal will be to provide a NH synthesis of the temporal and spatial variability and trends in lake ice cover in relation to teleconnection patterns during the second half of the 20th century, and plausible scenarios of the response of lake ice cover to projected future climate conditions. Results from this research will contribute critical data and information during the International Polar Year (IPY) period as well as to international climate change programs (e.g. Climate and Cryosphere (CliC), Global Climate Observing System (GCOS), Integrated Global Observing System (IGOS) - Cryosphere) and assessments such as the International Panel on Climate Change (IPCC).