Response of Northern Hemisphere lake-ice cover and lake-water thermal structure patterns to a changing climate

The formation and break-up of ice-cover are important seasonal events in mid- to high-latitude cold-region lakes. There is increasing concern regarding how climate change will affect lake-water thermal structure and lake-ice characteristics, particularly ice formation, duration, break-up, thickness, and composition. This study employs a one-dimensional process-based multi-year lake ice model, MyLake, to simulate the evolution of the Northern Hemisphere lake-ice and thermal structure patterns under a changing climate. After testing the model on Baker Lake located in Nunavut Canada, large-scale simulations were conducted over the major land masses of the Northern Hemisphere subarctic regions between 40° and 75°N using hypothetical lakes positioned at 2·5° latitude and longitude resolution. For the baseline period of 1960–1999, the lake-ice model was driven by gridded atmospheric forcings from the ERA-40 global reanalysis data set while atmospheric model forcings corresponding to future (2040–2079) climate were obtained by modifying the ERA-40 data according to the Canadian Global Climate Model projection based on the SRES A2 emissions scenario. Analysis of the modelling results indicates that lake-ice freeze-up timing will be delayed by 5–20 days and break-up will be advanced by approximately 10–30 days, thereby resulting in an overall decrease in lake-ice duration by about 15–50 days. Maximum lake-ice thickness will also be reduced by 10–50 cm. The change in maximum snow depth on the lake-ice ranges between − 15 to + 5 cm, while the change in white-ice thickness ranges between − 20 to + 10 cm depending on the geographic location and other climate parameters. The future warming will also result in an overall increase in lake-water temperature, with summer stratification starting earlier and extending later into the year. Copyright © 2011 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.