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

Abstract 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.