Modelling Lake Ice and the Future of the Arctic Lake Ice Cover

Abstract:

Lake ice cover is a robust indicator of climate variability and change. Recent studies have demonstrated that ice break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. It is important to compare the observed impacts of variability and trends in air temperature and precipitation over the last five decades, with projected trends from climate models in order to quantify future changes in the timing and duration of ice cover (and ice thickness) on Arctic lakes. The Canadian Lake Ice Model (CLIMo) was used to simulate both the contemporary and future lake ice conditions throughout the Arctic. The contemporary climate simulations were driven by both ECMWF ERA-Interim and ERA-40 reanalysis data (1958 – 2011). The future simulations were driven by CORDEX scenarios (Arc-44, 1951-2100), which were produced by the Rossby Centre regional atmospheric model (RCA4) and the Canadian Centre for Climate Modelling and Analysis Canadian Regional Climate Model (CanRCM4). An ensemble of simulated lake ice data was created from five regional model output scenarios using the RCP8.5 emission scenario for the future climate conditions. The 30-year mean ice break-up, freeze-up, and thickness was compared between the scenarios for the entire Arctic region for 1981 – 2010 and 2071 – 2100 to examine the possible changes to the ice cover regimes. Results suggest a mean pan-Arctic reduction in ice cover duration ranging from 42 - 57 days, and a reduction in ice thickness ranging from 0.4 m to 0.7 m, depending on the snow conditions and lake depth used in the simulation. These projected changes could have an important feedback effect on energy, water, and biogeochemical cycling throughout the pan-Arctic region.