Simulating thermokarst lakes



Thermokarst lakes, which form from thawing permafrost, alter landscapes and hydrology and can release significant amounts of methane to the atmosphere. To learn more about the dynamics of thermokarst lakes, Kessler et al. created a three-dimensional numerical model of these lakes that includes the surrounding topography. They simulated 10,000 years of evolution of two small thermokarst lakes on the northern Seward Peninsula in Alaska and studied the pattern of methane production and emission over time. They found that the rate of methane production depends on the rate of expansion of thermokarst lakes into ancient permafrost and that local topography strongly influences the rate of expansion and drainage of the lakes. One lake, located in relatively flat surroundings, expanded rapidly and drained many times, while the other, surrounded by steeper slopes, grew more slowly and drained only partially. Thus, topography is an important control on thermokarst lake dynamics and methane emission. (Journal of Geophysical Research-Biogeosciences, doi:10.1029/2011JG001796, 2012)