Long-Term (2000-2017) Response of Lake-Bottom Temperatures and Talik Configuration to Changes in Climate at Two Adjacent Tundra Lakes, Western Arctic Coast, Canada

Lakes, commonly underlain by taliks, are principal agents of disturbance to permafrost. We have measured lake-bottom temperatures with submerged loggers on near-shore terraces and in deep central pools at two tundra lakes on Richards Island, NT, to determine inter-annual lake thermal responses to climate variation. We have modelled associated potential adjustments in talik geometry. In 2000-17, annual mean temperatures varied between -5.7 and 2.1 degrees C for terraces and 1.1 and 4.5 degrees C for pools. Permafrost in the terraces is warmer than surrounding the lakes: talik configuration varies with horizontal terrace extent and terrace and pool temperatures. The talik break-through depth declines as terrace size increases. Using the four warmest and coldest years as an analogue for climate change-an adjustment that may occur this century-the increase in talik depth may be up to 100 m, but it may take millennia for talik geometry to reach equilibrium.