Lake bottoms are warming, but it depends greatly on the depth of lakes and how thick ice grows in the winter. New research published (Arp et al. 2016 Geophysical Research Letters) shows how shallow lakes are warming rapidly and crossing a threshold that is expected to initiate sublake permafrost thaw across vast regions of arctic lowlands. Warming rates are similar to shallow terrestrial permafost, but is still very cold. Deeper lakes are warming slowly and thawed sublake permafrost long ago to form deep taliks. Listen to an interview on this research on Radio Canada's Eye on the Arctic.