You are currently viewing the summary.View Full Text
Even the coldest environments on Earth have enough liquid water to sustain life. The scope for biological productivity in the polar regions is constrained by low temperatures and low annual levels of solar radiation, but free water on or under glaciers or ice sheets nevertheless contains numerous species of mostly microorganisms. These delicate ecosystems are widely regarded as sentinels of climate change. Recent studies of polar and glacial lakes, as well as subglacial environments, have shed light on how these ecosystems function and on the role that they play in nutrient cycling.