Why Warming Autumns Are Making Finland’s Lakes Colder Under the Ice

Spend a winter in Finnish Lapland and you quickly learn that lakes are not simply frozen. They are stratified, layered, chemically active places whose temperature at the bottom tells you something about the autumn that preceded them. Which makes a finding published in Water Resources Research this spring particularly unsettling: across roughly 50 years of monitoring data from dozens of Finnish lakes, scientists have found that as autumns grow warmer, the water beneath winter ice is, on average,.