Warming pushes Northern Hemisphere lakes past winter ice thresholds

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An international study published in PNAS analyzed ice records and air temperatures for 724 Northern Hemisphere lakes from 2000 to 2022 and found that lake ice loss accelerates sharply after winter air temperatures exceed thresholds between -13.7 °C and -6.8 °C. Spring ice-off dates are far more sensitive to warming than autumn freeze-up, and phenological sensitivity can increase up to 22-fold once thresholds are crossed. Under a high-emission scenario, winter ice-cover duration could shrink by roughly 40 days by the end of the century and the share of lakes past thresholds may rise from 23 percent to 70 percent, with consequences for water quality, aquatic ecosystems, and northern communities.

Many mid-latitude lakes could lose about 40 days of ice.