Winter ice on lakes across the Northern Hemisphere could shrink by around 40 days by the end of the century if greenhouse gas emissions remain high, according to a new international study published in the Proceedings of the National Academy of Sciences (PNAS).
Researchers analysed ice cover and air temperature data from 724 lakes between 2000 and 2022 and found that lake ice is disappearing much faster than previously expected as the climate warms.
The study revealed that spring ice melt is far more sensitive to rising temperatures than autumn freeze up causing the overall ice covered season to shorten at an accelerating rate.
Scientists identified critical winter temperature thresholds between –13.7°C and –6.8°C. Once average winter temperatures rise above this range, lake ice loss accelerates sharply, with sensitivity to warming increasing by up to 22 times.
Researchers found that broad climate factors particularly winter air temperature and surface albedo (the amount of sunlight reflected by snow and ice) play a much greater role in determining ice loss than a lake’s size, depth or shape.
Currently, about 23% of the studied lakes have already crossed these critical thresholds. Under a high emissions scenario, the study projects that nearly 70% could exceed them by the end of the century.
The researchers warned that shorter ice seasons could have widespread impacts on water quality, freshwater ecosystems, aquatic biodiversity, and communities that rely on stable winter ice cover, with many mid latitude lakes approaching a particularly vulnerable tipping point.