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Rapid acceleration of ice-cover loss from Northern Hemisphere lakes above critical air temperature thresholds
How reliable would future forecasts be if ecosystems suddenly accelerated their response to climate change? Work by Jian Zhou of the Nanjing Normal University and international colleagues addresses this question for freshwater lakes. They measured ice on and off dates of over 700 global lakes and showed that as winter temperatures rise above critical thresholds of between -14 and -7oC, rates of ice melting will accelerate by over 2000%. Advances in the dates of spring ice melt were much more sensitive to winter warming than were delays in date of ice formation, meaning that spring ice conditions are becoming more decidedly less predictable, while overall ice cover is declining. Modeling of future conditions suggests that total ice cover will decline by over a month under business as usual scenarios where fossil fuel use is not controlled before the 22nd century, with around 70% of lakes exhibiting sudden increases in rates of ice loss. The most sensitive lakes are predicted to be mid-latitude systems in the northern United States, southern Canada, and Europe.
