Lake heatwaves will become hotter and longer lasting

Lake heatwaves are expected to become hotter and last longer by the end of this century, according to a new report from the European Space Agency (ESA).

The study has revealed that the average duration of lake heatwaves could increase by an average of three months under a high greenhouse gas scenario. For some lakes, the shift will be permanent.

Prior to this research, little was known about how global warming will affect the frequency and duration of lake heatwaves, which are characterized by periods of extremely warm surface water temperatures. 

To investigate, a team led by Iestyn Woolway modeled the impact of heatwaves on 702 lakes worldwide from 1901 to 2099. 

The researchers found, for the first time, that heatwaves frequently occur in lakes, and that these extreme events are very sensitive to climate variations.

The projections indicate that lake heatwaves will become progressively worse over the course of this century, especially if greenhouse gas emissions are not reduced. The average duration will increase from around a week to more than three months by 2100.

Even under a conservative emissions scenario, the heatwaves will become hotter and last a month longer on average. According to the study authors, the heatwaves will be less intense but longer lasting in deep lakes.

The researchers explained that as lakes warm up over the 21st century, heatwaves will extend across all seasons and some lakes will reach a permanent heatwave state.

“Agencies from around the world recently reported that 2020 was part of the warmest decade on record, and climate projections suggest that this warming will continue,” said Woodway.

“Unless climate change is mitigated, our projections suggest that lake heatwaves will become increasingly severe this century, threatening lake biodiversity and pushing ecosystems to the limits of their resilience.”

The research was made possible by the use of long-term satellite observation records generated by ESA’s Climate Change Initiative.

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By Chrissy Sexton, Earth.com Staff Writer