Severe Lake Heatwaves Attributable to Human-Induced Global Warming

Study key findings & significance

• Severe lake heat waves in the world's largest lakes are twice as likely to occur, on average, as they were during a pre-industrial climate.
• Nearly all severe lake heat waves occurring over the past 20 years were due in some part to climate change, and could become between three and 25 times more likely by the end of the century.

Author quotes

"What really stood out was the magnitude of human contribution: Most of the severe lake heat waves we looked at had a significant anthropogenic imprint...there's no escape for aquatic organisms when they are exposed to these extreme temperatures."

R. Iestyn Woolway, lead author and climate scientist at Bangor University in Wales

Abstract

Much of the focus of global warming impacts on lakes have focused on changes in mean temperature. However, lakes are also highly vulnerable to thermal extremes. Such extremes occur, by definition, during lake heatwaves. Heatwaves in lakes have occurred globally in recent decades and have had severe negative impacts. However, unlike their atmospheric counterparts, it is currently unknown to what extent lake heatwaves are altered by human-induced climate change. Here, we estimate the human contribution to lake heatwaves, specifically focusing on the most severe events. We demonstrate that the occurrence probabilities of severe lake heatwaves increase substantially due to human influence. Our analysis suggests that 94% of severe heatwaves observed during the satellite data-taking period have an anthropogenic contribution. Globally, we suggest that severe heatwaves are 3 and 25- times more likely in a 1.5°C and 3.5°C warmer world, respectively, compared to a world without anthropogenic influence.