Severe Lake Heatwaves Attributable to Human‐Induced Global Warming

• Published in: Geophysical research letters 2022-02, Vol.49 (4), p.n/a
• Main Authors: Woolway, R. Iestyn, Albergel, Clément, Frölicher, Thomas L., Perroud, Marjorie
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquatic ecosystems; Climate change; Ecosystems; Global warming; Heat waves; Heatwaves; Human influences; Lakes; Mean temperatures; Satellite data; Satellite observation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL097031

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. Plain Language Summary Lake heatwaves are occurring globally with severe negative impacts on lake ecosystems. However, it is currently unclear whether, and by how much, human‐induced global warming contributes to their occurrence. Here, we show that the occurrence probabilities of some of the most severe lake heatwaves observed are extremely sensitive to human influence. We estimated that 94% of severe heatwaves observed in recent decades have an anthropogenic contribution. Globally, severe heatwaves are 3 times more likely in a 1.5°C warmer world and 25 times more likely in a 3.5°C warmer world, compared to a world without anthropogenic warming. To prevent lake ecosystems being adversely affected by the projected increased occurrence of severe heatwaves, ambitious climate targets are of paramount importance. Key Points Severe lake heatwaves have increased in our studied sites by sixfold since 1995 Anthropogenic climate change made the severe heatwaves observed almost twice as likely Continued anthropogenic warming will increase the likelihood occurrence of severe heatwaves this century