The bottoms of lakes are developing heatwaves, and the consequences could be severe - Bangor University

New global study published in Nature Geoscience reveals that extreme heat events are penetrating lake beds worldwide, and threatening freshwater ecosystems and accelerating greenhouse gas emissions.

Scientists have discovered that the mud and sediment at the bottom of lakes is experiencing prolonged bouts of extreme heat, and that these ‘sediment heatwaves’ are set to become far more frequent and severe as the planet warms. The study was led by Dr Iestyn Woolway, a NERC Independent Research Fellow at the School of Ocean Sciences, Bangor University. He was recently recognised as a finalist in the prestigious Blavatnik Awards for Young Scientists, in collaboration with researchers from Pacific Northwest National Laboratory and the University of Helsinki. It is the first study to examine this phenomenon across lakes worldwide.

Lake sediments are not just mud. They are biologically active environments, home to microbes, insects, and other invertebrates, and they play a key role in regulating water quality and controlling the release of greenhouse gases. When they overheat, the consequences ripple through the entire lake ecosystem.

Until now, the temperature of lake beds has been almost impossible to study at scale satellites cannot see through water, and underwater thermometers are scarce. The researchers used computer models to simulate sediment temperatures in over 41,000 lakes, from tropical regions to the Arctic, across both historical records and future climate projections.