The intensification of lake sediment heatwaves poses significant risks to aquatic ecosystems. Prolonged and extreme heatwaves can disrupt sediment biogeochemical processes, such as methanogenesis and organic carbon respiration, potentially accelerating greenhouse gas emissions. Additionally, these thermal extremes may impact aquatic biodiversity, particularly species sensitive to temperature changes. Regions with high lake density, such as North America, Europe, and parts of Asia, are likely to experience the most pronounced effects. The study underscores the need for urgent climate mitigation to limit these impacts.