Hot temperature extremes (HTEs) in the atmosphere can also affect lake surface water temperature, but how this impact changes with global warming is not well understood. Here we use numerical modelling and satellite observations to quantify the contribution of HTEs to variations in summer lake surface water temperature and lake heatwaves in 1,260 water bodies worldwide between 1979 and 2022. Over this time period, HTE duration and cumulative intensity over the studied lakes increased significantly, at average rates of 1.4 days per decade and 0.92 °C days per decade, respectively. Despite only accounting for 7% of the total summer days, HTEs are responsible for 24% of lake surface summer warming trends, with the most pronounced effect observed in Europe at 27%. Moreover, HTEs are key drivers of both the duration and cumulative intensity of lake heatwaves. Our findings underscore the pivotal role played by short-term climatic extreme events in shaping long-term lake surface water temperature dynamics.

大气中的极端高温（HTE）也会影响湖面水温，但这种影响如何随着全球变暖而变化尚不清楚。在这里，我们使用数值模型和卫星观测来量化 HTE 对 1979 年至 2022 年间全球 1,260 个水体夏季湖泊表面水温和湖泊热浪变化的贡献。在此期间，所研究湖泊的 HTE 持续时间和累积强度增加显着，平均速率分别为每十年 1.4 天和每十年 0.92 °C 天。尽管 HTE 只占夏季总日数的 7%，但它却对湖面夏季变暖趋势造成了 24% 的影响，其中在欧洲观察到的影响最明显，达到 27%。此外，HTE 是湖泊热浪持续时间和累积强度的关键驱动因素。我们的研究结果强调了短期气候极端事件在塑造长期湖泊表面水温动态方面发挥的关键作用。