Widespread loss of lake ice around the Northern Hemisphere in a warming world

Ice provides a range of ecosystem services, including fish harvest, cultural traditions, transportation, recreation, and regulation of the hydrologic cycle, to more than half of the world's 117 million lakes. One of the earliest observed impacts of climatic warming has been the loss of freshwater ice, with corresponding climatic and ecological consequences. However, while trends in ice cover phenology have been widely documented, a comprehensive large-scale assessment of lake ice loss is absent. Here, using observations from 513 lakes around the Northern Hemisphere, we identify lakes vulnerable to ice-free winters. Our analyses reveal the importance of air temperature, lake depth, elevation, and shoreline complexity in governing ice cover. We estimate that 14,800 lakes currently experience intermittent winter ice cover, increasing to 35,300 and 230,400 at 2degC and 8degC, respectively, impacting up to 394 and 656 million people. Our study illustrates that an extensive loss of lake ice will occur within the next generation, stressing the importance of climate mitigation strategies to preserve ecosystem structure and function, as well as local winter cultural heritage.

全球1.17亿个天然湖泊中，逾半数依托湖冰（lake ice）提供多种生态系统服务，涵盖渔业捕捞、文化传承、交通运输、休闲娱乐以及水文循环调节功能。气候变暖最早被观测到的影响之一便是淡水冰的消融，并伴随相应的气候与生态后果。尽管冰盖物候（ice cover phenology）的变化趋势已得到广泛记录，但目前仍缺乏针对湖泊冰盖消融的系统性大尺度评估。本研究基于北半球513个湖泊的观测数据，识别出冬季可能出现无冰状态的脆弱湖泊。分析结果显示，气温、湖泊水深、海拔与岸线复杂度是调控湖冰覆盖的核心影响因子。本研究估算，当前约有1.48万个湖泊冬季存在间歇性冰盖；在升温2℃与8℃的情景下，该数量将分别增至3.53万个与23.04万个，受影响人口最多可达3.94亿与6.56亿。本研究表明，未来一代人的时间尺度内，全球湖泊冰盖将出现大范围消融，凸显气候减缓策略对于保护生态系统结构与功能，以及当地冬季文化遗产的重要性。