Lake surface temperatures are projected to increase under climate change, which could trigger shifts in the future distribution of thermally sensitive aquatic species. Of particular concern for lake ecosystems are when temperatures increase outside the range of natural variability, without analogue either today or in the past. However, our knowledge of when such no-analogue conditions will appear remains uncertain. Here, using daily outputs from a large ensemble of SSP3-7.0 Earth system model projections, we show that these conditions will emerge at the surface of many northern lakes under a global warming of 4.0 °C above pre-industrial conditions. No-analogue conditions will occur sooner, under 2.4 °C of warming, at lower latitudes, primarily due to a weaker range of natural variability, which increases the likelihood of the upper natural limit of lake temperature being exceeded. Similar patterns are also projected in subsurface water, with no-analogue conditions occurring first at low latitudes and occurring last, if at all, at higher latitudes. Our study suggests that global warming will induce changes across the water column, particularly at low latitudes, leading to the emergence of unparalleled climates with no modern counterparts, probably affecting their habitability and leading to rearrangements of freshwater habitats this century.

预计气候变化导致湖面温度上升，这可能会引发热敏感水生物种未来分布的变化。湖泊生态系统特别值得关注的是温度升高超出自然变化范围的情况，无论是现在还是过去都没有类似的情况。然而，我们对何时出现这种非模拟情况的了解仍然不确定。在这里，我们使用 SSP3-7.0 地球系统模型预测的大型集合的每日输出，表明在全球变暖比工业化前条件高 4.0 °C 的情况下，这些条件将出现在许多北部湖泊的表面。在低纬度地区，升温幅度为 2.4°C 时，无类似条件会更快出现，这主要是由于自然变率范围较弱，这增加了超过湖泊温度自然上限的可能性。类似的模式也出现在地下水中，无类似条件首先出现在低纬度地区，最后出现（如果有的话）出现在高纬度地区。我们的研究表明，全球变暖将引起整个水体的变化，特别是在低纬度地区，导致出现现代气候所没有的无与伦比的气候，可能会影响它们的宜居性，并导致本世纪淡水栖息地的重新排列。