Over recent decades, the rate of global mean sea-level rise has increased, although the magnitude—tens of centimetres—remains small from a geological perspective. Such a modest rise in sea level presents a challenge when attempting to assess its global climate impacts, as the signal is weak. However, in previous warmer geological periods, sea levels reached up to tens of metres higher than the present levels. These palaeoclimate periods offer a unique opportunity to investigate the climate effects of higher sea levels. Here, using climate simulations of the Last Interglacial period and a set of present-day sea-level sensitivity experiments, we highlight the importance of global mean sea-level rise in modulating global climate. The lowering of terrestrial elevation and deepening of oceanic bathymetry due to a spatially uniform rise in sea level reorganizes atmospheric and oceanic circulations. Our simulations of the Last Interglacial show that considering this aspect of global mean sea-level rise in isolation from changes associated with land–sea masks or freshwater input reduces the long-lasting model–data mismatch in the Southern Hemisphere. Furthermore, the present-day sensitivity experiments demonstrate that a slight increase in global mean sea level causes substantial adjustments in the global climate, particularly at mid–high latitudes.

近几十年来，全球平均海平面上升的速度有所加快，尽管从地质学的角度来看，幅度（几十厘米）仍然很小。由于信号微弱，海平面如此温和的上升在试图评估其全球气候影响时提出了挑战。然而，在以前较温暖的地质时期，海平面比现在高出几十米。这些古气候时期为研究海平面升高对气候的影响提供了独特的机会。在这里，我们利用末次间冰期的气候模拟和一组现代海平面敏感性实验，强调了全球平均海平面上升在调节全球气候中的重要性。由于海平面在空间上的均匀上升，陆地海拔的降低和海洋测深的加深重新组织了大气和海洋环流。我们对末次间冰期的模拟表明，将全球平均海平面上升的这一方面与陆地-海洋面罩或淡水输入相关的变化隔离开来，可以减少南半球长期持续的模型-数据不匹配。此外，当今的敏感性实验表明，全球平均海平面的轻微上升会导致全球气候发生重大调整，特别是在中高纬度地区。我们对末次间冰期的模拟表明，将全球平均海平面上升的这一方面与陆地-海洋面罩或淡水输入相关的变化隔离开来，可以减少南半球长期持续的模型-数据不匹配。此外，当今的敏感性实验表明，全球平均海平面的轻微上升会导致全球气候发生重大调整，特别是在中高纬度地区。我们对末次间冰期的模拟表明，将全球平均海平面上升的这一方面与陆地-海洋面罩或淡水输入相关的变化隔离开来，可以减少南半球长期持续的模型-数据不匹配。此外，当今的敏感性实验表明，全球平均海平面的轻微上升会导致全球气候发生重大调整，特别是在中高纬度地区。