Revisiting the Relationship Between Changes in Global‐Mean Surface Air Temperature and Sea Surface Temperature at the Last Glacial Maximum

Abstract The relationship between changes in surface air temperature and sea surface temperature is important for understanding past and future climate change. In this study, we use reconstructions and model simulations to investigate the ratio of global mean air versus sea surface temperature change ( S ) during the Last Glacial Maximum (LGM). The simulated S at the LGM is 1.97 ± 0.22 (1σ), 44 ± 16% greater than under future warming, primarily due to the influence of elevated continental ice sheets. Results reveal that the glacial air‐sea cooling contrast is negatively related to the magnitude of sea surface cooling, consistent with a simple moist static energy theory. This relationship can be used to constrain S , further suggesting a median LGM surface cooling of −5.6°C. These results caution against the use of a fixed S under different climate background and have implications for paleotemperature reconstructions and climate projections.