Abstract
During the last deglaciation, sea levels rose as ice sheets retreated. This climate transition was punctuated by periods of more intense melting; the largest and most rapid of these – Meltwater Pulse 1A – occurred about 14,500 years ago, with rates of sea level rise reaching approximately 4 m per century1-3. Such rates of rise suggest ice-sheet instability, but the meltwater sources are poorly constrained, thus limiting our understanding of the causes and impacts of the event4-7. In particular, geophysical modelling studies constrained by tropical sea-level records1,8,9 suggest an Antarctic contribution of more than seven meters, whereas most reconstructions from Antarctica indicate no substantial change in ice-sheet volume around the time of Meltwater Pulse 1A10. Here we use a glacial isostatic adjustment model to reinterpret tropical sea level reconstructions from Barbados2, the Sunda Shelf3 and Tahiti1. According to our results, global mean sea level rise during Meltwater Pulse 1A was between 8.6 and 14.6 metres (95% probability). As for the melt partitioning, we find an allowable contribution from Antarctica of either 4.1 to 10.0 m or 0 to 6.9 m (95% probability), using two recent estimates11,12 of the contribution from the North American ice sheets. We conclude that a significant contribution of melt from the Antarctic ice sheets is not necessarily required to explain the documented sea level rise during Meltwater Pulse 1A.