Meltwater Pulse 1A sea-level-rise patterns explained by global cascade of ice loss

Over the last deglaciation, global sea level rose by similar to 120-130 m, 10-20 m of which was attributed to a singular, catastrophic event known as Meltwater Pulse 1A (MWP-1A) that spanned at most 500 years approximately 14.6 kyr ago. Given data limitations and simplified models of Earth deformation, previous studies have struggled to determine the ice sources responsible for MWP-1A, its timing and, consequently, the impacts on global climate. With the expansion of palaeo sea-level records and growing consensus that more complex Earth deformation occurs over MWP-1A timescales, revisiting MWP-1A is timely. Here we resolve a sequence of ice loss over MWP-1A using a spatiotemporal sea-level fingerprinting approach constrained by temporal variations across sea-level data that fully models transient viscoelastic deformation, resulting in a space-time melt evolution. Our favoured sequence of ice sheet melting begins with the Laurentide contributing similar to 3 m (similar to 14.6-14.2 kyr ago), followed by Eurasia and West Antarctica contributing similar to 7 m and similar to 5 m, respectively (similar to 14.35-14.2 kyr ago). This scenario is consistent with proxy data that suggest a minimal Laurentide contribution and large retreat of the Eurasian Ice Sheet Complex. Our MWP-1A ice evolution demands the revision of global ice histories and illustrates deformation feedbacks that are relevant for modern ice collapse and sea-level rise.