Inverting the magnitude and sources of Meltwater Pulse 1A by fingerprinting sea-level constraints

Abstract:

Around 14,650 years ago, a rapid sea-level rise event-Meltwater Pulse 1A (MWP1A)-occurred, characterized by ~20 m global mean sea-level rise within 500 years. Ongoing uncertainty regarding the meltwater sources of this event limits our ability to understand the causality relationship between MWP-1A and concurrent ice-sheet instability and fast-changing climate. Here we present a new data-driven inversion approach, which, when combined with a glacio-isostatic adjustment model allow us to invert for the sources of MWP-1A using relative sea-level data from six geographically distributed site, including a key near-field site in Northwest Scotland. The 95% confidence range of our results suggests a minor Antarctic contribution of 0-5.2 m, a substantial Scandinavian contribution of 3.3-5.7 m, and a dominant North American contribution of 6.6-15.5 m with preferred values of 1.2, 3.5 and 13.2 m, respectively. We demonstrate that only a North American dominant scenario can successfully predict the observed pattern of sea-level variation at both far- and near-field sites. This inference is further supported by interpretation of Scottish isolation basin stratigraphy, which provides firm evidence to refute a dominant Antarctic contribution.