This study investigates the mechanism driving Laurentide Ice-Sheet instabilities during Heinrich Events. Foraminifera-based subsurface ocean temperature and salinity reconstructions from the western subpolar North Atlantic reveal consistent rapid subsurface ocean warming preceding each Heinrich Event over the last 27,000 years. This supports the hypothesis that heat accumulation near the critical depth triggered melting of marine-terminating ice sheet portions, leading to Heinrich Events. The subsurface warming correlates with weakened Atlantic Meridional Overturning Circulation (AMOC), suggesting a precursor role for ocean circulation changes in initiating ice-sheet instabilities. Future AMOC weakening might cause accelerated subpolar Atlantic warming, impacting Arctic glacier stability and the North Atlantic freshwater budget.

Lars Max, Dirk Nürnberg, Cristiano M. Chiessi, Marlene M. Lenz, Stefan Mulitza