Ice-shelf collapse from subsurface warming as a trigger for Heinrich events.

Abstract

Episodic iceberg-discharge events from the Hudson Strait Ice Stream (HSIS) of the Laurentide Ice Sheet, referred to as Heinrich events, are commonly attributed to internal ice-sheet instabilities, but their systematic occurrence at the culmination of a large reduction in the Atlantic meridional overturning circulation (AMOC) indicates a climate control. We report Mg/Ca data on benthic foraminifera from an intermediate-depth site in the northwest Atlantic and results from a climate-model simulation that reveal basin-wide subsurface warming at the same time as large reductions in the AMOC, with temperature increasing by approximately 2 °C over a 1-2 kyr interval prior to a Heinrich event. In simulations with an ocean model coupled to a thermodynamically active ice shelf, the increase in subsurface temperature increases basal melt rate under an ice shelf fronting the HSIS by a factor of approximately 6. By analogy with recent observations in Antarctica, the resulting ice-shelf loss and attendant HSIS acceleration would produce a Heinrich event.

DOI: 10.1073/pnas.1104772108

3 Figures and Tables

Showing 1-10 of 42 references

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage

  • M Gutjahr, Baa Hoogakker, M Frank, In Mccave
  • 2010

Consistent dating for Antarctic and Greenland ice cores

  • B Lemieux-Dudon
  • 2010

Deep sea corals off Brazil verify a poorly ventilated Southern Pacific Ocean during H2, H1 and the Younger Dryas

  • A Mangini
  • 2010

Transient simulation of last deglaciation with a new mechanism for Bølling-Allerød warming

  • Z Liu
  • 2009

Seawater carbonate ion-δ 13 C systematics and application to glacial-interglacial North Atlantic ocean circulation

  • J Yu, H Elderfield, Am Pitrowski
  • 2008

Mechanisms for an ∼7-kyrs climate and sea-level oscillation during Marine Isotope Stage 3. Ocean Circulation: Mechanisms and Impacts—Past and Future Changes of Meridional Overturning

  • Pu Clark, Sw Hostetler, Ng Pisias, A Schmittner, Kj Meissner
  • 2007

Calibrations for benthic foraminiferal Mg∕Ca paleothermometry and the carbonate ion hypothesis

  • H Elderfield, J Yu, P Anand, K Kiefer, B Nyland
  • 2006
Showing 1-10 of 18 extracted citations

Statistics

0102030201220132014201520162017
Citations per Year

52 Citations

Semantic Scholar estimates that this publication has received between 19 and 128 citations based on the available data.

See our FAQ for additional information.