Instability of the Atlantic overturning circulation during Marine Isotope Stage 3. Issue 12 (20th June 2014)

• Record Type: Journal Article
• Authors: Zhang, Xiao; Prange, Matthias; Merkel, Ute; Schulz, Michael
• Is Part Of: Geophysical research letters. Volume 41:Issue 12(2014:Jun.)
• Page Start: 4285
• Page End: 4293
• Publication Date: 2014-06-20
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2014GL060321
• Languages: English
• ISSNs: 0094-8276

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Variations in the strength of the Atlantic meridional overturning circulation (AMOC) were involved in the occurrences of Dansgaard‐Oeschger (D‐O) events during Marine Isotope Stage 3 (MIS3). The stability of the AMOC to North Atlantic freshwater perturbations is studied using a comprehensive climate model under MIS3 boundary conditions. An AMOC stability diagram constructed from a series of equilibrium freshwater perturbation experiments reveals a highly nonlinear dependence of AMOC strength on freshwater forcing. The MIS3 baseline state is remarkably unstable with respect to minor perturbations. The global climate signal associated with a change in AMOC strength is consistent with a transition from an interstadial to a stadial state including an annual mean surface air temperature drop of ~8 K in central Greenland. We suggest that minor freshwater perturbations in the hydrologic cycle, e.g., related to ice sheet processes, had the potential to trigger D‐O‐type climate shifts associated with a threshold in the atmosphere‐ocean system.</p> </abstract>