An interhemispheric mechanism for glacial abrupt climate change

作者：Banderas Ruben^*; Alvarez Solas Jorge; Robinson Alexander; Montoya Marisa

来源：Climate Dynamics, 2015, 44(9-10): 2897-2908.

DOI：10.1007/s00382-014-2211-8

• Abrupt climate change
• Paleoclimate modeling
• Dansgaard-Oeschger events
• Atlantic meridional overturning circulation

The last glacial period was punctuated by abrupt climate changes that are widely considered to result from millennial-scale variability of the Atlantic meridional overturning circulation (AMOC). However, the origin of these AMOC reorganizations remains poorly understood. The climatic connection between both hemispheres indicated by proxies suggests that the Southern Ocean (SO) could regulate this variability through changes in winds and atmospheric CO2 concentration. Here, we investigate this hypothesis using a coupled climate model forced by prescribed CO2 and SO wind-stress variations. We find that the AMOC exhibits an oscillatory behavior between weak and strong circulation regimes which is ultimately caused by changes in the meridional density gradient of the Atlantic Ocean. The evolution of the simulated climatic patterns matches the amplitude and timing of the largest events that occurred during the last glacial period and their widespread climatic impacts. Our results suggest the existence of an internal interhemispheric oscillation mediated by the bipolar seesaw that could promote glacial abrupt climate changes through variations in atmospheric CO2 levels, the strength of the SO winds and AMOC reorganizations, and provide an explanation for the pervasive Antarctic-like climate signal found in proxy records worldwide.

• 出版日期2015-5