Towards a quantitative understanding of millennial-scale Antarctic Warming Events

• Main Authors: Axel Timmermann, Laurie Menviel, Yuko Okumura, Annalisa Schilla, Ute Merkel, Oliver Timm, Aixue Hu, Michael Schulz
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2010
• Subjects: Antarctic; Ross Sea; West Antarctic Ice Sheet; Pacific; Byrd; Marie Byrd Land; Antarc*; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.226.919; http://nldr.library.ucar.edu/repository/assets/osgc/fy10_201704.pdf

The interhemispheric temperature response to a meltwater-induced weakening of the Atlantic Meridional Overturning Circulation (AMOC) is characterized by a Northern Hemispheric cooling and a Southern Hemispheric warming. This so-called bipolar seesaw pattern explains many millennialscale features identified in paleo-proxy records from both hemispheres. Here we present modeling evidence that suggests that the Southern Hemispheric response to a weakening of the AMOC includes elements that have previously been overlooked. Under present-day conditions an AMOC weakening leads to an intensification of the negative phase of the Pacific South America (PSA) pattern with its southernmost pole north of the Ross Sea. An intensified PSA pattern may lead to a regional cooling of Marie Byrd Land, thereby favoring an in-phase temperature relationship between the Northern Hemisphere and the western side of the West Antarctic Ice Sheet on millennial timescales. However, under glacial conditions due to reduced