Abrupt Climate Change Linked To Ocean Current Circulationby Tommy on 27/08/2012
HUGE news for the lab this week – Our paper titled “Impact of abrupt deglacial climate change on Tropical Atlantic subsurface temperatures” was accepted for publication in Proceedings of the National Academy of Sciences (PNAS). The paper is authored by Dr. Matthew Schmidt, Dr. Ping Chang (TAMU Oceanography), Jennifer Hertzberg (Ph.D. student), Theodore Them (former M.S. student), Dr. Link Ji (TAMU Oceanography), and Dr. Bette Otto-Bliesner (NCAR). This paper represents a major step-forward in our understanding of abrupt climate change. GREAT work everyone! We will let you know when it is published so you can read it!
Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them II, Link Ja, and Bette L. Otto-Bliesner, PNAS Proceedings of the National Academy of Sciences of the United States of America, 1 August 2012
Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition.