Response of the thermohaline circulation during different pathways toward greenhouse gas stabilization

• Other Authors: Bryan, Frank (author), Nakashiki, Norikazu (author), Yoshida, Y. (author), Maruyama, K. (author), Schmittner, Andreas (editor), Chiang, John (editor), Hemmings, Sidney (editor)
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2007
• Subjects: Environmental sciences; Earth sciences; MOC; Achilles Heel; North Atlantic
• Online Access: http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-004-181; https://doi.org/10.1029/173GM01

It has been called the "Achilles heel" of our climate system: oceanographers revel in its complexity, and climatologists are impressed by its variability. Hollywood has even made a movie of it--"The Day After Tomorrow" (2004; 20th Century Fox). Hyperbole aside, no one denies the crucial importance of the ocean's meridional overturning circulation. In the mean, it transports and redistributes vast quantities of mass, heat, salt, carbon, nutrients and other substances around the globe. However, it is the variations to this circulation and their impact on the global climate that generate awe and instill worry. We know it can change rapidly (in as fast as a few years) with drastic consequences to climate: it did so many times in the past. Paleoproxy studies document abrupt changes of this circulation, affecting climate and biogeochemical systems particularly in the North Atlantic but also globally through communication via the atmosphere and ocean. This raises the question of whether future climatic changes associated with anthropogenic greenhouse gas emissions can trigger such a change, with damaging consequences to society and ecosystems. This monograph presents an overview of the current knowledge of the ocean's overturning circulation system, its changes and their global impacts. It combines studies of observations, theory and models and includes variability on all time scales, from sub-decadal to centennial variations in the recent past, to inferred variability on millennial and longer time scales during the last ice age, as well as projected changes under future climate warming scenarios. Also central to the theme of this monograph are the impacts of overturning circulation changes on climate and biogeochemical cycles. The idea for this monograph originated from two complementary special sessions organized by the editors and their collaborators in the Fall 2005 meeting of the American Geophysical Union in San Francisco: "OS33D: Past and Future Changes of Thermohaline Circulation" focused on changes and causal ...