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CO 2 ‐Induced Ocean Warming of the Antarctic Continental Shelf in an Eddying Global Climate Model
Author(s) -
Goddard Paul B.,
Dufour Carolina O.,
Yin Jianjun,
Griffies Stephen M.,
Winton Michael
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc012849
Subject(s) - continental shelf , geology , advection , ice shelf , oceanography , global warming , effects of global warming on oceans , antarctic bottom water , antarctic ice sheet , circumpolar deep water , climatology , sea ice , water mass , environmental science , climate change , north atlantic deep water , thermohaline circulation , cryosphere , physics , thermodynamics
Abstract Ocean warming near the Antarctic ice shelves has critical implications for future ice sheet mass loss and global sea level rise. A global climate model with an eddying ocean is used to quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized 2xCO 2 experiment. The results indicate that relatively large warm anomalies occur both in the upper 100 m and at depths above the shelf floor, which are controlled by different mechanisms. The near‐surface ocean warming is primarily a response to enhanced onshore advective heat transport across the shelf break. The deep shelf warming is initiated by onshore intrusions of relatively warm Circumpolar Deep Water (CDW), in density classes that access the shelf, as well as the reduction of the vertical mixing of heat. CO 2 ‐induced shelf freshening influences both warming mechanisms. The shelf freshening slows vertical mixing by limiting gravitational instabilities and the upward diffusion of heat associated with CDW, resulting in the buildup of heat at depth. Meanwhile, freshening near the shelf break enhances the lateral density gradient of the Antarctic Slope Front (ASF) and disconnect isopycnals between the shelf and CDW, making cross‐ASF heat exchange more difficult. However, at several locations along the ASF, the cross‐ASF heat transport is less inhibited and heat can move onshore. Once onshore, lateral and vertical heat advection work to disperse the heat anomalies across the shelf region. Understanding the inhomogeneous Antarctic shelf warming will lead to better projections of future ice sheet mass loss.