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Abstract

The Antarctic continental shelf plays a critical role in global climate system as a buffer zone of the heat and material exchange between Southern Ocean and Antarctica. To investigate the response of physical properties for Antarctic shelf waters in response to increasing atmospheric greenhouse gases, we present a comparison of a fully coupled global climate model, Community Earth System Model version 1.2.2, results between present-day climate run (PC, atmospheric CO₂ is fixed to 367 ppm) and future climate run (FC, atmospheric CO₂ is double to 734 ppm). The latter experiment was branched from 71 year of the control run for 140 years and was integrated for another 100 years. The last 20 years of both simulations were analyzed. The resulting physical properties of Antarctic shelf waters reproduced by PC are generally consistent with what has been known by previous studies except for the Prydz Bay where the considerably warm (T>0.5C) water was simulated and the Cape Darnley where the outflows of dense shelf water were vanished. The FC results demonstrate significant warming (T>0.5°C) on the shelves in Amundsen Sea, Bellingshausen Sea, and eastern Ross Sea, and off the Adelie and Budd coasts, and freshening all over the Antarctic shelves, suppressing the Antarctic bottom water formation. The results suggest weakening of deep and abyssal circulation by suppressed bottom water formation due to increased atmospheric CO₂ concentration along with the potential for more rapid melting of Antarctic ice sheets.