Reconstruction of modified Circumpolar Deep Water intrusion and its oceanographic impact in Prydz Bay, East Antarctica.

Oceanographic observations and models show that the heat brought by the warm modified Circumpolar Deep Water (mCDW) intrusion accelerates the melting of the Antarctic ice shelf and the loss of sea ice. Limited by the time scale of instrument recording, there are few records of mCDW intrusion into the East Antarctic continental shelf in the historical period. Here, we present a novel proxy of cadmium (Cd) concentrations in Adélie penguin feathers in an ornithogenic sediment profile to reconstruct the variability in mCDW intrusion into the continental shelf in Prydz Bay, East Antarctica, over the past 2500 years. Our reconstruction revealed that the intrusion of mCDW was enhanced from ∼1500 to 300 yr BP, stimulating the regional increase in glacier discharge and decrease in sea ice; at approximately 200 yr BP, mCDW intrusion weakened and then continued to enhance again during approximately the last 150 years. Furthermore, the enhancement of mCDW intrusion into Prydz Bay appeared to be driven by the southward shift and strengthening of the Southern Hemisphere Westerlies (SWW). The results implied that since this trend in SWW is forecasted for persisting into the 21st century, mCDW intrusion into Prydz Bay may increase continuously, threatening the stability of ice shelf and sea ice, and even the Antarctic Bottom Water formation in the future. [ABSTRACT FROM AUTHOR]