Diatom based reconstruction of climate evolution through the Last Glacial Maximum to Holocene in the Cosmonaut Sea, East Antarctica

Diatom composition has been studied in two cores retrieved from the Cosmonaut Sea, East Antarctica, during the 36th Chinese Antarctic Research Expedition. The resulting diatom data are compared to other records from the Southern Ocean and the deglaciation history of the Antarctic ice sheet to reveal the climatic response of the ice-proximal environment to the melting of the ice sheet from the Last Glacial Maximum (LGM) to Holocene. The LGM is marked by low productivity and extensive sea ice cover that resulted in poor preservation of diatom frustules. The last deglacial warming process is facilitated by the “bipolar seesaw” effect. The environment in the Cosmonaut Sea is primarily influenced by the melting of the West Antarctic Ice Sheet (WAIS) during the last deglaciation, while the East Antarctic Ice Sheet (EAIS) remained relatively stable. Maximum sea ice retreat and southward intrusion of the warm Circumpolar Deep Water facilitate the melting of the EAIS during the early Holocene. The developing cavity under the WAIS is suggested to be responsible for the mid-late Holocene cooling in the Cosmonaut Sea. This indicates that the deglaciation of the WAIS is a primary control of environmental changes in the Cosmonaut Sea, despite its ice proximal location adjacent to the EAIS.