Margit Simon
Margit H. Simon is a senior researcher in the ocean observation group at the Norwegian Research Centre in Bergen, Norway affiliated with the Bjerknes Centre for Climate Research and Center for Early Sapiens Behaviour. A paleoceanographer and paleoclimatologist by training, a central focus of her research has been investigating ocean-cryosphere-atmosphere interactions in the northern North Atlantic and Nordic Seas during past abrupt climate changes, the Last Glacial Maximum and Holocene.
She explores these themes by using a range of sedimentary, paleoecological and geochemical proxies in marine sediment cores.
Since her PhD, she has intensively studied past climate variability in South Africa and its surrounding oceans. By bridging the gap between climate reconstructions and archaeological data, she has recently been awarded an ERC Consolidator Grant to investigate how environmental factors shaped the cultural evolution of early Homo sapiens in Africa, using cutting-edge analytical and computational approaches.
Nordic Sea convection led abrupt North Atlantic warm events during Dansgaard-Oeschger cycles
During the last glacial period changes in the strength of ocean convection in the high-northern latitudes contributed to abrupt global climate changes known as Dansgaard–Oeschger (DO) cycles. However, the lack of high-resolution empirical evidence has yet precluded inferring the physical coupling between ocean and atmosphere. We examined circulation changes in the southern Nordic Seas by reconstructing radiocarbon ventilation ages across four DO cycles in a marine sediment core hinging on a precise multi-tephra-based synchronization to Greenland ice cores. Sea ice retreat and changes in Nordic Sea convection were tightly coupled during Dansgaard-Oeschger warming events. Our results show that open ocean convection in the southern Nordic Seas resumed ahead of the abrupt air-temperature increases recorded in ice cores by ∼400 years (95% range: 50-660 years) and sea ice decline led Greenland climate change by ~100 years (95% range: 20-200 years). In contrast to the loss in sea ice in the south, the sea ice extent in the northern Nordic Seas increased during the same period. Thus, this suggests that the southern Nordic Seas, along with the North Atlantic, served as crucial regions where convection shifts and sea ice fluctuations played both a necessary and sufficient role in explaining the observed DO impacts in Greenland.
