Climate changes in the Atlantic sector of Antarctica over the past 500 years from ice-core and other evidence

Evidence from ice cores, borehole temperatures, early expeditions and glacier margins is used to identify the major climate trends of the past 500 years in the Antarctic Peninsula region. Apparent conflicts between the different data sources are exposed and causes discussed. Ice-core records from areas influenced by the Weddell Sea appear to be strongly sensitive to ice-edge effects, which can be detected in the profiles of deuterium excess and methane sulphonic acid. The various data now appear to be consistent with a scenario where conditions during the mid-19th century to 1940’s period was fairly cool until the onset of the recent extensive warming in the post-1940’s period. The coldest period of the past 300 years appears to have occurred around 1760–1780, associated with strong disturbances in the atmospheric circulation in the Weddell Sea region. This may be contemporaneous with a rather stronger cold anomaly previously observed at Law Dome and suggested for ice cores recovered elsewhere in East Antarctica

A 340 year record of biogenic sulphur from the Weddell Sea area, Antarctic

The high MSA (methanesulphonic acid) concentration reflects the proximity of the Weddell Sea, believed to be a region of high marine phytoplankton production. The overall mean nss-SO2-4 (non sea salt sulphate) concentration is about 66% of the total sulphate deposited in snowfall. Low-frequency variations of MSA and ozygen-isotope signals correlate closely, indicating that they may be modulated by similar atmospheric processes. Positive correlations are observed between the oxygen-isotope signature and both MSA and nss SO2-4. A small negative correlation can be seen between both species and the annual duration of sea ice at Scotia Bay, Laurie Island in the South Orkneys, since 1902. -from Author