Cold conditions in Antarctica during the Little Ice Age — Implications for abrupt climate change mechanisms

The Little Ice Age (LIA) is one of the most prominent climate shifts in the past 5000 yrs. It has been suggested that the LIA might be the most recent of the Dansgaard–Oeschger events, which are better known as abrupt, large scale climate oscillations during the last glacial period. If the case, then according to Broecker (2000a, 2000b) Antarctica should have warmed during the LIA, when the Northern Hemisphere was cold. Here we present new data from the Ross Sea, Antarctica, that indicates surface temperatures were ~ 2 °C colder during the LIA, with colder sea surface temperatures in the Southern Ocean and/or increased sea-ice extent, stronger katabatic winds, and decreased snow accumulation. Whilst we find there was large spatial and temporal variability, overall Antarctica was cooler and stormier during the LIA. Although temperatures have warmed since the termination of the LIA, atmospheric circulation strength has remained at the same, elevated level. We conclude, that the LIA was either caused by alternative forcings, or that the sea-saw mechanism operates differently during warm periods.

Research Highlights
► During the Little Ice Age Antarctica experienced overall cooler conditions.
► Antarctica was in phase with the Northern Hemisphere Little Ice Age event.
► Hence, the sea saw mechanism cannot explain this latest rapid climate change event.
► The thermohaline circulation is unlikely to have been the main driver.