Even if climate records from Greenland and Antarctic ice cores look different, climate of Artic and Antarctic are directly linked. Investigations of an Antarctic ice core indicate a principle connection between both hemispheres by a 'bipolar seesaw'. Even shorter and weaker temperature changes in the south are connected to fast changes in temperature in the north by change of ocean currents in the Atlantic ocean. Antarctica always warmed in the time period 10,000 to 55,000 years BP whilst the North remained cold. Concurrently, warm water export from the Southern Ocean to the North Atlantic was reduced. In contrast, the Antarctic started to cool every time more warm water started to flow into the North Atlantic during warm events in the north. This result suggests a general link between long-term climate changes in both hemispheres via this Bipolar Seesaw as a result of Atlantic Meridional Overturning Circulation changes. The Atlantic circulation is an important issue in the global warming debate, as icecap melt water can weaken the Atlantic currents.
The research project:
In the current issue of Nature, a joint effort of scientists from 10 European nations working together in the European Project for Ice Coring in Antarctica (EPICA) established a precise link between climate records from Greenland and Antarctica using data on global changes in methane concentrations derived from trapped air bubbles in the ice. The Antarctic ice core analyses were performed on the new EDML (EPICA Dronning Maude Land) ice core, which due to its higher snow accumulation rate allows for reconstruction of higher resolution atmospheric and climate records than previous ice cores from the East Antarctic plateau; a prerequisite for precise synchronisation with the Greenland counterpart. The Greenland ice core analyses were performed on the North Greenland Ice core Project (NGRIP). Based on the new synchronized time scale the scientists were able to c
Contact: Anne Dorte Bach
University of Copenhagen