Climate records from Greenland and Antarctic ice cores might reveal differences in their climatic models, but Arctic and Antarctic climate patterns are directly linked.

Recent research on the Antarctic ice core points to the fact that both hemispheres are binded by a 'bipolar seesaw.' Even short and weak temperature shifts in Antarctica influences northern temperature by a change of currents in the Atlantic Ocean.

Antarctica warmed several times from 55,000 to 20,000 years ago, whilst the North was under a glaciation and influx of warm water from the southern ocean. Vice versa, Antarctic temperatures dropped every time warmer water flew into the North Atlantic during warm interglacials. This indicates a global link between long-term climate shifts in both hemispheres via this 'bipolar seesaw' due to Atlantic Meridional Overturning Circulation changes. The Atlantic circulation is of huge concern in the global warming, because melted water from the icecap can slow the Atlantic currents.

The study was made by a team made by scientists from 10 European nations (Belgium, Denmark, France, Germany, UK, Italy, the Netherlands, Norway, Sweden and Switzerland) working in the European Project for Ice Coring in Antarctica (EPICA) with its campsite in Maud Land. The team measured methane concentrations from ice trapped air bubbles to assess climate. The new location allowed higher resolution atmospheric and climate records reconstruction due to its higher snow accumulation rate compared to the East Antarctic plateau.

The Greenland ice core analyses were made on the North Greenland Ice core Project (NGRIP). The new synchronized time scale enabled the scientists to directly compare high resolution temperature records from North Pole and South Pole. This uncovered the Bipolar Seesaw that actioned throughout and beyond the last glacial era. "It is really astounding" says paleoclimatologist Dr. Hubertus Fischer from the Alfred-Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven, "how systematic this process worked also for smaller temperature changes in the Antarctic. Our data shows that the degree of warming in the South is linearly related to the duration of cold periods in the North Atlantic."

"It is one of our goals in our new Centre for Interglacial Climate to investigate the importance of this Bipolar Seasaw in our present warm climate", says the Danish researchers from the Ice and Climate group at the Niels Bohr Institute, University of Copenhagen.

"This study is a good example for scientist from different disciplines of ice core research collaborating internationally. Ocean modeler, isotope specialists and glaciologists are bringing together their expertise," says Prof. Dr Heinz Miller, scientific leader of EPICA.