The Max Planck Institute for Meteorology in Hamburg said computer models it had created showed the average global temperature could rise by as much as 4.1 Celsius by 2100, melting sea-ice in the Arctic. 

This May 13, 2001 file photo shows seals as they rest on ice at the White Sea coast, some 200 km north-east of Arkhangelsk. (REUTERS)

"Our research pointed to rapid global warming and the shifting of climate zones," said project leader Erich Roeckner. "Our climate models predict warmer and drier summers for Europe, with warmer and wetter winters." 

The German researchers said that polar bears may no longer be able to wander from one ice floe to the other in the Arctic, while ships may increasingly choose to navigate through northern passages around Siberia and Canada. 

The German study's release comes just days after U.S. scientists said the Arctic ice shelf had melted for the fourth straight year to its smallest area in a century, driven by rising temperatures. 

Most scientists believe greenhouse gases, including carbon dioxide that is released mainly from cars and utility smokestacks, cause global warming by trapping solar heat in the atmosphere. 

Guy Brasseur, director of the Max-Planck Institute for Meteorology, said the report aimed to provide politicians with the information they needed to make crucial decisions. 

The findings are to be included in a report by the Intergovernmental Panel on Climate Change (IPCC), a group of scientists that advises the United Nations. 

Brasseur told Reuters that Europe would suffer more summer droughts and storms. A general decrease in rainfall throughout southern Europe would have a dramatic impact on agriculture. 

Klaus Toepfer, head of the U.N. Environment Programme, said in an interview with German broadcasters NDR that he was extremely worried about the study's results and stressed the need for urgent action against climate change.