Data from nine research stations were used in the studyWinter air temperatures over Antarctica have risen by more than 2C in the last 30 years, a new study shows.

Research published in the US journal Science says the warming is seen across the whole of the continent and much of the Southern Ocean.

The study questions the reliability of current climate models that fail to simulate the temperature rise.

In addition, the scientists from the British Antarctic Survey (BAS) say the cause of the warming is not clear.

It could be linked to increases in greenhouse gases in the atmosphere or natural variations in Antarctica's climate system.

Scientists are keen to understand the change in temperatures over the continent as the region holds enough water in its ice to raise sea levels by 60 metres.

Temperature rise

Temperature rises on parts of the surface of Antarctica have been seen for some time. The western side of the Antarctic Peninsula is known to have the largest annual warming seen anywhere in the world with increases of over 2.5C in the last 50 years.

Until now, very little was known about air temperatures above the vast continent.

The new work uses meteorological data collected from weather balloons launched in the Antarctic winters between 1971 and 2003. The scientists collected information from nine international research stations, mostly in the east of the continent.