Scientists from Norfolk have sounded an alarm after spotting changes in the Earth's natural ability to absorb the greenhouse gas carbon dioxide.Oceans, trees and other plants have the ability to soak up carbon, acting as a large storage "sink" and absorbing about half of all human emissions.

Scientists from Norfolk have sounded an alarm after spotting changes in the Earth's natural ability to absorb the greenhouse gas carbon dioxide.

Oceans, trees and other plants have the ability to soak up carbon, acting as a large storage "sink" and absorbing about half of all human emissions.

But a four-year study by scientists from UEA, British Antarctic Survey (BAS) and the Max-Planck-Institute for Biogeochemistry reveals that an increase in winds over the Southern Ocean, caused by greenhouse gases and ozone depletion, has led to a release of stored CO2 into the atmosphere and is preventing further absorption of the gas.

Lead author Dr Corinne Le Quéré, of UEA and BAS, said: "This is the first time that we've been able to say that climate change itself is responsible for the saturation of the Southern Ocean sink.

"This is serious. All climate models predict that this kind of 'feedback' will continue and intensify during this century.

"The Earth's carbon sinks - of which the Southern Ocean accounts for 15pc - absorb about half of all human carbon emissions.

"With the Southern Ocean reaching its saturation point, more CO2 will stay in our atmosphere."

The new research, published yesterday in the journal Science, suggests that stabilisation of atmospheric CO2 is even more difficult to achieve than previously thought.

Additionally, acidification in the Southern Ocean is likely to reach dangerous levels earlier than the projected date of 2050.

Prof Chris Rapley, director of the British Antarctic Survey, said: "Since the beginning of the industrial revolution the world's oceans have absorbed about a quarter of the 500 gigatons (a gigaton is a billion tons) of carbon emitted into the atmosphere by humans. The possibility that in a warmer world the Southern Ocean - the strongest ocean sink - is weakening is a cause for concern."

The saturation of the Southern Ocean was revealed by scrutinising observations of atmospheric CO2 from 40 stations around the world.

Since 1981, the Southern Ocean sink ceased to increase, whereas CO2 emissions increased by 40pc.