The team from Britain's National Soil Resources Institute at Cranfield University said its results implied a similar process would be under way in other temperate areas across the globe.

"Our findings suggest the soil part of the equation is scarier than we had thought," Professor Guy Kirk, of Cranfield University, told journalists at a science conference in Dublin. "The consequence is that there is more urgency about doing something."

Since the carbon appeared to be released from soil regardless of how the soil was used, they concluded that the main cause must be climate change itself.

Though they could not say where all the missing carbon had gone, much of it may be entering the atmosphere as the greenhouse gases carbon dioxide and methane, which scientists say has caused global warming.

KYOTO PROTOCOL

International efforts like the Kyoto protocol, which came into effect in February this year, have been aimed at stopping climate change by reducing the amount of greenhouse gases released into the atmosphere by industry.

But those efforts don't take into account carbon trapped in soil, about 300 times the amount released each year by burning fossil fuels.

In a separate article published alongside the paper in Nature, scientists from Germany's Max Planck Institute for Biogeochemistry said the carbon released from British soil wiped out the gains made by cutting its industrial emissions.

"These losses thus completely offset the past technological achievements in reducing CO2 emissions, putting the United Kingdom's success in reducing greenhouse-gas emissions in a different light," Detlef Schulze and Annette Freibauer wrote.

"An effective climate policy will require a more comprehensive approach," they wrote. "The scientific and political implications of the new findings are considerable."