ORESTS and farmlands cannot be relied on to soak up environmentally damaging green house gases, and cuts in emissions are the only long- term way to reduce global warming, scientists said

A new report by Britain's Royal society said too little is known about how much farmlands and forests, so called carbon sinks, can absorb carbon dioxide, the main greenhouse gas, from the atmosphere.

Carbon sinks will be major issue in Bonn next week when environmentalists and policy makers resume international climate talks, which have been jeopardized by the withdrawal of the US from the Kyoto agreement on global warning.

In its report, the independent body of top scientists said better methods are needed to verify the impact of carbon sinks on global warming . Reducing the amount of carbon dioxide from burning fossil fuels should be the main way to reduce global warming.

"These carbon sinks are of rather limited size and also will only work for a relatively short duration, a few decades. That means they cannot make a major contribution to reducing carbon emissions and solving the global warming problem" said professor john Shepherd, and author of the report.

Carbon sinks and emissions trading essentially a market for buying and selling the right to pollute , were the main stumbling blocks at the failed UN conference on climate change in the huge lat year

The US, Japan, Canada and Australia wanted more emphasis on carbon sinks in achieving the carbondioxide emission cuts set in the 1997 Kyoto protocol on global warming. The pact commits developed nations to cutting emissions of carbon dioxide by an average of just over 5 percent from 1990 levels by 2012.

Officials gathering in Bonn on July 16 for two weeks will try to get the talks back on track, despite the withdrawl of the us earlier this year.

Shepherd, the director Britian's Tyndall center for climate research, said carbon sinks were diverting the talks from the main issue which is cutting emissions

According to the report, carbon sinks and soil absorb about b 40 percent of carbon dioxide emissions and could soak up as much as 45 percent . But it added that the maximum that could be absorbed would only be equivalent to a quarter of that needed by 2050 to prevent major rises in global temperature.

" our view is that the argument is being diverted into what is really a rather unproductive area and people should get back to talking about carbon emission reductions at source by use of renewable (fuels) and whatever else they think is necessary." Said shepherd.

The scientists also warned that in future carbon sinks could become a source of carbon dioxide. They could release green house gases , such as methane

"The primary benefit of land carbon sinks is that they can be effective immediately and provide a financial incentive for the preservation and sustainable use of forests and agriculture land ," the report said

But the long term solution must cuts in carbon dioxide emissions through energy saving and replacing fossil fuels with renewable and nuclear energy.