PARIS, April 25 -- Major economies are overstating how much carbon their forests can absorb in a climate accounting fudge that could allow them to use even more fossil fuels, new research said yesterday.

The assessment singled out Brazil and Australia, and warned a lack of rules around accounting for forests and other land-based carbon sinks meant countries could "game the system" when reporting their national greenhouse gas emissions.

Scientists are still unclear about how carbon sinks might behave as the planet warms in future, and exactly how much heat-trapping carbon dioxide they might soak up from the atmosphere.

But that has not stopped countries from making their own assumptions and using those numbers in their national climate ...