Forests -- Coming or going?

Data on tropical forest cover is so poor that we do not know if the forests are declining, a study has found.

Alan Grainger from the UK's University of Leeds examined UN analyses going back almost 30 years, and found that "evidence for a decline is unclear".

Dr Grainger is not so sure. "People have been assuming that forest cover is shrinking," he told BBC News, "and certainly deforestation has been taking place on a large scale."

But, he says, there is also evidence that in some countries, forests are expanding spontaneously.

"Our analysis does not prove that tropical forest decline is not happening, merely that it is is difficult to demonstrate it convincingly using available tropical forest area data," he writes in PNAS.

Basically, we don't know if there's a problem to fix.