Are the global warming numbers cooked?

Here's one view of a small part of the puzzle....

The amount of carbon emissions caused by world forest destruction is likely far less than the 20 percent figure being widely used before global climate talks in December, said the head of the Brazilian institute that measures Amazon deforestation.

Gilberto Camara, the director of Brazil's respected National Institute for Space Research, said the 20 percent tally was based on poor science but that rich countries had no interest in questioning it because the number put more pressure on developing countries to stem greenhouse gases.

"I'm not in favor of conspiracy theories," Camara told Reuters in a telephone interview on Friday.

"But I should only state that the two people who like these figures are developed nations, who would like to overstress the contribution of developing nations to global carbon, and of course environmentalists."

A lower estimate for carbon emissions from deforestation would have an impact on the Copenhagen talks, where preserving forests is a top item on the agenda.

The summit will negotiate a follow-up to the Kyoto climate change treaty that could introduce forest credit trade to cut developing nation deforestation.

Camara, who stressed that he thought Brazil's deforestation rates remain too high, said recent calculations by his institute using detailed satellite data showed clearing of the world's biggest forest accounted for about 2.5 percent of annual global carbon emissions.

Given that the Amazon accounts for about a quarter of deforestation globally, a figure of about 10 percent for total emissions caused by forest destruction is likely to be more accurate, Camara said.