Les forêts primaires constituent un important puits de carbone[en] 

The international group of scientists' findings indicate that old-growth forests in the northern hemisphere account for at least 10% of global net uptake of carbon dioxide. This contrasts with the commonly accepted view that these forests are carbon neutral, a hypothesis based mainly on a single study from the 1960s.

The new research builds on 519 plot studies and shows that carbon accumulation continues in forests that are centuries old. Nevertheless, the Kyoto Protocol does not call for forests to be left intact, instead demanding changes to the carbon stock by afforestation, reforestation and deforestation.

Old-growth forests have been accumulating carbon for centuries, yet much of it will be lost to the atmosphere if disturbed, the study warned. The researchers therefore conclude that "the carbon-accounting rules for forests should give credit for leaving old-growth forest intact".

"If you are concerned about offsetting greenhouse gas emissions and look at old forests from nothing more than a carbon perspective, the best thing to do is leave them alone," said Professor Beverly Law, a co-author of the study.

Deforestation is widely considered to be a key driver of global warming as tropical and other forests absorb CO2, thus mitigating the effects of emissions on the climate. But EU policymakers are struggling to define rules to keep trees standing (EurActiv 11/09/08).