REUTERS OSLO RISING forest density in many countries is helping to offset climate change caused by deforestation from the Amazon basin to Indonesia, a study showed on Sunday.

The report indicated that the size of trees in a forest — rather than just the area covered — needed to be taken into account more in UN-led efforts to put a price on forests as part of a nascent market to slow global warming.

“Higher density means world forests are capturing more carbon,” experts in Finland and the United States said of the study in the online journal PLoS One, issued on June 5 which is World Environment Day in the UN calendar.

Trees soak up carbon dioxide, the main greenhouse gas, as they grow and release it when they burn or rot.

Deforestation in places from the Congo basin to Papua New Guinea is blamed for perhaps 12 to 20 percent of all emissions by human activities.

The report, based on a survey of 68 nations, found that the amount of carbon stored in forests increased in Europe and North America from 2000-10 despite little change in forest area.

And in Africa and South America, the total amount of carbon stored in forests fell at a slower rate than the loss of area, indicating that they had grown denser.

And some countries still had big losses of carbon, including Indonesia and Argentina.

The study did not try to estimate the overall trend, saying there was not yet enough data.

Greater density in some countries, including China, was probably linked to past forest plantings, lead author Aapo Rautiainen of the University of Helsinki told Reuters.