"If we limit human activity in the tropical forests of the world, this could play a valuable role in helping to curb the rise in carbon dioxide in the atmosphere," says John Grace. (Credit: Lauria Jacques/Flickr)

carbon dioxide

Tropical trees absorb 2 billion tons of carbon yearly

Reducing deforestation in the tropics would significantly cut the amount of carbon dioxide emitted into the atmosphere by as much as one-fifth, research shows.

In the first study of its kind, scientists have calculated the amount of carbon absorbed by the world’s tropical forests and the amounts of greenhouse gas emissions created by loss of trees, as a result of human activity.

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Scientists analyzed data from previous studies, including satellite studies, to determine the amount of carbon absorbed and emitted by the world’s tropical forests in South and Central America, equatorial Africa, and Asia.

“Forest census data from an Amazon-wide network of forest plots, maintained by the Universities of Leeds and Oxford, played a critical part in the analysis,” says Professor Emanuel Gloor, a coauthor of the study from the School of Geography at the University of Leeds. The research appears in Global Change Biology.

Carbon storage

The researchers found that tropical forests absorb almost two billion tons of carbon each year, equivalent to one-fifth of the world’s carbon emissions, by storing it in their bark, leaves, and soil.

However, an equivalent amount is lost through logging, clearing of land for grazing, and growing biofuel crops such as palm oil, soy beans, and sugar. Peat fires in forests add significantly to the greenhouse gas emissions.

Researchers say emissions from tropical forests will increase as the climate warms, as rising temperatures accelerate the decay of dead plants and trees, giving off more carbon dioxide.

Global temperatures are forecast to rise by two degrees by the year 2099, which is predicted to increase annual carbon emissions from the forest by three-quarters of a billion tons.

“If we limit human activity in the tropical forests of the world, this could play a valuable role in helping to curb the rise in carbon dioxide in the atmosphere. Preventing further losses of carbon from our tropical forests must remain a high priority,” says Professor John Grace of the University of Edinburgh’s School of GeoSciences, who led the study.

The Natural Environment Research Council supported the study.

Source: University of Leeds

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