Rain Forests Absorb Carbon Dioxide From Burning Fuels

Scientists working in Brazil have found the first proof that undisturbed tropical rain forests soak up huge amounts of the carbon dioxide that people produce by burning fuels.

The measurements, published today in the journal Science, show the southwest portion of the Amazon rain forest absorbs a ton of carbon dioxide for every hectare of rain forest every year. A hectare is 2.47 acres.

“Virgin forest sequesters carbon from the atmosphere,” wrote John Grace of the University of Edinburgh, who led a team of ecologists from the United Kingdom, Australia and Brazil. “The whole of tropical South America may act as a carbon sink.”

Extend Grace’s measurements globally and the world’s remaining tracts of tropical rain forests could be absorbing a billion tons of carbon dioxide every year, fully one-sixth of the amount produced annually by burning fuels, said Pieter Tans of the National Oceanic and Atmospheric Administration.

The carbon dioxide content of the atmosphere has been rising slowly for decades, and today it is 30% higher than at the turn of the century, Tans said. Much of this increase is attributed to burning fuels and cutting down and burning forests.

Many scientists are convinced that increased carbon dioxide could cause a global temperature increase known as the greenhouse effect, in which the gas molecules prevent the sun’s heat from being reflected back into space. That could cause gradual changes in the climate, sea level and rainfall, which some experts believe already is occurring.

The oceans are the world’s largest absorber of excess carbon dioxide, and Tans discovered last summer that newly growing forests in the Northern Hemisphere also act as large carbon sinks. That’s because plants “breathe” carbon dioxide, using the gas to switch on the photosynthesis that lets them grow and multiply.