"Our study shows that tropical forests are very beneficial to the climate because they take up carbon and increase cloudiness, which in turn helps cool the planet," said Govindasamy Bala, lead author of the research.

Planting forests north of the equator appeared to either "zero-out" or be counterproductive in regard to global warming, according to researchers.

Scientists from the French Universite' Montpellier II and the Carnegie Institution and Lawrence Livermore National Laboratory in the United States collaborated in the unprecedented study on the effects of deforestation on climate and atmospheric carbon.

Forests have been touted by environmentalists for their abilities to absorb carbon dioxide, a notorious greenhouse gas, and for exuding moisture that increases sun-blocking cloud cover.

Researchers involved in the study said the tendency for dark forest cover to absorb sunlight, thus warming the Earth, has been overlooked.

"The darkening of the surface by new forest canopies in the high-latitude Boreal regions allows absorption of more sunlight that helps to warm the surface," Bala said.

The study concluded that, by the year 2100, forests in mid- and high-latitudes will make some places up to 10 degrees Fahrenheit warmer than they would have been if the forests did not exist.

Planting forests in mid-latitude areas has been heavily promoted in the name of mitigating climate change caused by global warming, according to researchers.

The warmth from sunlight absorbed by forest canopies cancels out the positive effects from the trees taking in carbon, the study concluded.

"Our study shows that preserving and restoring forests is likely to be climatically ineffective as an approach to slow global warming," said study co-author Ken Caldeira of the Carnegie Institution.

"To prevent climate change, we need to transform our energy system. It is only by transforming our energy system and preserving natural habitat, such as forests, that we can maintain a healthy environment. We must focus on effective strategies and not just feel-good' strategies."

The research, billed as the first comprehensive assessment of the deforestation problem, will be presented on December 15 at an American Geophysical Society annual meeting in San Francisco.

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