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FOREST LOCATION VITAL FOR GLOBAL WARMING

SARID, December 13, 2006

Tropical forests (22.5° north and south of the equator) may slow global warming more than temperate ones, says a French-US scientific report.

The study provides a holistic view of deforestation by examining the combined climate and carbon-cycle effects of large-scale deforestation in an interactive three-dimensional climate-carbon model.

“This is the first comprehensive assessment of the deforestation problem,” said Govindasamy Bala, an author of the research that will be presented on Dec. 15 at the American Geophysical Society annual meeting in San Francisco.

“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” Bala said.

However, the researchers found that planting trees between 30 and 50 degrees latitude worldwide increased the global mean surface air temperature by 0.7 degrees Fahrenheit. These temperate regions areas include the United States, Europe, most of the Middle East, northern China, Korea, and Japan.

"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," said Bala. "In fact, planting more trees in high latitudes could be counterproductive from a climate perspective."

For these regions, effective strategies to contain global warming should focus on energy efficiency and developing new sources of clean energy (such as solar and wind), the authors said.

In contrast, tropical forests help keep the Earth cool by not only absorbing carbon dioxide, but by evaporating plenty of water as well. Preserving them is a “win-win” situation,” they added.

Though tropical rain forests once formed a wide green belt around the equator, humans have reduced them by half over the last 200 years. Today, an estimated 93,000 square miles (150,000 square km) is destroyed yearly by logging, mining, and other industrial activities. These forests are found mostly in the Amazon River Basin, Congo River Basin, and Southeast Asia.

The study can be found online in the current issue of the journal "Geophysical Research Letters."(http://www.agu.org/pubs/crossref/2006.../2005GL025492.shtml).

Sources: Agencies, Bagheera (http://www.bagheera.com/inthewild/spot_sprain.htm).