School Notes: School of the Environment
January/February 2012

Deforestation causes cooling in northern latitudes

Deforestation, considered by scientists to contribute significantly to global warming, has been shown by a Yale-led team to actually cool the local climate in northern latitudes, according to a paper published in November in Nature. “If you cut trees in the boreal region, north of 45 degrees latitude, you have a net cooling effect,” said Xuhui Lee, professor of meteorology and the study’s principal investigator. “You release carbon into the atmosphere by cutting down trees, but you increase the albedo effect—the reflection of sunlight.” Lee and a team of researchers from 20 other institutions found that surface temperatures in open areas were cooler because snow cover reflected the sun’s rays back into outer space, while nearby forested areas absorbed the sun’s heat.

US rivers and streams full of carbon

Rivers and streams in the United States are releasing enough carbon into the atmosphere to fuel 3.4 million car trips to the moon, according to Yale researchers in Nature Geoscience. Their findings could change the way scientists model the movement of carbon between land, water, and the atmosphere. David Butman, a doctoral student and coauthor of a study with Pete Raymond, professor of ecosystem ecology, says that rivers “are a source of CO2, just like we breathe CO2 and smokestacks emit CO2, and this has never been systematically estimated from a region as large as the United States.” The researchers assert that a significant amount of carbon contained in land, which first is absorbed by plants and forests through the air, is leaking into streams and rivers and then releasing into the atmosphere before reaching coastal waterways. This release of carbon, said Butman, is the same as a car burning 40 billion gallons of gasoline.

Grant to support reforestation efforts

A Yale program that aims to restore tropical forests and the livelihoods that depend on them has received a six-year, $5.5 million grant from the Arcadia Fund to continue its work in Latin America and Southeast Asia. The Environmental Leadership & Training Initiative(ELTI) for Biodiversity Conservation in Tropical Forest Regions trains environmental managers and local decision-makers to support conservation efforts where forests have been cleared and exploited in Borneo, Brazil, Colombia, Panama, the Philippines, and Sumatra.