15 Sep 2011:
Evaporation from Trees
Helps Cool the Global Climate, Study Says
Water that evaporates from trees and forests not only has a significant local cooling effect, but also plays a role in cooling the global climate
, according to a new study by scientists at the Carnegie Institution's Global Ecology department. Reporting in the journal Environmental Research Letters,
the scientists found that evaporation from trees cooled the global climate by causing clouds to form low in the atmosphere, which reflects the sun’s rays back into space. Scientists have long known that evaporation had a local cooling effect, but have been unsure of the global effect of evaporation from trees, since water vapor also acts as a greenhouse gas in the atmosphere. But Carnegie scientists devised a climate model on the impact of tree evaporation showing that the overall global impact of evaporation is to stimulate the formation of more low-level clouds. This finding has important implications for land-use decision-making and underscores the importance of preserving forests and planting trees, the researchers said. “This shows us that the evaporation of water from trees and lakes in urban parks, like New York’s Central Park, not only help keep our cities cool, but also helps keep the whole planet cool,” said Carnegie atmospheric scientist Ken Caldeira
Yale Environment 360 is
a publication of the
Yale School of Forestry
& Environmental Studies
Yale Environment 360
articles are now available in Spanish and Portuguese on Universia
, the online educational network. Visit the site.
Business & Innovation
Policy & Politics
Pollution & Health
Science & Technology
Antarctica and the Arctic
Central & South America
A look at how acidifying oceans could threaten the Dungeness crab, one of the most valuable fisheries on the U.S. West Coast. Watch the video.
is now available for mobile devices at e360.yale.edu/mobile
An aerial view of why Europe’s per capita carbon emissions are less than 50 percent of those in the U.S. View the photos.
An indigenous tribe’s deadly fight to save its ancestral land in the Amazon rainforest from logging. Learn more.
video series looks at the staggering amount of food wasted in the U.S. – a problem with major human and environmental costs. Watch the video.
Residents of the Chocó Rainforest in Ecuador are choosing to plant cacao over logging in an effort to slow deforestation.
Watch the video.
Tribal people and ranchers join together to stop a project that would haul coal across their Montana land. Watch the video.