U.S. Cities Lose 20 Percent of Trees

Urban sprawl and highway construction have gobbled up greenery at a startling rate, leaving U.S. cities with 20 percent fewer trees than they had just 10 years ago, according to the environmental group American Forests. In a study released as part of the annual National Urban Forest conference, researchers used satellite images to look at the tree canopy in 448 urban areas. The loss was dramatic everywhere, but it was most acute in cities in the fast-growing Sunbelt. Atlanta, Ga., suffered the highest loss of trees, while Charlotte, N.C., and San Diego, Calif., were faring the best. Trees help preserve water, prevent flooding, cleanse the air of pollution, and reduce the need for air conditioning; their decreasing numbers are estimated to have cost the country $234 billion in environmental and health problems.