More trees won't solve climate problems

WASHINGTON, Nov. 17 (UPI) -- A U.S. report says planting more trees won't solve the problem of increasing carbon dioxide in the atmosphere.

The "State of the Carbon Cycle" report by U.S. Climate Change Science Program said that burning fossil fuel and clearing forests has significantly altered the global carbon cycle, and efforts to offset human-caused emissions by re-growing forests could create new sources of carbon in the future.

Chris Field of the Carnegie Institution's Department of Global Ecology said approximately 200 billion tons of carbon is hiding in carbon sinks created from planting forests on former farmland and adopting no-till agriculture.

"In effect, we have been getting a huge subsidy from these unmanaged parts of the carbon cycle," Field said Thursday in a release.

The report -- funded by the National Aeronautics and Space Administration, the U.S. Department of Energy, the National Oceanic and Atmospheric Administration and the National Science Foundation -- said the emission-reducing effects could reach their limit as forests mature and climate conditions change.