U.S. Forests Soak Up Carbon Dioxide, But For How Long?: Scientific American

MISSOULA, Mont.—U.S. forests offset roughly 11 percent of the nation's industrial greenhouse gas emissions, storing "significant amounts" of carbon [dioxide] that would otherwise pollute the atmosphere, according to new government data.

The findings, released last week, estimate the nation's expanding forests sequester an additional 192 million metric tons of carbon annually due to increases in both the total area of forest land and the amount of carbon stored per acre.

That's the equivalent of removing about half the cars on the roads nationwide, or almost 135 million vehicles.
...
"Forest management on all lands can contribute significantly toward cooling a warming planet," U.S. Agriculture Secretary Tom Vilsack said in a statement. "This new information will assist the public and policy makers as we work to address this significant issue."