By Patrick Skahill
The latest national climate assessment says forests play a key role in keeping our air clean.
According to the report, America’s forests stored the equivalent of 11 percent of the country’s carbon dioxide emissions over a 25 year period. That’s because when trees breathe they suck up carbon dioxide, release oxygen, and store that leftover carbon in their trunks. But how scientists determine the amount of carbon stored in a tree is a question open for debate.