Here is where I read about the carbon:
http://www.ncpa.org/ba/ba299.html
"Environmentalists also have argued that since the United States is the largest emitter of CO2, the greenhouse gas of primary concern, it should take the lead in reducing emissions of greenhouse gases. Unfortunately for their argument, it turns out that the U.S. is in fact a leading "air filter." According to an October 16, 1998, article in Science, North America removes more carbon (about 2 billion tons) from the atmosphere than it emits (1.5 billion tons) each year. One reason is the tremendous regrowth in the eastern U.S. of forests that act as carbon sinks, removing CO2 from the atmosphere."
Thanks again.
dave