A new study published in The Proceedings of the National Academy of Sciences has found that forests in the eastern U.S. appear to be growing faster in response to rising levels of carbon dioxide in the atmosphere. The study centered mixed hardwoods representative of much of the those on the Eastern Seaboard. All are growing two to four times as fast as normal, according to a study. After controlling for other variables, scientists concluded that the change resulted largely from the increase in carbon dioxide, a major factor in climate change.