Despite unanswered questions about the environmental effects of drilling, the gas boom "is actually one of a number of reasons for cautious optimism," Mann said. "There's a lot of doom and gloom out there. It is important to point out that there is still time" to address global warning.
Associated Press writers Seth Borenstein in Washington and Jonathan Fahey in New York contributed to this story.
U.S. Energy Information Agency: http://bit.ly/MRLOFR
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