Princeton University researchers have uncovered a previously unknown,
 and possibly substantial, source of the greenhouse gas methane to the 
Earth's atmosphere.
After testing a sample of abandoned oil and natural gas wells in 
northwestern Pennsylvania, the researchers found that many of the old 
wells leaked substantial quantities of methane. Because there are so 
many abandoned wells nationwide (a recent study from Stanford University
 concluded there were roughly 3 million abandoned wells in the United 
States) the researchers believe the overall contribution of leaking 
wells could be significant... Read more
 

 
