This is the story of two papers. One paper, the 'natural gas is dirty' paper, came out in April. In it, several professors at Cornell University tried to quantify the threat that natural gas poses to the atmosphere.

“This is a really dirty fuel from a greenhouse gas standpoint,” said Bob Howarth, a professor of ecology at Cornell. He and his co-authors argue in their paper that natural gas is actually way dirtier than coal. That’s because of all the methane that leaks out during drilling, processing and storing natural gas. That’s a problem, because methane is much worse for the climate in the short term than carbon dioxide, the gas that results from burning coal.

“If one is concerned about global warming, we have got to do everything we can to reduce methane emissions," Howarth said. "I don’t think we should rely on coal either. We have to be serious about moving to truly renewable energies.”

Howarth’s 'natural gas is dirty' paper was published in a journal called Climatic Change, in a section reserved for new research meant to stir the pot. And stir the pot it definitely did. Now, the same journal plans to publish a study that directly disputes the 'natural gas is dirty' paper. This one is authored by another Cornell professor and argues that natural gas is clean.

So to sum up: two professors from the same school, writing for the same journal, having very different takes on how natural gas affects the climate.

“The point is the easy transition would be to simply encourage the substitution of gas for coal for electricity," said Larry Cathles, author of the second study, saying that 'natural gas is clean.' Among his arguments: the estimate in the 'natural gas is dirty' paper that up to 7.9 percent of gas leaks during production is way off base. “It’s a valuable commodity, there is absolutely no incentive to leak that much,” Cathles said.  

The Environmental Protection Agency has taken a similar position: since methane is the main ingredient in natural gas, it stands to reason that drillers would rather capture it than waste it.

Cathles says the 'natural gas is dirty' study is wrong in other ways too. He disagrees with the numbers the authors chose and how they weighted them. Another point: methane stays in the atmosphere for a much shorter time period than carbon dioxide, so even though its worse for the atmosphere, it has less time to do damage.

But another author of the April findings, Tony Ingraffea, says he stands behind their original findings. “Absolutely, no budge,” he said.  

Ingraffea is on leave from Cornell. He gives talks across upstate warning people that New York's  proposed hydrofracking regulations do very little about methane emissions. “Speaking as a professor, if I were to grade it A to F? F.”

But the larger issue here is whether or not science supports the commonly held belief that natural gas is a cleaner fuel. So far that open question hasn’t stopped the rise of natural gas. The U.S. Energy Information Administration expects a 16 percent increase in use in the next two decades or so. And the push is on to use it more for transportation. Congress is considering a bill to subsidize a network of natural gas filling stations. That bill already has 181 co-sponsors.

But all that is happening while the jury is still out on whether natural gas would actually offer a greener future.