Last year, a scientist from Cornell University in Ithaca, New York published a paper in a scientific journal. The journal is called Climatic Change. Robert Howarth is the scientist who published the paper. He teaches environmental science at Cornell. He got the idea for the paper about three years ago. That's when the region around Ithaca was drawing interest from the oil and gas industry because it sits on top of the Marcellus shale, a vast deposit of natural gas.
"I was on sabbatical leave in France in the spring of 2009, and when I came home all of the sudden there are advertisements all over the place touting natural gas as a clean-burning fuel, a low-carbon footprint, good for the environment, good for global change," Howarth said.
The ads were correct, to a point: when you burn it, natural gas is the cleanest of the fossil fuels. So you would choose it over coal, for instance, because its carbon footprint is smaller. That's the idea, at least.
"The problem," Howarth said, "is that natural gas is methane. It's overwhelmingly methane, and methane is an extremely potent greenhouse gas."
Even small leaks could erode the greenhouse benefits of using natural gas. Howarth knew a lot about methane, having studied it as a grad student in the '70s, so with the prospect of the gas industry coming to his own back yard, he saw a research opportunity. He and his colleagues Renee Santoro and Tony Ingraffea cobbled together the few studies that existed and made some predictions.
"We concluded that shale gas has a very large greenhouse gas footprint," Howarth said.
So large, in fact, that it was actually worse than coal. Ingraffea, Howarth's co-author, is an engineer and outspoken critic of fracking. He says the public sees natural gas as a bridge fuel that will help us slowly lower our carbon footprint.
"What we're saying is — Bob, Renee and I, and a number of other scientists around the world — is that ain't true," Ingraffea said.
Part of their reasoning is that when a well is fracked, a large amount of gas comes right out of the ground. Sometimes that gas is vented to the atmosphere. The industry says this is rare, that usually drillers capture this or burn it off, which greatly reduces the methane content of its emissions. Howarth says he initially thought this was the case, but heard otherwise from industry insiders he talked to.
"So colleagues in the industry came back and said, 'Oh, no, no, no, it's a much bigger problem than you're estimating. It's not that the fluid comes up with methane dissolved in it and then it's released — it's these big burps of gas,'" Howarth said.
When it came out, the paper blew up in the media. Time Magazine even named Howarth and Ingraffea among its list of 100 most influential people in 2011. The oil and gas industry hated it, calling it "garbage science" in the press.
"I don't think we have to get into those adjectives, but in terms of, 'Is it a reflection of what goes in the real world?' I think it is not," said Howard Feldman of the American Petroleum Institute.
Feldman said the data Howarth used was based on EPA data that overstated emissions. His organization surveyed 90,000 wells recently and cut those estimates in half.
Scientists who study this issue were also leery about this paper, including Paulina Jaramillo of Carnegie Mellon University.
"Well, he said natural gas is worse than coal — that's a big statement," Jaramillo said.
Jaramillo is an expert on carbon footprint. She went back and studied the issue and found that even with high rates of methane leaking out, shale gas was still better than coal.
"All the studies I've seen say it's not true," Jaramillo said. "There's even a group at Cornell, from the geology department, I believe, that came out with a response to Howarth's paper.
"I felt that their conclusions were just completely wrong," said Larry Cathles, the author of what's been called the "other Cornell paper," in which he and several of his colleagues in the geology department defend natural gas.
"Is it as good as going to directly to a zero-carbon source?" Cathles said. "No, but it's 40% as good."
Half a greenhouse benefit is better than none at all. One bone of contention is how much gas is leaking out during fracking. Howarth estimates it's between three and a half and eight percent. Cathles thinks that's much too high.
"Are we leaking eight percent, nine percent?" Cathles said. "I don't think so, not even close. You've got companies that have a valuable product — they're not going to be losing ten percent of it."
Cathles and others have also criticized Howarth's use of a time scale. If you compare gas to coal over the short time scale, gas looks worse. That's because of a basic difference between the two greenhouse gases: carbon dioxide (CO2) and methane (CH4).
"When you stop burning fossil fuels, whenever that is, methane will come out of the atmosphere if it hasn't already very quickly, in a decade or so," said Cathles. "CO2 will not."
It will stay in the atmosphere for a century or more. But Howarth used both a 20-year and 100-year timescale because some scientists think we could soon reach a tipping point in global warming. They say at current rates, we could heat the earth enough to melt a vast store of methane frozen in the arctic within a few decades. So the damage done in the next few decades is crucial, Ingraffea says.
"We don't have 100 years to fix the problem," Ingraffea said. "We don't have 50 years to fix the problems. We have half a human generation, we have four presidential terms of office. Call it whatever you want, that's the amount of time we have to fix the problem."
There are other differences in the way these studies crunch the numbers, but there is something else that separates these two sides.
"I'd have to say that he's more of an advocate than really — you know, a scientist should be worried about getting to the bottom of the issue," Cathles said.
Cathles thinks Howarth cherry picked data to make gas out to be the bad guy. He points out Howarth's study was funded in part by the Park Foundation, which has supported anti-fracking groups.
Howarth and Ingraffea point out that Cathles has received money from the oil and gas industry for his research in the past, though not for this particular report. Ingraffea goes even farther.
"You should go back and ask Larry [Cathles] why he has credentials to be weighing in on this issue," Ingraffea said. "Or anybody else he who co-authored his paper with him. None of them have credentials on this problem. So they're pedestrians, arguing science."
Michael Oppenheimer the editor of Climatic Change, the journal where all these papers appeared, said the fact that Cathles is a geologist commenting on atmospheric science doesn't really matter.
"I don't care what Howarth or Cathles et al's credentials are, the important thing is what's in the writing," Oppenheimer said.
Complicating the matter, Cathles has an unorthodox view on climate change. Though he doesn't like the term, he's a climate skeptic.
"First of all, I'm a scientist, so I'm a skeptic on everything," he said. "Everything. Climate is no different."
Solar wind and the earth's orbit are some of the things Cathles thinks might be changing the climate, perhaps more than people. The vast majority of scientists disagree. They say we — people — are the climate changers.
Potential bias notwithstanding, the federal government is taking steps to make fracking better on greenhouse gases. By 2015, the EPA will require virtually all of the gas that comes out of the well — those big burps of gas — to be captured. Howarth says it's a great first step, but thinks other leaks will still make gas worse than coal, at least for these next few decades.
So, what will the impact of the fracking boom be on climate change? Robert Jackson, of Duke University, has studied the environmental impact of fracking. He's not sold on Howarth's argument, but he said that doesn't mean the paper is completely wrong, either.
"The real question is, how much better does it have to be to really be considered a bridge fuel, or how much better does it have to be to transform an energy infrastructure?" Jackson said. "If it's 10% better, all the sudden that's not so much a difference as if it's 50% better."
We won't really know the answer until we find out just how much gas escapes during fracking. More information on this is coming soon. The EPA is collecting data on methane emissions from fracking, and should release its results later in the year. Bob Howarth and Larry Cathles will be watching closely.