Cornell professors Robert Howarth and Anthony Ingraffea started a controversy when they published a paper titled, Climate Impacts of Shale Gas Development in April 2011 that claimed that shale gas is dirtier than coal because of methane’s  short-term climate change threat.

Their findings were refuted by fellow Cornell researchers headed by Larry Cathles, an Earth scientist who faulted the methods used by Howarth and Ingraffea in their study.  The Cathles critique says Howarth and Ingraffea’s findings depend on exaggerated effects and amounts of methane that drillers allow to leak from wells.

Howarth and Ingraffea have released a follow-up response to this criticism which defends their study and says that methane emissions threaten to push climate effects past “potentially catastrophic tipping points” in the next 20 years.  This view is widely supported by other scientists who see methane as a dangerous global climate change gas (20 times more climate forcing than CO2).  In February 2012 a new study found that wells that pump natural gas from the ground in Colorado have leaked about twice as much gas into the atmosphere as previously thought.

Hal Harvey, an independent energy expert says, “generating a kilowatt-hour’s worth of electricity with a natural gas turbine emits only about half as much CO2 as from a coal plant…but one molecule of leaked gas contributes as much to global warming as 25 molecules of burned gas. That means that if the system for the exploration, extraction, compression, piping and burning of natural gas leaks by even 2.5 percent, it is as bad as coal.”  The climate forcing elements of leaked methane gas are very troubling.