In the words of Time, when selecting Howarth as one of the "People Who Mattered":
"Robert Howarth...who produced one of the most controversial scientific studies of the year; a paper arguing that natural gas produced by fracking may actually have a bigger greenhouse gas footprint than coal. The study--strenuously opposed by the gas industry and many of Howarth's fellow scientists--undercut shale gas's major claim as a clean fuel."
Time also named Anthony Ingraffea and Mark Ruffalo, as the people who mattered in the fracking debates, which Time declared to be the environmental issue of the year, eclipsing climate change.
Howarth and Ingraffea's study has been debunked by 6 or more studies, all finding that coal emits twice the carbon on a lifecycle basis, but the Howarth paper did matter. It has done major damage to the cause of reducing carbon pollution by so badly misleading millions of people around the world about the carbon impacts of using coal or gas.
On the bright side in the USA, natural gas displacing coal is one reason that US carbon emissions will fall in 2011 and probably again in 2012. But for shale gas that now supplies 34% of all USA gas, the price of gas would likely be over $8 per thousand cubic feet and uncompetitive with coal.
Had Howarth won a broad ban of shale gas, the result would have been devastating for consumers, and especially for low-income families, and the nation would be building more coal plants and not closing many of the 231 units now scheduled to end operation.
While Horwath mattered a lot in 2011, he was unable to prevent substantial carbon reductions resulting from replacing coal and oil with gas. Thank goodness for that.