In 2011, Howarth, Santoro, and Ingraffea published an estimated range of life-cycle methane emissions from development of natural gas, petroleum, and coal. They concluded that, even at the low end of their estimate, methane emissions from shale gas would make it the worst of the fossil fuels from a climate change point of view. They also concluded that their estimate was based on insufficient data and information because actual measurements of emissions on a national scale had never been done.

Others, including Cathles et al. at Cornell, disagreed, concluding that methane emissions were at levels where natural gas was the best of all fossil fuels from a climate change point of view. In the last 4 years many actual measurements of methane emissions have been made and new science on methane and climate change has been put forth.

Cathles and Ingraffea will review this evidence, reaching very different conclusions.