US academic study: gas benefits over coal may be offset by economics.

Environmental Science & Technology: “Implications of Shale Gas Development for Climate Change”, by Richard Newell and Daniel Raimi, is perhaps the first attempt at a comprehensive economic analysis that takes into account that abundant gas will lead to substitution for many energy sources, not just coal, and to increased energy demand.” “Its findings indicate that the benefit of substitution for coal may be entirely offset by these economic effects, depending in part on what actual amounts of methane releases are. It looks only at the US case, so does not get into issues of international trade.”