It is commonly understood that the GHG emissions from gas-fired electricity generation are expected to be about half those of coal-fired generation. However, new research on methane leakage rates in the gas supply industry have put this assertion into question. We examine the research around this debate and the potential impacts on global warming of a wholesale transition from coal to gas in the light of these new findings. Finally, we examine the application of such a switch to the U.K. electricity sector and contrast this with alternative strategies that the UK might employ to meet its Climate Change Act goals of an 80% reduction in emissions by 2050.