Domestic shale gas has transformed the US energy equation, but its development can have unacceptable impacts on air and water quality, while methane emissions from oil and gas development can undo the climate benefit of burning natural gas instead of other fossil fuels. Colorado has led the way with the nation's strongest air pollution standards for oil and gas development, including the first direct regulation of methane. Governor John Hickenlooper and Environmental Defense Fund President Fred Krupp, who worked closely on the breakthrough rules in Colorado, lead a discussion of the way forward for shale gas. Fred Krupp, John Hickenlooper, Gillian Tett