Shale gas—an “unconventional” source of methane, like coal-bed gas (in coal seams) and tight gas (trapped in rock formations)—has rapidly transformed America’s energy outlook. At the same time discoveries of vast reserves of conventional gas from traditional wells have pushed up known reserves around the world. Gas is the only fossil fuel set to increase its share of energy demand in the years to come. …

Global reserves have been steadily increasing for at least 30 years. According to a report from the Massachusetts Institute of Technology (MIT), published last year, world production has grown significantly too, rising by two-fifths between 1990 and 2009, twice as fast as that of oil. Only half a decade ago it looked as though the world might have only 50 or 60 years-worth of gas. Now shale and other unconventional as well as new conventional gas finds have increased that period to 200 years or more, by some estimates. …

Not only have breakthroughs in technology opened up America’s shale beds, but advances in drilling in very deep water have dramatically changed exploration in the sea. Australia will emerge as a gas superpower as it begins to deliver large quantities of LNG from offshore fields. And better technology and global warming is unlocking the Arctic’s natural bounty.