Advances in technology for extracting gas from shale and methane beds have quickened dramatically, altering the global balance of energy faster than almost anybody expected.

Tony Hayward, BP's chief executive, said proven natural gas reserves around the world have risen to 1.2 trillion barrels of oil equivalent, enough for 60 years' supply – and rising fast.

"There has been a revolution in the gas fields of North America. Reserve estimates are rising sharply as technology unlocks unconventional resources," he said.

This is almost unknown to the public, despite the efforts of Nick Grealy at "No Hot Air" who has been arguing for some time that Britain's shale reserves could replace declining North Sea output.

The breakthrough has been to combine 3-D seismic imaging with new technologies to free "tight gas" by smashing rocks, known as hydro-fracturing or "fracking" in the trade.

The US is leading the charge. Operations in Pennsylvania and Texas have already been sufficient to cut US imports of liquefied natural gas (LGN) from Trinidad and Qatar to almost nil, with knock-on effects for the global gas market – and crude oil.

Shale gas is undoubtedly messy. Millions of gallons of water mixed with sand, hydrochloric acid and toxic chemicals are blasted at rocks. This is supposed to happen below the water basins but accidents have been common. Pennsylvania's eco-police have shut down a Cabot Oil & Gas operation after 8,000 gallons of chemicals spilled into a stream.

Nor is it exactly green. Natural gas has much lower CO2 emissions than coal, even from shale – which is why the Sierra Club is backing it as the lesser of evils against "clean coal" (not yet a reality). The US Federal Energy Regulatory Commission said America may not need any new coal or nuclear plants "ever" again.