The world’s worst ever oil spill is also the biggest methane leak in human history, US government scientists have said.
The US Geological Survey’s “flow team” has estimated between 4.5 billion to 9 billion cubic feet of natural gas have escaped from BP’s Deepwater Horizon rig since it exploded in April, Associated Press said on June 19.
John Kessler, an oceanographer at the Texas A&M University, told AP the leak was “the most vigorous methane eruption in modern human history”. Scientists think methane makes up 40% to 70% of what is spilling from the damaged BP rig.
Experts say the methane could worsen the already dire ecological impact of the oil spill, helping to create oxygen-poor dead zones that kill marine life.
The methane leak may also be a reason why vast plumes of oil have been found drifting deep underwater. Normally, oil would be expected to rise to the surface.
AP said a University of Georgia research team studied a 15-mile-long underwater oil plume in early June. The team “found methane concentrations up to 10,000 times higher than normal, and oxygen levels depleted by 40% or more”.
But BP has rejected claims that large amounts of methane are present in the Gulf. BP spokesman Mark Proegler told AP: “The gas that escapes, what we don't flare, goes up to the surface and is gone.”
Yet any methane that does reach the surface from this vast underwater leak will worsen global warming. Methane is a powerful greenhouse gas, about 70 times more potent than carbon-dioxide over a 20 year time-span.
BP has also faced new accusations that it has consistently lied about the extent of the gulf oil spill.
Reuters said on June 20 that Democrat representative Ed Markey had released an internal BP document revealing the company’s own worst-case estimate was that the leak “could be as high as 100,000 barrels per day”.
When the leak first took place, BP said the leak was about 1000 barrels a day. Later, it raised the estimate to 5000 barrels.
BP denied the internal document was relevant. “I don’t think there's been any underestimating”, a BP spokesperson told Reuters.
Yet on June 16, BP announced it intended to upgrade its capacity to collect oil in the gulf from its current 28,000 barrels a day to 80,000 barrels — 20,000 barrels more than it has publicly acknowledged is leaking.