Bacteria ate nearly all the potentially climate-warming methane that spewed from BP's broken wellhead in the Gulf of Mexico last year, scientists reported yesterday.
Nearly 200,000 tonnes of methane -- more than any other single hydrocarbon emitted in the accident -- were released from the wellhead, and nearly all of it went into the deep water of the Gulf, researcher David Valentine of the University of California-Santa Barbara said.
Bacteria managed to take in the methane before it could rise from the sea bottom and be released into the atmosphere, but the process contributed to a loss of about 1 million tonnes of dissolved oxygen in areas southwest of the well.
That sounds like a lot of oxygen loss, but it was widely spread out, so that the bacterial munching did not contribute to a life-sapping low-oxygen condition known as hypoxia, said Mr Valentine, whose study was published in the journal 'Science'.
What happens to methane has been a key question for climate scientists, because methane is over 20 times more effective at trapping heat in the atmosphere than carbon dioxide.
For two months after the BP blowout on April 20, 2010, methane was not being consumed in and around the wellhead, leading some scientists to suspect it might linger in the water and eventually make its way into the air.
"If you have a very large release of methane like this, and it did make it into the atmosphere, that would be a problem," Mr Valentine said. "There have been a number of . . . large-scale methane releases in the past that have come from the ocean that have warmed the climate."
The US government filed a civil suit last month against BP and its partners for damage caused by the spill.