The BP Deepwater Horizon oil spill that shocked the world is fading into the background, but the effects of the disaster will long be felt. And now for the first time an independent study has confirmed the disastrous extent of the oil spill making it the largest marine oil accident ever.
“We wanted to do an independent estimate because people had the sense that the numbers out there were not necessarily accurate,” said lead author Timothy Crone, a marine geophysicist at Columbia University’s Lamont-Doherty Earth Observatory.
Using a new technique to measure the amount of oil that escaped by analysing the footage of it escaping from the pipe, the upper estimates of 56,000 to 68,000 barrels released daily have been confirmed.
After the explosion of the Deepwater Horizon oil rig, officials claimed that no estimate of the amount of oil being released into the Gulf of Mexico could be extracted. But public and scientific pressure forced their hands, and the first estimate given was that 1,000 barrels of oil was escaping into the water.
From there, the estimates grew; 5,000 a day from the National Oceanic and Atmospheric Administration, then 12,000 to 19,000 from the government, then continually upwards as the sheer extent of the spill became known.
There has been no transparency from the official estimates though; no information as to how those figures had been acquired, leading many to wonder.
This new study is the first to lay out the details of an analysis publically in a peer-reviewed paper.
The new study divided the flow of oil up into two periods; from April 22 to June 3, when oil was erupting from a jagged break in the riser; and June 3 to July 15, when the riser was cut and oil spewed into the ocean unimpeded to when the first effective cap was installed.
From the early period the flow of oil was about 56,000 barrels of oil a day, which went up to 68,000 barrels of oil a day when the pipe was cut. Subtracting 804,877 barrels of oil collected by BP at the site of the spill, the total of barrels that escaped into the ocean comes in at 4.4 million.
These figures are based on a new technique, developed by Crone, called optical plume velocimetry.
Crone started developing optical plume velocimetry in 2006, in order to study natural hydrothermal vents—volcanically driven cracks and holes in the seafloor that shoot out buoyant, superheated jets of mineral-laden water.
A jet from a leaking oil pipe is similar.
The technique uses high-resolution video from underwater cameras to track the motion of turbulent billows and flows in the water, breaking down the movement pixel by pixel. Under a grant from the U.S. National Science Foundation, Crone tested it first in the lab, then at deep-sea vents in the eastern Pacific, and the Juan de Fuca ridge, off the U.S. Pacific northwest. He is currently developing a network of automatic cameras that will track vent activity on the Juan de Fuca.
“This is a great example of how basic research that doesn’t seem to have any immediate value suddenly gains huge immediacy for society,” said Crone.
These figures are only a beginning though. “We clearly acknowledge the limits of our technique; we’re unlikely to ever know the exact figure,” Crone said.
“This is not the last word,” said Lamont marine geophysicist Maya Tolstoy and co-author with Crone. “It is the first peer-reviewed word. But we think it’s a really good ballpark.”
Source: The Earth Institute at Columbia University
Image Source: US Senate Committee on Environment and Public Works