So How Big Was the BP Oil Spill?

Fire boat response crews battle the blazing remnants of the off shore oil rig Deepwater Horizon April 21, 2010. A Coast Guard MH-65C dolphin rescue helicopter and crew document the fire aboard the mobile offshore drilling unit Deepwater Horizon, while searching for survivors April 21, 2010. Multiple Coast Guard helicopters, planes and cutters responded to rescue the Deepwater Horizon's 126 person crew.

Photo: U.S. Coast Guard

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More than 127 million gallons.

That's how much BP oil spilled into the Gulf of Mexico, give or take 13 million gallons or so, according to the latest, and most definitive, government estimate of BP's massive Gulf oil spill. BP managed to capture another 24.8 million gallons of oil from its gushing well before finally fitting it with a temporary cap, 87 days after it began leaking following the April 20 explosion of the Deepwater Horizon rig.

Update: An independent analysis released Sept. 21 puts the total spilled at 185 million gallons (4.4 million barrels), plus another 33.8 million gallons that BP captured. The study has a 20% margin of error, so it is quite close to the latest government estimate, even though it puts the most likely total spilled about 10% higher.

That makes the spill the largest accidental oil spill in world history, and about three-times the size of the 1989 Exxon Valdez spill (30-35 million gallons of oil), which had been considered the largest in U.S. history before BP's Gulf oil spill. (Yes, that's more than the 11 million gallons typically quoted, and even the enormous 180 million gallons quoted above should be taken with a big grain of salt; if history is any guide, it's most likely a low-end estimate.)

Hundreds of miles of shoreline are oiled; tens of thousands of square miles of Gulf waters remain closed to fishing; thousands of birds, fish, turtles and marine mammals have died, millions of gallons of chemical dispersant were used deep underwater, and the ecosystem could remain contaminated in unpredictable ways for years or decades to come. Others are predicting a quick recovery, though; only time will tell.

If 152 million gallons of leaked oil (including the fraction captured by BP before it spilled into the Gulf) proves to be the right figure, the BP oil spill ranks as the second-worst in world history, behind just Saddam Hussein's Kuwait oil fires, which released as much as 336 million gallons in the Persian Gulf. Because Hussein deliberately set those fires, the BP oil spill is considered the worst accidental oil spill in world history.

There's no assurance that the cap BP placed on its well will hold permanently. It looks good, according to press reports and government statements, and that's encouraging. But a hurricane, a real possibility, could still disrupt the recovery effort before BP attempts the "static kill" procedure by connecting one or more relief wells to the leaking well. (Update: BP began its static kill Aug. 3.) Fortunately, Tropical Storm Colin, the latest tropical storm to form in the Atlantic this hurricane season, is likely to miss the Gulf of Mexico, according to the latest projections; still, even Hurricane Alex, which was hundreds of miles from the oil recovery effort, and Tropical Storm Bonnie and an unnamed tropical depression also set back recovery efforts, despite their distance from the spill site.

The (hopefully) final total spilled is all the more striking because BP and the government initially claimed just 1,000 barrels a day were leaking from its ruptured oil well at the bottom of the Gulf of Mexico, 50 miles off shore, where the Deepwater Horizon rig exploded spectacularly April 20, starting the historic BP oil spill. Later, with Obama Administration officials concurring, the estimate was upped to 5,000 barrels a day, though soon independent experts would say that that figure was 5-10 times short of the true rate. It appears that it was nearly 10 times shy of the actual rate, and that the initial estimate was as much as 60 times shy of the actual rate. There's so much oil leaking that the standard reference in these situations no longer applies: It only takes 640,000 gallons to fill an Olympic-sized swimming pool, but there's as much as 2.5 million gallons leaking every day (or as few as 1.5 million gallons).

Part of the reason the spill's size was so badly underestimated was that much of the oil will never reach the surface; it billowed out in huge plumes hundreds of miles long, but deep underwater. Another reason is that BP, with the federal okay (at least from the Coast Guard, if not the Environmental Protection Agency), sprayed dispersant deep underwater, diluting the oil at its source and reducing its apparent (but not its actual) size, or necessarily its toxicity. Finally, BP refused for weeks to release video footage of the spill, and then refused for more weeks to release high-definition footage that helped scientists estimate the flow more accurately.

Size matters. BP, one of the world's richest companies, will be charged penalties per barrel. The Exxon Valdez still hasn't been fully "cleaned up" nor have affected fishermen and residents of Alaska been fully compensated. And the Gulf of Mexico is only slightly less ecologically sensitive (warmer waters will help break up the oil faster) and equally if not more environmentally important: seafood, fish, marine mammals, sea turtles and birds, by the millions are threatened.

Unfortunately, an energy bill that might have moved the U.S. away from its oil dependence has stalled permanently in the Senate. A bill more narrowly focused on offshore oil drilling, but without robust provisions for global warming mitigation or renewable energy development, remains up for debate.

Environmental groups and their political allies are trying to generate enough outrage to seriously slow or stop offshore oil development, but even the supposed Gulf of Mexico offshore oil moratorium was a myth, so it's hard to know how much appetite even presumed allies of renewable energy have for real change. Unless citizens write letters and sign petitions in enough numbers, the biggest oil spill in world history won't change that equation.

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