From the very beginning of the BP oil spill—when reporters were told that there probably was no oil spill at all—the people in charge have consistently underestimated the size of the spill. After that initial mistake, BP told us that oil was flowing at about 1,000 barrels a day from the blown well. (Each barrel contains about 42 gallons of oil.) Then—partially under pressure from the government—that figure was raised to 5,000 barrels a day. That estimate came under attack from scientists and environmentalists who saw the surface spill as far larger—and when BP, again under pressure, released underwater video of the blown well, it was revised upwards once more to between 12,000 and 19,000 barrels a day. By June the estimate was raised again to between 20,000 and 40,000 barrels a day, and in the middle of the month came a new range: 35,000 to 60,000 barrels a day.
That range was held up as the best the team of government and academic scientists assigned to the problem could do—until today. Using new data from pressure readings of the capped well and models of the Macondo oil reservoir, the team has come up with what is likely to be the final estimate: 4.9 million barrels in total, or about 206 million gallons of oil. In the days immediately before the well was capped on July 15, 53,000 barrels of oil were flowing—on the high end of the previous estimate. And interestingly, the scientists believe that in the early days of the spill even more oil was flowing—approximately 62,000 barrels a day. (They think the flow rate declined over time as the reservoir depleted, reducing the pressure pushing oil out of the blown well.) You can read the full government press release here.
The new numbers confirm what most of us had already believed—that the BP oil spill is the biggest accidental spill in history, much bigger than the Ixtoc I well blowout off the coast of Mexico in 1979, which released around 3.3 million barrels of oil into the southern Gulf. The Exxon Valdez spill in 1989 was a comparatively tiny 750,000 barrels. (All of these incidents are likely smaller the Gulf War spill in 1991, when Saddam Hussein’s retreating troops sabotaged Kuwaiti oil terminals and platforms, resulting in 4 to 6 million barrels of crude slipping into the Persian Gulf—but as an act of war, that’s generally categorized separately from industrial accidents.)
The new figures also show—again—that this spill consistently surpassed the worst-case estimates of BP and the government. The estimate may also help the government assign penalties to BP—under the Oil Pollution Act, companies can be fined $1,100 to $4,400 per barrel spilled, depending on the degree of negligence. That adds up to between $5.39 billion and $21.56 billion in fines, although it wouldn’t be surprising to see the government seek a negotiated settlement.
The well remains capped—though the planned static kill has been put off a day—and all that oil seems to be vanishing from the surface of the Gulf, even if much of it remains unaccounted for. Nature is resilient—it could be, as writers like TIME’s own Michael Grunwald have suggested—that the ultimate damage from the spill may not be that bad. But after this newest round of data, no one can argue that the BP spill isn’t record-breaking.
And the really sad thing? Large as the spill is, the total amount of oil that flowed into the Gulf over nearly 100 days is about 4 times less than what the U.S. uses on a daily basis, as this chart from the Atlantic‘s Alexis Madrigal shows:
The true environmental catastrophe isn’t the BP spill, bad as it is. It’s our unbreakable addiction to oil.