A History of Incorrect Oil-Spill Estimates

An aerial view of the BP oil spill as it spreads, on June 13, 2010. Spencer Platt/Getty Images

Over the course of the last two months, the estimate for the amount of oil billowing from the BP spill in the Gulf of Mexico has gone from 1,000 barrels per day to 60,000 barrels. Here's a brief history of who was wrong, and when.

Just after the Deepwater Horizon rig exploded and sank, on April 20, BP claimed that a mere 1,000 barrels of oil, or 42,000 gallons, was leaking into the ocean.

On May 14 the government, over protests from BP, announced that 5,000 barrels of oil per day were leaking into the ocean. They were immediately criticized by experts, reported The New York Times, for making a hasty guess using "a method that is specifically not recommended for major oil spills."

At about this time BP claimed that there was no reliable way to measure the spill. Those pesky experts then pointed out that there was a method, called "particle-image velocimetry," that would work.

On May 27 three teams using three different methods announced that they estimated the leak was, in fact, more likely to be between 12,000 and 19,000 barrels per day. Many experts revealed that they had thought that all along.

On June 10 that estimate was doubled to somewhere between 25,000 and 30,000 barrels a day by the same teams.

Yesterday, on June 16, the team—this time bolstered by the personal involvement of Nobel Prize–winning Energy Secretary Steven Chu—used pressure readings and high-resolution video to make a new estimate: 60,000 barrels a day. In a statement Chu said that "… it is important to realize that the numbers can change."

We will update this story next time the estimate, inevitably, creeps upward.