Researchers analyzed high-resolution video to determine the volume of the Deepwater Horizon spill. Courtesy U.S. Senate Committee on Environment and Public Works

(The Earth Institute, Columbia University: New York) -- BP's leaking oil well in the Gulf of Mexico was conclusively sealed during the week of Sept. 20, but even now questions remain about the amount of oil that actually came out of it. Initially after the April 20 explosion, officials claimed that the flow could not be measured. Then, as public pressure for information mounted, they looked for ways to measure it and started producing estimates: at first, 1,000 barrels a day, then 5,000, then 12,000 to 19,000, then upward from there.

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