Scientists are squabbling with the government about what happened to the estimated 4.9 million barrels of oil that spewed into the Gulf of Mexico from the BP well before the well was capped.
The dispute started a couple of weeks ago, when the federal government released a report that left the impression that most of the oil was no longer a problem. In releasing what it called its oil budget, the government said the vast majority of oil had evaporated or been captured, vacuumed up, burned or dispersed. And much of what was left in the Gulf was degrading quickly.
Some scientists couldn't believe what they were reading.
"We saw some press reports that 75 percent of the oil was gone, and we were alarmed at hearing that number," says Chuck Hopkinson, a marine science professor at the University of Georgia and director of the Georgia Sea Grant. Hopkinson says he believes those reports gave the public an "absolutely incorrect" impression, which the government failed to contradict. He gathered a group of scientists who came up with an assessment that 70 percent to 79 percent of the oil remains in the Gulf.
Government Sticks By Estimates
But the government is sticking by its study and takes issue with the competing report.
"I have great respect for the Georgia scientists, but I think the report that they issued is actually puzzling and confusing," says Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration.
Lubchenco says part of the confusion comes from the fact that the Georgia scientists didn't include in their calculations oil from the well that was captured before it got into the Gulf. The government says BP collected or burned 17 percent of the oil above the water surface.
"It's hard to compare one to the other when you have different starting numbers," Lubchenco says. "It's comparing apples to oranges, and it skews the numbers upward."
How Much Oil Evaporated?
But that's not the only major difference between the reports. The government estimates that a quarter of the BP oil evaporated. The Georgia scientists argue that much less did, somewhere between 7 percent and 12 percent.
Lubchenco stands by her estimate. She says it comes from experts inside and outside the government who understand the particular chemistry of the light petroleum that spewed from the well.
But Hopkinson from Georgia Sea Grant -- a NOAA-funded program -- says his team believes much of the oil is trapped in plumes deep underwater so it couldn't evaporate.
"To evaporate, it has to rise to the surface and have contact with the atmosphere," he says. "Because so much of the oil is at deeper depths, we didn't think it was realistic to assume that the entire volume evaporated."
Some scientists worry that a misperception that most of the oil is gone could undercut the massive research effort still needed to track down the facts.
"There's oil in the water. There's oil on the seafloor. There are going to be impacts to the system," says Samantha Joye, another University of Georgia marine science professor. "If we assume that there is no longer a problem and we stop making measurements, then there are going to be a lot of unknowns."
Edward Overton, an environmental scientist at Louisiana State University, says the government and the Georgia scientists are basing their reports on educated guesses.
"All of these are based on very little actual data," Overton says. "The bottom line is that we really don't know how much oil is left out there."
Overton is making his own educated guesses and says both the government and the Georgia scientists are underestimating how much oil has evaporated. But he thinks there's a lot of room for knowledgeable scientists to disagree.
"We won't know who is right for some time yet because we've got to go out and do the analysis down in the deep oceans and try to find the oil, see if it's there, see how quickly it's degrading, and all of that takes time," he says.
In fact, Overton says, we may never know, because much of the data may be impossible to recover. Still, all the scientists agree that the tremendous amount of oil that spewed into the Gulf has done and will do serious harm to marine life.