Amount of Leaking Oil May Still Exceed Federal Estimates, Scientists Say

BY Lea Winerman  May 28, 2010 at 6:45 PM EST

The amount of oil that has been leaking into the Gulf of Mexico for more than a month may be significantly higher than the preliminary estimate released Thursday by a federal panel, some scientists on the panel told the PBS NewsHour Friday.

On Thursday, U.S. Geological Survey director Marcia McNutt announced that the Flow Rate Technical Group — a panel of scientists from government and academia — had determined that the overall best initial estimate for the rate of flow from the leak was between 12,000 and 19,000 barrels of oil per day.

But at least two experts on the panel say that those numbers actually represent what they consider the lower boundary range of the possible amount of oil.

The 12,000-to-19,000-barrel estimate was based on individual estimates from three different methods: one that used satellite images to study the amount of oil on the surface of the water, one that analyzed video of the underwater oil “plume,” and one that analyzed the amount of oil collected by the Riser Insertion Tube Tool (RITT) that BP installed last week to capture some of the escaping oil.

But it was impossible for members of the team that analyzed the oil plume video to estimate the upper boundary of the oil spilled, according to the Ira Leifer, a researcher at the Marine Science Institute at the University of California, Santa Barbara, and Steven Wereley, a researcher at Purdue University.

Wereley and Leifer were both members of that team, and Leifer participated in the satellite image analysis as well. Both researchers say that the seven minutes of video that BP provided to the plume team was not sufficient to estimate the upper boundary of the amount of oil — only to give a lower-end estimate.

“What everyone on the panel agreed was that due to the low-quality data BP provided to us, it would be irresponsible and unscientific to estimate an upper bound to the emission,” said Leifer. “So what we presented in the [plume team] report is a range of expert opinions on what the lower bound is.”

Wereley said he was surprised to see the estimate of 12,000 to 19,000 barrels and was “disappointed” with the way that the press release was phrased.

“I was really confused when I read the press release yesterday,” he said. “I had to read it several times.”

An official from Department of the Interior agreed that the plume analysis did not set an upper limit on the amount of oil spilled, but said that the estimate of 12,000 to 19,000 barrels per day was based on the area of overlap between the three different methods of estimating the flow.

But Leifer said that he thought combining the analyses this way was comparing apples to oranges.

Meanwhile, all of the panel members emphasized that the results presented Thursday are preliminary.

“As the FRTG collects more data and improves their scientific modeling in the coming days and weeks ahead, they will continue to refine and update their range of oil flow estimate rates,” the Department of the Interior said in a press release Thursday.

And Wereley said that BP had provided more video as of Thursday, which the panel will begin to analyze soon in an attempt to define an upper limit for the spill.

Updated 8:55 a.m., Saturday, May 29

Interior Department spokeswoman Julie Rodriguez said in a written statement:

The FRTG was assembled on the principle that, given the complexity of estimating a flow rate at 5000 feet below the surface of the water, many different scientists and approaches should be brought together to try to find best estimates at this point in time. As Dr. McNutt made clear yesterday, there are and will continue to be, differing estimates and conclusions within the group. Differences among the estimates of each team within the group, and of individual scientists within the FRTG represent a healthy and important part of the process that will continue to help us get closer to more and more accurate estimates.