Congress and Scientists Disagree About Size of Oil Spill

Are 5,000 or 70,000 barrels of oil leaking each day into the Gulf of Mexico? Scientists and government agencies can't seem to agree.

The National Oceanic and Atmospheric Administration is producing accurate maps of the size of the Deepwater Horizon oil spill -- or at least that's what the federal agency says. It also issues daily forecasts of the future size of the BP (BP) spill and the direction that weather will take it. From the NOAA's standpoint, the size of the spill is just as important as the rate at which oil is leaking. It puts that rate at 5,000 barrels a day.

But questions about the rate of the spill are growing. Representative Edward Markey (D-Mass.) is concerned that the oil well could be leaking more like "70,000 barrels of oil a day, compared with previous estimates of 5,000 barrels," according toBloomberg. Markey says his source is "independent analyses reported in the media," which include comments on National Public Radio. That does not seem like a sound basis on which to make a decision.

Some scientists also say that BP plc (BP) and government estimates are way off the mark. Oceanographer Ian R. MacDonald, an expert in analyzing oil slicks, says his calculations based on satellite imagery suggests the oil leak could "easily be four or five times" larger than the government's estimate, according toThe New York Times. That compares to Markey's estimate of a leak twelve times the government's figure.

The NOAA numbers are "calculated with a protocol known as the Bonn convention that calls for measuring the extent of an oil spill, using its color to judge the thickness of oil atop the water, and then multiplying," the Times reports.

Do the wild swings in estimates matter? Scientists would say "yes" because the amount of oil leaking will eventually determine the extent of the damage to the Gulf shoreline. But the size and impact of the leak is also affected by weather and the success of various efforts to contain, burn, and dissipate the crude. A dispersant called Corexit is being used to dissipate the oil, but dispersants tend to cause oil to drop to the ocean floor, which can cause a whole different set of environmental hazards from those caused by the oil reaching shore.

In a world full of experts, there seems to be very little agreement about the size of the Gulf of Mexico oil spill.