"Especially when you have oil traveling such great distances from the sea floor to the sea surfaces and when you have dispersants and other things that are acting on the oil that might may impact the shape and thickness of the sheen at the sea surface."

Different priorities

BP officials say their priority right now is to stop the leak.

BP spokesman Tom Mueller told the New York Times the company doesn't plan to make any extra efforts to calculate the flow.

"It's not relevant to the response effort," Mueller says, adding that it might even detract from the effort.

Earth scientist Valentine believes the opposite is true: "If we don't know the total amount we are never really going to know where it all went."

In the May 27 edition of the British science journal Nature, Valentine proposes a quick and accurate method for calculating the rate of the spill.

Calculating extent of the spill

He says a more precise estimate of the volume of the spill could be achieved - using existing technology - by measuring methane, the gas which comprises 40 percent of the mass of the leaking petroleum.

Unlike oil which forms globules in water, Valentine says methane dissolves in and moves with the ocean currents as it rises from the ruptured pipe making it easy to measure.

"If we are able to then go in and determine the total amount of methane, right there we have a very large component of the total oil spilled and it's a fairly simple conversion to figure out what the actual amount of spillage was."