Valentine, who has studied natural methane seeps in the ocean, says scientists can measure the methane in the area around the leak by following the methane plumes.

"The methane that you see is going to be very, very high in concentration compared to anything in the background," he says. "So what we really get is a minimum value. We can say the leakage was at least this much."

Valentine says the U.S. academic research fleet has vessels that can do the job at a cost of a few million dollars or less, but that timing is crucial in reducing the impact of the Gulf oil spill. In his Nature commentary Valentine writes that, "capitalizing on this idea requires immediate action," and he adds "the likely rewards far exceed the costs."