With gas prices skyrocketing and President Bush and other politicians calling to lift a ban against offshore drilling, a polarized debate has again flared up over the true risks and rewards of this approach to oil prospecting.

"There are extremes on both sides," said Judy Penniman of the American Petroleum Institute.

A federal ban was initiated by Congress in 1981 to protect sites off California and Massachusetts and has been repeatedly expanded since then. President George H.W. Bush put his own ban in place, by executive order, in 1991, and Bill Clinton extended it to 2012. Together, the rules now thwart drilling in Alaska's oil-rich Arctic National Wildlife Refuge and elsewhere.

Scientists and politicians disagree on how much effect any new drilling might have on prices at the pump. Further, they argue about potential impacts on the ecosystem.

Impact on marine life

Concerns over new drilling amount to more than just a worry about spills.

To find potential oil reserves, researchers send seismic waves into the ground. The waves bounce back to reveal the buried topography and can hint at a possible reserve. But seismic noise disorientates whales and leads to mass beachings, said Richard Charter, a government relations consultant for the Defenders of Wildlife Action Fund.

Laboratory experiments attempting to pin down the impact of seismic waves on wildlife often must rely on caged animals, which raises questions about whether the animals would have fled and avoided ear damage if they could have, note Robert McCauley and colleagues in The Journal of the Acoustical Society of America.

However, Andy Radford, a policy advisor at the American Petroleum Institute, isn’t worried. "[We] make sure there are no whales in the area when we are doing our seismic search," Radford said.

Several weeks ago, ExxonMobil suspended exploration near Madagascar because more than 100 whales had beached themselves.

Ultimately, the seismic tests only help geologists make educated guesses. "You never know until you drill," said Eric Potter, associate director of the Bureau of Economic Geology at the University of Texas at Austin. The usual outcome is failure, Potter said, sending wildcatters back to the seismic drawing board.