are now able to drain several oil fields from one platform. And new horizontal drilling techniques allow more oil to be extracted from a single well.

Major infrastructure – such as roads, jet landing strips, repair shops, homes and industrial complexes – is, of course, still necessary and could disturb wildlife that is accustomed to pristine land, said Charles Clusen, director of National Parks and Alaska Projects for the Natural Resources Defense Council.

Similar concerns about wildlife arose before construction of the Alaskan Pipeline, built in the 1970s.

"But there hasn't really been any effect on the wildlife; they congregate near the pipeline and it doesn't seem to bother them," said UT's Eric Potter.

However, any development of the Arctic National Wildlife Refuge (ANWR) for drilling, as President Bush has long advocated for, could have a greater impact. Polar bears, caribou and other animals trek across this unique area to give birth, said Clusen. Birth is the most vulnerable time in a species’ life cycle and disrupting it will lead to diminished populations, he explained.

The true overall environmental impact of oil drilling is hard to gauge, due to the paucity of baseline studies, said Jeff Short, a supervisory researcher for the U.S. National Oceanic and Atmospheric Administration (NOAA).

In the wild, most animals quickly flush PAH, a toxin associated with oil wells, from their bodies — which is why PAH rarely concentrates in the food web and is of minimal risk to humans. The animal’s justifiably panicked immune response to PAH can cause cancer — especially if the animal is exposed continually by, say, living near an oil platform, explained Short.

As for human populations, many coastal communities depend on tourism and fishing — both of which may be affected by off-shore drilling by increased development, pollution and disruption of marine life habitats. Among traditional communities in the ANWR, some oppose drilling while others have cautiously welcomed it — within limits — for the improved access to jobs and amenities it could bring.

Even a perfectly functioning oil well is a cause of concern due to "produced water," explained Short.

Produced water — which rises with oil and contains environmental toxins such as polycyclic aromatic hydrocarbons (PAH) — is usually tossed overboard. At high concentrations, the contaminants are lethal to marine life. At lower concentrations, according to lab experiments, they can cause birth defects, impaired growth and skewed sex ratios.

Prices at the pump

Estimates for the output of oil drilling sites can only accurately be given in very large ranges, Potter explained. For example, the Energy Information Administration predicts ANWR could produce between 1.9 and 4.3 billion barrels of oil, and that might not do much for our pocketbooks. In 2007, the United States consumed 7.5 billion barrels, according to the U.S. Energy Information Administration (EIA).

In the best-case scenarios, said Clusen, "we're talking lowering the price of gas by three cents, 20 years from now."

The American Petroleum Institute is more optimistic. "When we went into Prudhoe Bay [in northern Alaska], we expected nine billion barrels, and we have already pumped 15," Radford said. And the White House estimates that lifting the drilling bans would produce an extra 18 billion barrels from various locations.

But the federal EIA sees no short-term value in additional drilling, a process that takes years for awarding contracts and obtaining permits.

"Access to the Pacific, Atlantic, and eastern Gulf regions would not have a significant impact on domestic crude oil and natural gas production or prices before 2030," the EIA states on its web site. "Leasing would begin no sooner than 2012, and production would not be expected to start before 2017."

Potter and others note that drilling that began 30 years ago, such as in Prudhoe Bay, Alaska, are helping meet today's demands.