(CNN) -- One of the planet's most fragile and pristine ecosystems sits atop a bounty of untapped fossil fuels.

Melting polar ice is making the Arctic more accessible to shipping and other industry.

The U.S. Geological Survey estimates that 90 billion barrels of oil, 44 billion barrels of natural gas liquids and 1,670 trillion cubic feet of natural gas are recoverable in the frozen region north of the Arctic Circle.

And the fight over who owns those resources may turn out to be the most important territorial dispute of this century. Russia, Canada, the United States, Denmark, Norway, Sweden, Iceland and Finland all have a stake in the Arctic's icy real estate.

But both the exploration, and the likely drilling at the top of the Earth, have scientists deeply concerned. One reason: Global warming has hit the Arctic's plant and animal life ferociously. The stresses and possible pollution caused by drilling only increase the risks.

"The ecosystem that is there has been protected by thousands of years of ice. Even if there was no territorial dispute, the ice is going away," said oceanographer David Carlson, director of the International Polar Year's Program Office.

The International Polar Year (http://www.ipy.org/) is a global scientific study focused on the Arctic and the Antarctic from March 2007 to March 2009.

Arctic sea ice is usually 1 to 3 meters, or as much as 9 feet, thick. It grows during autumn and winter and shrinks in spring and summer. Scientists have monitored sea ice conditions for 50 years.

The disappearance of the ice in the past decade is astounding, climate scientists say.

"We've been seeing a retreat year after year," said Marika Holland, an oceanographer with the National Center for Atmospheric Research in Boulder, Colorado. "The sea ice loss we observed in the summer of 2007 was shocking."

Soon there may be no sea ice anywhere in the Arctic during some months of the year.

Although environmentalists are concerned by this melting trend, shipping and energy companies are salivating at the prospect of smaller ice caps, which makes Arctic drilling and commerce easier. Cargo ships may be able to travel from Asia to North America more cheaply and efficiently, for example.

Have you been to the Arctic Circle? Share travel photos and tell us what you thought

Diplomats, politicians and oil company executives are feuding over who owns what under the ice. But the real power players might be the geologists who evaluate undersea land formations.

Unlike Antarctica, which has a treaty that prohibits territorial claims, there is no agreement for the vast expanse of the Arctic. So questions about drilling rights and shipping lanes, let alone who bears responsibility for environmental damage, are somewhat murky.

According to the United Nations Convention on the Law of the Sea, countries are entitled to exclusive economic zones up to 200 miles from their shores. Some countries with a stake in the Arctic's riches are trying to extend that zone, some in more brazen ways than others.

In a showy technological display August 2, 2007, a Russian submarine planted an underwater flag 14,000 feet (4,200 meters) below the North Pole.

Russian scientists are keen on proving that the seabed below the North Pole is part of the Eurasian continental shelf, an area called the Lomonosov Ridge.

If that's the case, the region would be under Russian control. Moscow argued before a United Nations commission in 2001 that the ridge is an extension of its continental territory. But the U.N. asked for more evidence.

Meanwhile, dueling geologists elsewhere are looking for land formations with a different provenance. Danish scientists are trying to prove that the Lomonosov Ridge is connected to Greenland, and Canadian scientists are looking for links between the ridge and Ellesmere Island, a Canadian territory.

Some territorial questions are not in dispute, however.

"Most of the estimated undiscovered resources are in areas with agreed-upon territorial boundaries," said Don Gautier, research geologist at the USGS.

"Exceptions are the East Barents Basins, where Russia and Norway are involved in bilateral discussions of the offshore boundary. Another exception is the Alaska./Canada boundary offshore, which is also subject to bilateral discussions between U.S. and Canada," he said.

The United States has unrestricted access to Arctic resources in northern Alaska. But the Bush administration's sale of oil drilling rights in prime polar bear habitat has upset environmentalists, who fear drilling's impact on the threatened species. iReport.com: See photos of a pipeline in Alaska

Security expert John Pike, director of GlobalSecurity.org, thinks power in the Arctic may lie with whoever has the best physical access to this forbidding region.

"The Russians have got a half-dozen icebreakers. Americans have a pair of icebreakers, but they are old and worn out," Pike said.

And of course, much of countries' access to the Arctic will come down to money.

"Building a ship to operate in a foot of ice is no big deal. Building an icebreaker that can get through 2 yards of ice, now you're talking serious icebreaking. The Russians can get through 2 yards of ice without breaking a sweat," Pike said.

Ultimately, questions about what is drilled for in the Arctic, and by whom, will depend on the global economy. Recovering oil from a forbidding frozen wilderness makes sense when it's selling for $150 a barrel, but not so when it is at $40 a barrel.

CNN's Brandon Griggs contributed to this report.

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