One hundred sixty countries have acceded to the pact and the Obama administration is making a new push for Senate approval. Refusing to sign on means the U.S. could be frozen out of its share of the spoils.Arguing for its ratification at a Senate hearing last week, Clinton said the treaty would offer the U.S. oil and gas rights some 600 miles into the Arctic. "American companies are equipped and ready to engage in deep seabed mining," she said. "But the United States can only take advantage of the ... mine sites in areas beyond national jurisdiction as a party to this treaty." The Arctic's warming is occurring at least twice as fast as anywhere else on earth, threatening to raise sea levels by up to 5 feet this century and possibly causing a 25 percent jump in mercury emissions over the next decade. The changes could threaten polar bears, whales, seals and indigenous communities hunting those animals for food, not to mention islands and low-lying areas much farther afield, from Florida to Bangladesh. But the rapidly changing climate is also changing the realm of what is possible from transportation to tourism, with the summer ice melting away by more than 17,000 square miles each year. During the most temperate days last year, only a fifth of the Arctic Circle was ice-covered. Little of the ice has been frozen longer than two years, which is harder for icebreakers to cut through. Europeans see new shipping routes to China that, at least in the warmth and sunlight of summer, are 40 percent faster than traveling through the Indian Ocean, the Suez Canal and the Mediterranean Sea. A northwest passage between Greenland and Canada could significantly speed cargo traveling between the Dutch shipping hub of Rotterdam and ports in California. And the eight-nation Arctic Council, which is being established in Tromso, is hoping to manage the new opportunities in a responsible way. Talking to reporters Friday, Clinton urged the governments to "begin working together to make plans for what will most certainly become greater ocean travel, greater exploration, therefore greater pollution, greater impact of human beings."