Vast, frozen, impenetrable, the Arctic ice-cap has for millennia been one of nature's most formidable natural barriers. Separating continents, climate systems and civilisations, it has remained, pristine and aloof at the top of the world, unscathed by war or human exploitation. Even at the height of the Cold War, when nuclear submarines lurked beneath its ice, the Arctic was accepted by East and West as a demilitarised no man's land, the province of neither communism nor capitalism. Now, suddenly, things are changing. The trickle of melting ice has turned into a political torrent, sweeping away past agreements and limitations and revealing a vast potential source of underwater riches. As a result, an old-fashioned colonial scramble is under way, not for new empires but for oil, minerals and resources.

Rivalry between the five countries bordering the Arctic Ocean - Russia, America, Canada, Norway and Denmark (still the sovereign power in Greenland) - has been growing for a decade, but was dramatically fuelled last year when a Russian mini-submarine planted a titanium flag on the seabed two miles beneath the North Pole. The Russians claimed the feat was intended to reinforce their claim that the Lomonosov Ridge, running north from Siberia, was an extension of the Siberian continental shelf. This, they argued, provided the geological evidence required by the 1994 Convention on the Law of the Sea to award sovereign seabed exploration rights.

Russia's Arctic neighbours saw the exploit as a blatant land grab, an attempt to pre-empt any new agreement on sharing the undersea resources among the littoral powers. They have already begun moves to stake their claims: Norway and Denmark are carrying out surveys and the US is organising an expedition ostensibly “in search of hydrothermal vents and new biological life” but probably with more commercial interests in mind. The Russian move prompted Denmark to call a high-level conference, which opened in Greenland yesterday, of the five Arctic powers.

All are committed to the preservation of polar peace and stability. But all know how much is at stake. Unlike the colder and far larger Antarctic continent, there is no international treaty governing the Arctic nor any prohibition on exploitation, military activity and human settlement. It is estimated that perhaps a quarter of the world's oil and gas reserves could lie under the ocean, with other scarce minerals worth billions of pounds. At a time of sharply rising commodity prices, there is a strong temptation for all five nations to cut a deal among themselves and start drilling.

There is a long way to go, however, before either the technology or political framework is in place. Despite the shrinking ice-cap, it will be decades before it is possible to pump oil outside the established 200 nautical miles. And the accelerating melting has already so alarmed environmentalists that there is strong pressure to establish an international regime in the Arctic that would certainly come into conflict with national claims. At present, there is no way of enforcing global rights in the area. The Greenland conference must therefore focus on the immediate - new navigation routes, maritime security and oil spills - as well as the long-term reconciliation of interests. An ugly fight for resources at the top of the world would simply start a new cold war.