The Arctic is an ocean surrounded by land, unlike the Antarctic at the other end of the world, which is a continent surrounded by water.

Its vast territory of 21 million square kilometres (7.7 million square miles) stretches from the North Pole to the Arctic Circle.

Bordered by North America, Asia and Europe, it spans eight countries or territories: Russia's northernmost coast, Finland, Sweden, Norway and Iceland, Greenland, Canada and the US state of Alaska.

The Arctic Ocean connects to the south with the Atlantic and to the west with the Pacific via various straits.

Polar nights

Its extreme climate means living conditions can be very tough.

With temperatures sometimes falling below minus 50 degrees Celsius (minus 58 degrees Fahrenheit) and with a very low level of light for much of the year -- including "polar nights" in which nighttime lasts more than 24 hours -- its only vegetation is the tundra, a vast, treeless area of low swampy plains.

At the height of winter, ice forms to cover 14 million square kilometres of ocean. In summer, it melts to less than five million square kilometres -- or even four million, with the annual melt being accelerated by global warming.

Voters stand in line to cast their ballots for the parliament election at a polling station in Greenland's capital Nuuk, on April 6, 2021. The autonomous Danish territory of Greenland votes Tuesday in legislative elections, after a campaign focused on a disputed mining project, as the Arctic island confronts first-hand the effects of global warming.

Voters stand in line to cast their ballots for the parliament election at a polling station in Greenland's capital Nuuk, on April 6, 2021. The autonomous Danish territory of Greenland votes Tuesday in legislative elections, after a campaign focused on a disputed mining project, as the Arctic island confronts first-hand the effects of global warming. (AFP)

Four million inhabitants

Some four million people live in the Arctic region, including around 500,000 people from dozens of distinct indigenous cultures such as the Inuit, the Aleut, the Sami and Yakut.

Many depend on the ocean and its wildlife for food and income.

An Arctic Council was set up in 1996 to discuss issues such as the environment and economic and social development, and foreign ministers of the member states meet every two years.

Ecosystem threatened

The Arctic, which is home to some 21,000 known animal and plant species, is one of the last vast regions of the world to remain in a wild state.

But the development of human activities including fishing, transport, tourism and drilling has threatened its fragile ecosystem.

Since the 1990s, climate change driven has pushed up temperatures in the Arctic twice as fast as the world average.

In 2019, the region saw its second hottest year since 1900 and the second smallest ice floe ever registered.

The ice shrank even more in 2020.

Global warming, which reduces the part of the Arctic Ocean that is permanently covered by ice, puts at risk species such as polar bears, bowhead whales, seals and sea birds.

While the melting of the Arctic ice pack in the ocean has no impact on sea levels, the melting of the huge Greenland ice sheet is a cause for concern. Were it to completely disappear it would lead to a seven-metre (2.1 feet) rise in sea levels.

Other alarming phenomena include the emergence of major forest fires in remote areas and the melting of the permafrost, which houses large quantities of methane, a greenhouse gas much more powerful than CO2.

In this handout photo taken from a footage released by Russian Defense Ministry Press Service on March 26, 2021, A Russian nuclear submarine breaks through the Arctic ice during military drills at an unspecified location.

In this handout photo taken from a footage released by Russian Defense Ministry Press Service on March 26, 2021, A Russian nuclear submarine breaks through the Arctic ice during military drills at an unspecified location. (AP)

Undiscovered resources

The Arctic is estimated to hold around 13 percent of the world's undiscovered oil and 30 percent of its natural gas reserves.

The melting of the Arctic ice cover has made the region more accessible to shipping as well as oil and gas extraction, making it increasingly coveted by neighbouring and distant countries, including China.

Russia has made the development of the region's natural resources a priority, while Norway estimates that the Barents Sea holds more than 60 percent of the country's untapped oil reserves, although drilling there has so far been disappointing.

Former US president Donald Trump approved oil and gas exploration in the US's biggest wildlife reserve in Alaska in August, but his successor Joe Biden has since blocked those efforts.

Greenland is also attracting interest from mining companies, although the new local government has vowed to stop a controversial uranium and rare earth mineral mine project.

Danish Foreign Minister Jeppe Kofod (second right), Greenland's Minister of Foreign Affairs Pele Broberg (left) and Jenis av Rana (second left), Minister of Foreign Affairs of the Faroe Islands, stand alongside U.S. Secretary of State Antony Blinken prior to meetings at the Danish Ministry of Foreign Affairs, Eigtveds Pakhus, in Copenhagen, Denmark, on May 17, 2021.

Danish Foreign Minister Jeppe Kofod (second right), Greenland's Minister of Foreign Affairs Pele Broberg (left) and Jenis av Rana (second left), Minister of Foreign Affairs of the Faroe Islands, stand alongside U.S. Secretary of State Antony Blinken prior to meetings at the Danish Ministry of Foreign Affairs, Eigtveds Pakhus, in Copenhagen, Denmark, on May 17, 2021. (Reuters)

Territorial disputes

Alongside interest in resources there has been an escalation of territorial claims in recent years with Moscow, Washington, Ottawa, Oslo and Copenhagen all weighing in with demands to extend their portion of the continental shelf.

The US is still gathering data to potentially make a claim, even though it has not ratified the UN Convention on the Law of the Sea.

Strategic shipping route