Top 10 facts you need to know about the Arctic

1. Six months of perpetual darkness

The North Pole and most of the Arctic has just six months of light each year, starting around April. The remaining six months are continually dark. The coldest recorded temperature in the Arctic is around -68°C (-90°F).

2. Shrinking ice area

Arctic sea ice fluctuates as it melts in the summer months and freezes in the winter. Last September, the area covered by Arctic ice shrunk to just 1.32 million square miles - the lowest on record.

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White area shows ice coverage at its lowest ever level in September 2012. Yellow shows the average ice coverage over the past 30 years. Credit: NASA/Goddard Scientific Visualization Studio

3. Lowest ice measurements within last 10 years

Even when sea ice is at its winter maximum - the 10 lowest measurements since 1979 have occurred in the last 10 years.

4. Ice getting thinner

As well as covering a smaller area, the ice has also been getting thinner. Researchers now believe that Arctic ice lost 36% of its volume between 2003 and 2012 when taking measurements in the Autumn.

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5. Dramatic loud calving

When the edge of a glacier fractures into the sea, it is known as a 'calving' event. These events can be very loud and dramatic, as the film Chasing Ice demonstrated. Recent satellite data shows that a large calving event near the coasts of Canada and Alaska took place in February this year - much earlier than usual.

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6. An ice-free Arctic?

Many experts now believe that the Arctic will now be ice free in the not-too-distant future, although estimates vary. The Met Office has said it does not expect this to happen until after 2030, but many others believe it could happen sooner.

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7. Multi-year ice disappearing

In the past, around three quarters of Arctic sea ice was multi-year ice (thick ice that has built up over many years). Nowadays, it only accounts for 25-30% of the total, while the rest is thinner first year ice that cracks more easily, according to Walt Meier of the NSIDC.

This image shows a comparison of the multi-year sea ice and the first-year sea ice in the last three months of 2012. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

In the image above, the bright white central mass shows the perennial (multi-year) sea ice while the larger light blue area shows single year ice during November, December and January last year.

8. Melting glaciers linked to sea level rises

Melting glaciers are thought to account for around half of the rise in sea levels observed so far. The Greenland Ice Sheet alone makes up about 30% of the total contribution from glaciers to rising seas.

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9. Arctic countries

The Arctic region contains parts of the following countries: Russia, Greenland, Canada, USA, Norway, Iceland, Sweden and Finland. All of these nations, as well as Denmark, jointly administer the area through the Arctic Council.

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10. Danger of melting permafrost

This 23,000-year-old woolly mammoth was found preserved in Siberian permafrost in 1999. Credit: Reuters

As well as the sea ice, scientists are also tracking the melting of the permafront - the frozen layer just below ground surface. When this thaws, it will emit methane, carbon dioxide and other greenhouse gases that will speed up climate change. Scientists think the amount of carbon trapped in permafrost may equal the amount of carbon already in the atmosphere.

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