Average monthly Arctic sea ice extent data shows a clear deceasing trend since 1979.
According to the National Snow and Ice Data Center, Arctic sea ice is melting faster than its average over the 1979 t0 2000 period.
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And retreating Arctic sea ice provides even more visible data to support conclusions of warming.
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Credit: National Snow and Ice Data CenterThe graph above shows daily Arctic sea ice extent as of March 22, 2011, along with daily ice extents for 2006, which had the previous lowest maximum extent, and 2007, the year with the lowest minimum extent in September.
According to the US National Snow and Ice Data Center (NSIDC), Arctic sea-ice covered 4.5 million sq km (1.7 million sq miles) at its lowest point on 12 September last year.
Today, the National Snow and Ice Data Center, in conjunction with NASA, announced today that Arctic sea ice has reached a record low since the previous record-breaking low in 2007.
Overall, this will provide Esa with data covering about 2, 000km of sea ice.
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Today, US military weather satellites return daily data on the state of the sea-ice at both poles, but the NSIDC team is keen to retrieve as much information as possible from the early, experimental Nasa Earth-observers.
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Using spacecraft data to make an Arctic-wide assessment of sea ice thickness , a University College London team found the 2008 winter maximum to be about 10% (26cm) below the 2002-2008 average.
The latest data is still being processed but one of the institute's sea ice specialists, Dr Sebastian Gerland, said that though conditions vary year by year a pattern is clear.
One-hundred-and-two holes have been dug so far and 1, 100 measurements have been made of ice thickness, snow density and other features - data deemed vital by scientists evaluating the future of the Arctic sea-ice.
When combined with data on past sea levels, these give an estimate of global temperatures and sea-ice cover for the past three million years.
The National Snow and Ice Data Center reported in early March that 2011 has tied with 2006 for the record low sea-ice coverage in the Arctic Ocean (in the satellite record).
The amount of the Arctic covered by sea ice fell in late August to the lowest point since satellite observations began in 1979, the National Snow and Ice Data Center reported.
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