Record low for Arctic sea ice extent

29 08 2012

This week the National Snow and Ice Data Centre (NSIDC) announced that Arctic sea ice extent has reached a new record low since satellite data records began in 1979.

According to the NSIDC, observations show there were 4.1 million square kilometres (1.58 million square miles) of sea ice on 26 August.

Arctic sea ice extent  The black line shows the 1979 to 2000 median extent.  Credit: National Snow and Ice Data Center

This is 70,000 square kilometres (27,000 square miles) less than the previous record low set on 18 September 2007.

The previous record was the sea ice minimum for the year – which normally occurs at the end of summer before cooler temperatures sea ice start to form.

The July 2012 ice extent was the second lowest observed during the satellite era, following the record low observed in 2011. The synoptic conditions during the month were variable, and much of the Arctic was relatively warm with temperatures 1-3 degrees Celsius above the 1981 to 2010 average over the Beaufort Sea and regions to the north. 

By 1st August the daily extent was lower than the previous record low for the time of year recorded in 2007, and has since remained at a record low value. Between 4th and 9th August there was an extremely rapid loss of ice cover in the East Siberian Sea, coinciding with a severe storm over the Central Arctic. This rapid loss of ice cover may have been caused by ice breaking up and melting due to the strong winds generated by the storm, although it is also possible that the melt would have occurred anyway at this time as the ice concentration in this region was already low.   

With this previous record already broken in August, it’s likely this year’s sea ice extent will continue to decline into September. The NSIDC will announce when the Arctic sea ice extent has hit a minimum for this year when this occurs, most likely toward the middle of next month.

Declining trend in sea-ice

Satellite records began in 1979 and have shown a long-term decline in sea ice extent. However, the rate of decline has accelerated in the past 15 years and the last five years make up the lowest five extents in the 32-year record.

Climate models which simulate future Arctic sea ice extent show wide variations, but Met Office results suggest the area could be nearly ice-free in summer as early as 2030.

However, models do not suggest the current accelerated rate of decline would continue or that there was any ‘tipping point’ from which ice extent could not recover.

What are the impacts for the UK?

Long-term changes in Arctic sea ice are likely to have impacts locally in the Arctic as well as driving changes in European and global climate.

As the sea ice decreases, the immediate impact is for a the lower atmosphere in the Arctic to be warmed by the Arctic Ocean – which is relatively warm compared to the ice cover.

However, there is also evidence that depleted sea ice alters atmospheric circulation patterns outside the Arctic throughout the following months and into winter.

This appears to result in high pressure over the Arctic and low pressure further to the south over the mid-latitudes – which in turn tends to drive more easterly winds across Europe, particularly in winter.

While other factors are also involved in determining winter climate, this raises the risk of cold winter conditions over northern Europe.

However, the relative importance of sea ice conditions and other factors in producing cold winters is being investigated by Met Office scientists and others.

You can read more about Arctic sea ice in our research news pages.


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