NASA's satellite data analysis shows that this year's Arctic sea ice minimum extent at 4.64 million square kilometres, is the eighth lowest in the consistent long-term satellite record, which began in 1978.<br/><br/>Arctic sea ice appeared to have reached its yearly lowest extent on September 13, the US space agency said.<br/><br/>Its minimum summertime extent, which typically occurs in September, has been decreasing, overall, at a rapid pace since the late 1970s due to warming temperatures.<br/><br/>The 2017 minimum sea ice extent is 1.58 million square kilometres below the 1981-2010 average minimum extent, NASA said.<br/><br/>The three years with the lowest Arctic ice extents on record – 2012, 2016 and 2007 – experienced strong summer storms that hammered the ice cover and sped up its melt.