Since satellite observations began, the extent of sea ice in the arctic has declined dramatically; this year the summer minimum extent was the 3rd-lowest on record. There is also considerable observational evidence that arctic sea ice extent over the last few decades is much lower than it has been for at least a century prior to modern times.
Yet to put such dramatic change in context, one hopes to stretch even further back in time. A team of researchers led by Leonid Polyak of Ohio State University’s Byrd Polar Research Center has culled the available evidence from hundreds of studies of proxy data for sea ice extent. As reported at Science Daily, in a recent paper in Quaternary Science reviews they report their findings: that the present extent of arctic sea ice is at its lowest for at least several thousand years.