Global warming and its effect on the Arctic seems to be regarded as recent phenomena but sixty years ago scientists were already concerned about reports of loss of ice cover in the Arctic Ocean and a reduction in ice thickness.
Although there weren’t too many satellites available in 1916 to give a decent coverage of ice conditions, there were a few ships around. Here are the monthly charts for the summers of 1916 and 2016; make what you will of them.
Charts for 1916 are from here: http://brunnur.vedur.is/pub/trausti/
The charts there are in the zip-files at the bottom of the page in either jpg or pdf.
Charts for 2016 are from: http://www.iup.uni-bremen.de:8084/amsr2/