Permanent Polar Pack 1946

One of our students was recently looking for maps related to the three Olympic games held in London (1908, 1948, and 2012) to support writing about changes in the city during those times.  As I was scrounging about looking for resources to help I came across an interesting map from 1946 at David Rumsey's marvelous collection of historical cartography made available through the Old Maps Online web portal.

This map was part of the "Ice Atlas of the Northern Hemisphere" - a survey of ice conditions compiled by the U.S. Navy over a number of years.  The maps were based on all sorts of observations.  Maps in the atlas showed monthly averages of ice conditions - the one that caught my eye was the map titled "Ice Chart, Northern Hemisphere, September".  Through this summer reports from the major geoscience agencies in the U.S. have detailed the record melt of Arctic sea ice, as well as the early melt of the Arctic snowcover in spring 2012.

These types of historical documents take on new scientific significance given our current need for data regarding sea-ice and sea temperature change over the past century.