More than a quarter of a million satellite images taken by NASA's Nimbus weather satellites, the first of which was launched in 1964, have been digitized and analyzed by scientists at the National Snow and Ice Data Center.
The generally accepted satellite record of world ice begins in 1979, but this new data extends the record back to 1964. The 1960s was a colder decade globally than any time since, so it is no surprise that Arctic and Antarctic sea ice was generally more extensive then.
But the data do reveal a few surprises; large holes in the Arctic ice which seem to defy explanation during the very cold 1960s. The data has also revealed more variability in Antarctic ice during the 1960s, including what would now be considered a record low areal coverage in 1966.
It is possible that weaker atmospheric circulation around Antarctica compared to recent years allowed for greater inter-annual variability.
