1972 was a VERY cold year. It's a shame that NASA doesn't have observations back to the beginning of the 20th century. We know from terrestrial observations t

1972 was a VERY cold year. It's a shame that NASA doesn't have observations back to the beginning of the 20th century. We know from terrestrial observations that arctic ice cycled down (below where it is now) in the early 20th century, and then ramped up and peaked sometime around the beginning of this video. It was cycling down again until about 10 years ago and has been relatively stable since then.