“Before 1980, before satellite data”
You sure about that?
Yes - we have a daily satellite record of the North Pole ice only since 1980.
South Pole, too, I assume, because polar pictures require a north-south orbit.
It's possible there are ice pictures from earlier satellites with highly eccentric east-west orbits, but no comprehensive daily photographic record of polar ice before 1980.
Satellite temperature data goes back only to about 1975, but coverage of land and sea are different, and coverage of various parts of the atmosphere are different, so there are different data for different satellites launched at different times.