My real question is that when looking at the map most of the large deviations are in extreme places. How long do we have temperature records for places like the

My real question is that when looking at the map most of the large deviations are in extreme places. How long do we have temperature records for places like the middle of the ocean near Antarctica? There was a recent article about record breaking temperatures in South America but it turns out the sensors they were monitoring had only been in place from 2008.