The climate swing the researchers discussed, known as the Atlantic Multidecadal Oscillation (AMO), shows up as a cycle of warmer, then colder-than-normal sea-surface temperatures. The cycle repeats itself once every 40 to 80 years or so, with cooler or warmer temperatures lasting for periods of 20 to 40 years or more. Since the mid-1990s, the AMO has been in a warm phase.

If the results hold up to additional scrutiny, they would suggest that the initial trigger for the rapid warm-up of the Antarctic Peninsula and a key driver behind its intensification to date is natural variability, in addition to any influence from global warming.