Is a bipolar seesaw consistent with observed Antarctic climate variability and trends?

Abstract

A bipolar seesaw of Arctic and Antarctic temperature anomalies has been reported to be evident in instrumental data on decadal timescales during the last century. This finding hinges upon a global temperature data set that for the area poleward of ∼60°S is derived from only one sub‐Antarctic station prior to the mid‐1940s, and does not include a substantial number of Antarctic stations until the late 1950s. The timeseries of the single‐station record for the early period spliced to the data based on broader coverage for the latter period is an artificial estimate of the Antarctic climate trend and its variability. We estimate the real variability using the original timeseries from the sub‐Antarctic station, a reconstruction of the Southern Annular Mode index, and an ice‐core based reconstruction of Antarctic temperature. None of these Antarctic timeseries are significantly correlated with Arctic or North Atlantic climate records, nor with the index of the Atlantic Multidecadal Oscillation, which was proposed as the driving mechanism of the seesaw. Instead, each of these records is consistently correlated with tropical Pacific sea surface temperatures. However, neither the seesaw nor the tropics alone can fully capture the complexity of Antarctic climate variability and climate change.