Increase of the Antarctic Sea Ice Extent is highly significant only in the Ross Sea

Abstract

In the context of global warming, the question of why Antarctic sea ice extent (SIE) has increased is one of the most fundamental unsolved mysteries. Although many mechanisms have been proposed, it is still unclear whether the increasing trend is anthropogenically originated or only caused by internal natural variability. In this study, we employ a new method where the underlying natural persistence in the Antarctic SIE can be correctly accounted for. We find that the Antarctic SIE is not simply short-term persistent as assumed in the standard significance analysis, but actually characterized by a combination of both short- and long-term persistence. By generating surrogate data with the same persistence properties, the SIE trends over Antarctica (as well as five sub-regions) are evaluated using Monte-Carlo simulations. It is found that the SIE trends over most sub-regions of Antarctica are not statistically significant. Only the SIE over Ross Sea has experienced a highly significant increasing trend (p = 0.008) which cannot be explained by natural variability. Influenced by the positive SIE trend over Ross Sea, the SIE over the entire Antarctica also increased over the past decades, but the trend is only at the edge of being significant (p = 0.034).

Arctic and Antarctic Sea Ice Change: Contrasts, Commonalities, and Causes

“…This recent variability is further discussed in Section 6. These findings agree with the results of Yuan et al (2017), who, using a more sophisticated trend analysis accounting for persistence, suggested that significant positive trends are present only in the Ross Sea. Overall, Arctic change dwarfs Antarctic change, so that the global sea ice cover is strongly decreasing.…”

Effects of an Explosive Polar Cyclone Crossing the Antarctic Marginal Ice Zone

“…Climate models struggle to capture this regional and temporal variability (Hobbs et al, 2014;Lecomte et al, 2016;Zunz et al, 2013), as well as the timing of the winter expansion and summer retreat (Hobbs et al, 2014). Different regions have shown a combination of positive and negative trends, whose significance is linked to the choice of statistical analyses (Yuan et al, 2017). Part of the dilemma on what is driving changes in Antarctic sea ice has been attributed to these opposing trends, thus reducing the consensus on a large-scale mechanism (Hobbs et al, 2016;Matear et al, 2015).…”

Moisture transport and Antarctic sea ice: Austral spring 2016 event

“…Even though the trend itself is modest (Yuan et al, 2017), it is somewhat problematic in the context of the overall global warming signal. When looking at the SIE anomalies over the last 38 years, the first 8 months of 2016 are not particularly anomalous (not shown).…”