Accelerated warming of the Antarctic interior caused by moist air intrusion from the Weddell Sea

In a new study published in Nature Climate Change, Clem and colleagues reported that the South Pole has experienced a record-high warming of 1.81 ± 1.02°C during the last 30 years, three times larger than the global average. They used observational records to show that the recent warming of the South Pole, which started around 2000 following the downward shift of Interdecadal Pacific Oscillation (IPO), is largely caused by the increased transport of warm and moist air from the Weddell Sea to the Antarctic interior. They further used a series of climate model simulations to suggest that the recent increase in sea surface temperatures in the western tropical Pacific, which is directly linked to the negative phase of IPO, and the associated extra-tropical atmospheric teleconnection produced a strong and persistent cyclonic anomaly over the Weddell Sea, which in turn advected warm and moist air into the Antarctic interior. This study highlights the direct linkage of Antarctic interior to tropical Pacific variability and trend.

Figure 1 from Stammerjohn and Scambos (2020). Changes in Antarctic atmospheric circulation patterns and air temperature: Antarctica as seen from space with illustration of mechanisms discussed by Clem et al. (2020). Stronger westerlies driven by warming, combined with tropical teleconnections from the negative phase of the Interdecadal Pacific Oscillation, produce enhanced cyclonic activity in the Weddell Sea (dark blue arrows). This increases the advection of warm moist air into the high Antarctic interior (red arrows), but shifts wind direction over the Peninsula, slowing the warming there. Bottom, mean annual air temperatures at Faraday/Vernadsky Station and the South Pole (locations shown in top image). Near-record lows (1983, 1987, 1993, 1997 and 1999) and highs (2002, 2005, 2009, 2013 and 2018) are identified in the South Pole series with blue and red squares, respectively.

Clem, K.R., Fogt, R.L., Turner, J. et al. (2020). Record warming at the South Pole during the past three decades. Nat. Clim. Chang. https://doi.org/10.1038/s41558-020-0815-z

Stammerjohn, S.E., Scambos, T.A. (2020). Warming reaches the South Pole. Nat. Clim. Chang. https://doi.org/10.1038/s41558-020-0827-8