Air Temperature Trends and Extreme Warming Events Across Regions of Antarctica for the Period 2003–2021

We have characterized the magnitude and spatial extent of observed regional and inter-regional air temperature trends and warming extremes across Antarctica. Prior studies have used localized observational records to analyze air temperature trends across distinct geographical regions, leaving local and inter-regional variations to be undetected. Using the high-resolution temperature product AntAir ICE, air temperature trends and extreme warming events were identified across Antarctica for the period 2003–2021. Unsupervised clustering was applied to austral summer and annual mean air temperature trends to divide Antarctica into 12 regions exhibiting similarity in temperature trends. Our results show a significant annual mean cooling trend of ‒$0.12\frac{°C}{\text{Yr}}$ for the terrestrial Antarctic Peninsula, and an austral summer (annual) warming trend of +$0.08\frac{°C}{\text{Yr}}$ (+$0.07\frac{°C}{\text{Yr}}$) in the Ross Sea region's Victoria Land and Transantarctic Mountains. The spatial extent of each of the 12 clusters' extreme air temperature events was mapped in austral summer revealing that West Antarctica has spatially confined events, while East Antarctica events are widespread. ERA5 data indicate that West Antarctica's extreme air temperature events are associated with consistent meridional atmospheric flows. Local to regional extreme warming events in East Antarctica are associated with inland high-pressure systems, which enhance katabatic winds. Localized warming events around complex coastal geographies appear to be related to mesoscale wind systems such as foehn but require further investigation using mesoscale numerical weather models. This work highlights the necessity for ongoing and new monitoring in regions where critical ecological and physical thresholds are being surpassed.