Does ‘Blocking’ Shape the Future of Antarctic Heat Extremes?

2024 has been recorded as the hottest year in human history. Antarctica, already an ‘extreme’ environment, has been continuously witnessing unprecedented records in heat extremes in recent years. A record-shattering Antarctic heatwave in March 2022 highlights the importance of large-scale atmospheric circulations in the Southern Hemisphere (SH), such as atmospheric blocking. However, the presence of blocking patterns over the Antarctic continent is rarely discussed, often dismissed as 'too far south' to warrant attention.

This study examines the influence of SH blocking patterns on Antarctic heat extremes. We assess the ability of Community Earth System Model 2 (CESM2) to represent this complex relationship. Our findings suggest that SH blocking patterns exhibit elevated occurrences over the Antarctic Peninsula and East Antarctica. The future projections suggest a decline of SH blocking by 30% under SSP370 scenario by the end of the 21^st century. We explored the evolving relationship between blocking and heat extremes under a warming climate and found that the future decline in blocking occurrences is disproportionate to the corresponding changes in this relationship. This underscores that the role of blocking in future heat extremes will remain significant, especially due to the poleward expansion of the subtropics.