Tang et al. (2026) Unprecedented 2024 East Antarctic winter heatwave driven by polar vortex weakening and amplified by anthropogenic warming

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-04-01
• Authors: Haosu Tang, S. Li, Julie Jones, Sergi González, Andrew Orr, Friederike E. L. Otto, James A. Screen, Kyle R. Clem, Deniz Bozkurt, Jennifer L. Catto, Charlie C. Suitters, Michelle Maclennan, Y. Y. Sun
• DOI: 10.1038/s41612-026-01392-x

Research Groups

• School of Geography and Planning, University of Sheffield, Sheffield, UK
• WSL Institute for the Snow and Avalanche Research (SLF), Davos, Switzerland
• British Antarctic Survey, Cambridge, UK
• Grantham Institute, Imperial College, London, UK
• Department of Mathematics and Statistics, University of Exeter, Exeter, UK
• School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington, New Zealand
• Departamento de Meteorología, Universidad de Valparaíso, Valparaíso, Chile
• School of Electrical and Electronic Engineering, University of Sheffield, Sheffield, UK

Short Summary

This study investigates the unprecedented July-August 2024 East Antarctic winter heatwave, identifying polar vortex weakening as the primary driver and quantifying a significant amplification by anthropogenic warming, which increased its likelihood by more than twofold.

Objective

• To identify the physical drivers of the unprecedented July-August 2024 East Antarctic winter heatwave and quantify the anthropogenic contribution to its intensity and likelihood using a multi-model, multi-method attribution framework.

Study Configuration

• Spatial Scale: East Antarctica, with a focus on Dronning Maud Land (20°W–45°E, 90–70°S). Also includes Antarctic Peninsula, Southern Ocean, and polar cap (60°–90°S).
• Temporal Scale: Event period: July–August 2024. Satellite era: since 1979. Reanalysis data: 1979–2024. Climatological baseline: 1981–2010. CMIP6 historical simulations: 1850–2014, present-day climate: 2001–2020. Future projections: 2015–2100, end-of-century: 2081–2100.

Methodology and Data

• Models used:
  • Weather Research and Forecasting (WRF) model (regional, nudged to ERA5, pseudo–global warming framework).
  • Coupled Model Intercomparison Project Phase 6 (CMIP6) models (ACCESS-CM2, ACCESS-ESM1-5, CNRM-CM6-1, GFDL-ESM4 for attribution; Historical-CMIP6, HisNat-CMIP6, SSP2-4.5, SSP5-8.5 experiments).
  • Hadley Centre Global Environment Model version 3 (HadGEM3-A-N216) (atmosphere-only, large ensemble; Hist-HadGEM3, HisExt-2024, HisNatExt-2024 experiments).
• Data sources:
  • European Centre for Medium-Range Weather Forecasts Reanalysis version 5 (ERA5) (daily near-surface air temperature (T2m), precipitation, sea ice concentrations (SIC), outgoing longwave radiation (OLR), surface heat flux, specific humidity, water vapor flux, horizontal winds, geopotential heights).
  • Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) (daily atmospheric variables).
  • Research Data for Environmental and Antarctic Research (READER) dataset (in situ observations from Antarctic weather stations).
  • Observed sea surface temperature (SST) and sea ice concentration (SIC) for HadGEM3-A-N216.

Main Results

• During July–August 2024, East Antarctica experienced its most intense winter heatwave in the 46-year satellite era, with regional mean surface air temperatures across Dronning Maud Land (DML) exceeding the climatological mean by more than 9 °C for 17 consecutive days.
• Peak 2-meter air temperature (T2m) anomalies reached up to 27.5 °C (ERA5) and over 30 °C at some stations on 5 August.
• The heatwave was associated with anomalously heavy precipitation along the DML coast and reduced sea ice off DML.
• The 2024 DML heatwave had an estimated return period of approximately 1-in-135 years in reanalysis datasets.
• A pronounced weakening of the stratospheric polar vortex initiated a quasi-barotropic high-pressure anomaly, which enhanced meridional heat and moisture transport, accounting for approximately 50% of the observed surface warming. This weakening was linked to anomalous upward propagation of tropospheric planetary waves.
• Anthropogenic warming intensified the event by approximately 0.7 °C (mean magnitude shift across present-day attribution experiments).
• Anthropogenic warming more than doubled the likelihood of such exceptional winter heatwaves in the current climate (Probability Ratio of 2.6).
• Probabilistic attribution projects that the likelihood of such events increases from 2–3 times today to ~6 times under moderate emissions (SSP2-4.5) and up to 26 times under high emissions (SSP5-8.5) by 2100.
• Future projections suggest that 2024-like heatwaves would intensify by an additional 2.3 °C under SSP2-4.5 and 2.9 °C under SSP5-8.5 by the end of the 21st century relative to the pre-industrial period (storyline attribution).

Contributions

• Developed and applied a novel multi-model, multi-method attribution framework (integrating storyline, circulation analogues, and probabilistic approaches) to assess Antarctic extreme events, overcoming limitations of sparse data and high variability.
• Provided the first comprehensive assessment of both the physical mechanisms and the anthropogenic contribution to the unprecedented 2024 DML winter heatwave.
• Demonstrated that human-induced warming transformed what would have been a multi-century event under natural forcing into a centennial-scale occurrence in the present-day climate.
• Highlighted how human-induced warming is transforming even the coldest regions, with critical implications for ice shelf stability and the predictability of future Antarctic extremes.

Funding

• Natural Environment Research Council highlight topic grant PICANTE (NE/Y503290/1).
• Swiss National Science Foundation (SNSF) (project number 215406).
• Swiss National Supercomputing Centre (CSCS) (projects s1242, s1308).
• ANID-FONDECYT-1240190.
• ANID-FONDAP-1523A0002.
• COPAS COASTAL ANID FB210021.

Citation

@article{Tang2026Unprecedented,
  author = {Tang, Haosu and Li, S. and Jones, Julie and González, Sergi and Orr, Andrew and Otto, Friederike E. L. and Screen, James A. and Clem, Kyle R. and Bozkurt, Deniz and Catto, Jennifer L. and Suitters, Charlie C. and Maclennan, Michelle and Sun, Y. Y.},
  title = {Unprecedented 2024 East Antarctic winter heatwave driven by polar vortex weakening and amplified by anthropogenic warming},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01392-x},
  url = {https://doi.org/10.1038/s41612-026-01392-x}
}