Graversen et al. (2025) Enhanced weather persistence due to amplified Arctic warming

Identification

• Journal: Communications Earth & Environment
• Year: 2025
• Date: 2025-12-09
• Authors: Rune Grand Graversen, Rachel H. White, Timo Vihma
• DOI: 10.1038/s43247-025-03050-1

Research Groups

• Department of Physics and Technology, UiT The Arctic University of Norway, Tromsø, Norway
• Norwegian Meteorological Institute, Tromsø, Norway
• Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
• Finnish Meteorological Institute, Helsinki, Finland

Short Summary

This study provides observational evidence that weather persistence, in terms of surface-air temperature anomalies, has increased in the Northern Hemisphere mid-latitudes during recent decades, directly linking this change to amplified Arctic warming and a consequent weakening of mid-latitude westerly atmospheric flow.

Objective

• To robustly confirm if a change in weather persistence is occurring in the Northern Hemisphere mid-latitudes and, if so, to investigate its linkage to meridional differences in the pace of global warming, specifically amplified Arctic warming.

Study Configuration

• Spatial Scale: Northern Hemisphere mid-latitudes (primarily 30°–60° N, with averages over 45°–70° N for some analyses) and the Arctic (north of 60° N).
• Temporal Scale: Data period from 1979–2023. Trends analyzed between two 15-year periods (1980–1994 and 2008–2022). Seasonal-scale events defined as 3 consecutive months. Data resolutions include 6-hourly, daily, and monthly.

Methodology and Data

• Models used: No explicit climate models were used for the primary analysis; the study relies on reanalysis data and statistical methods.
• Data sources: ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecast (ECMWF), including Surface Air Temperature (SAT), Geopotential Height (GPH) at 500 hPa, and zonal mass flux (uM).

Main Results

• Weather persistence, defined as the duration of surface-air temperature anomalies lasting three days or longer, has significantly increased in large parts of the Northern Hemisphere mid-latitudes since 1980.
• This increase in persistence is strongly associated with amplified Arctic warming, which reduces the meridional temperature gradient and subsequently weakens the 500 hPa GPH gradient and the westerly zonal atmospheric mass flux (uM) in the mid-latitudes.
• A significant negative spatial correlation (e.g., Pearson correlation r = -0.66, p < 0.01 for full year) is observed between changes in persistence and uM over the mid-latitudes, indicating that reduced zonal mass flux leads to increased temperature persistence.
• Day-lag composite and regression analyses demonstrate that a warm Arctic, relative to mid-latitudes, induces a near-instantaneous decrease in mid-latitude zonal mass flux, followed by a subsequent increase in temperature persistence.
• Seasonal analysis reveals similar patterns in winter, with reduced uM leading to increased long-lasting cold anomalies over northern mid-latitude continents. In summer, while Arctic warming is weaker, reduced uM is linked to more long-lasting warm anomalies.

Contributions

• Provides robust observational evidence of a significant increase in temperature persistence across all weather types and seasons in the Northern Hemisphere mid-latitudes over recent decades.
• Establishes a clear physical link between this observed increase in weather persistence and amplified Arctic warming, mediated by a weakening of the mid-latitude westerly atmospheric flow.
• Utilizes a broad, non-parametric metric of persistence that captures changes across a wider range of timescales than previous studies focused on specific weather types or seasons.
• Highlights the critical implications of increased weather persistence for amplifying climate change impacts, including more frequent and intense extreme weather events (heatwaves, cold spells), and potential consequences for biodiversity and global food supply.

Funding

• University of Tromsø (UiT)
• Natural Sciences and Engineering Research Council of Canada (NSERC) [RGPIN-2020-05783]
• Research Council of Finland (contract 362776)
• Sigma2 – the National Infrastructure for High Performance Computing and Data Storage in Norway (projects: NN9348k and NS9063k)

Citation

@article{Graversen2025Enhanced,
  author = {Graversen, Rune Grand and White, Rachel H. and Vihma, Timo},
  title = {Enhanced weather persistence due to amplified Arctic warming},
  journal = {Communications Earth & Environment},
  year = {2025},
  doi = {10.1038/s43247-025-03050-1},
  url = {https://doi.org/10.1038/s43247-025-03050-1}
}