Atmospheric Blocking Influences on Climate Variability

Atmospheric blocking refers to persistent high-pressure systems that disrupt the typical west-to-east progression of mid-latitude westerly winds. These quasi-stationary anticyclones alter large-scale circulation, leading to prolonged periods of anomalous weather such as heatwaves, cold spells, droughts or heavy rainfall. Blocking events can modify storm tracks, amplify teleconnection patterns and interact with processes such as Arctic amplification and sea-ice loss. Their occurrence varies seasonally and regionally, with key hotspots over Greenland, Scandinavia and the Pacific. By anchoring Rossby wave ridges, blocking alters the distribution of temperature and precipitation, affects jet-stream position and modulates low-frequency climate variability on timescales from days to seasons. Improved detection and understanding of blocking dynamics are vital for predicting extreme events and assessing climate-change impacts.

Research from Nature Portfolio

One recent study has demonstrated two synergistic mechanisms by which Arctic warming and reduced spring snow cover enhance summer blocking over Greenland. First, amplified high-latitude warming weakens the meridional temperature gradient, producing a wavier mid-latitude flow that favours more frequent Greenland anticyclones. Second, diminished North American spring snow cover triggers a stationary Rossby-wave response, reinforcing a persistent ridge over Greenland. Together, these processes explain the recent rise in Greenland blocking and its role in accelerating ice-sheet mass loss.

Research from all publishers

An advanced Markov state modelling approach has been applied to daily 500 hPa geopotential-height fields to detect dominant winter weather regimes across the Northern Hemisphere. By identifying slowest-decaying dynamical modes, this work reveals transitions between zonal flow and blocking regimes in both Atlantic and Pacific sectors, and uncovers simultaneous Atlantic-Pacific blocking patterns with a strong dynamical foundation that transcends classical empirical methods.

A comprehensive review of Euro-Atlantic blocking highlights the physical pathways linking anticyclone persistence to temperature and precipitation extremes. In summer, subsidence beneath blocking ridges yields clear skies, strong radiative warming and drought, while winter blocking drives cold spells through meridional advection of Arctic air. The review emphasises the importance of upper-level phasing, compound events and the challenges in predicting blocking onset and decay under climate change.

Sensitivity experiments with a coupled ocean-atmosphere model under reduced Atlantic Meridional Overturning Circulation (AMOC) show that weaker overturning intensifies the North Atlantic temperature gradient and strengthens the jet stream. As a result, blocking frequency decreases, leading to fewer winter cold spells over Europe despite overall cooling. These findings underline how large-scale ocean circulation changes can modulate blocking and associated extreme-event risk.

Atmospheric Blocking Influences on Climate Variability publication trend

The graph below shows the total number of articles in atmospheric blocking influences on climate variability across all publications each year (not limited to Nature Index journals).

Technical terms

Atmospheric blocking: A quasi-stationary high-pressure system that interrupts prevailing westerly winds and redirects large-scale flow.

Rossby wave: A large-scale meandering atmospheric wave driven by the earth’s rotation and latitudinal temperature gradients.

Teleconnection: A climate anomaly related to remote atmospheric or oceanic disturbances, linking weather patterns across large distances.

Geopotential height: The altitude of a pressure surface in the atmosphere, commonly used to identify ridges and troughs in mid-latitude flow.

Anticyclone: A high-pressure weather system characterised by descending air, clear skies and often associated with warm, dry conditions.

References

1. Summer atmospheric circulation over Greenland in response to Arctic amplification and diminished spring snow cover. Nature Communications (2023).
2. Unsupervised detection of large-scale weather patterns in the northern hemisphere via Markov State Modelling: from blockings to teleconnections. npj Climate and Atmospheric Science (2024).
3. Atmospheric blocking and weather extremes over the Euro-Atlantic sector – a review. Weather and Climate Dynamics (2022).
4. Extreme cold events in Europe under a reduced AMOC. Environmental Research Letters (2023).