- There has been a poleward shift in the storm track since the 1990s and an increase in the annual mean number of storms.
- Mean significant wave height has reduced over the last 30 years to the north of the UK and increased to the south.
- Observed trends in storms and waves cannot be directly attributed to climate change because of the high variability and limited understanding of mechanisms.
High evidence, medium consensus
While our evidence base has continued to grow, with longer observational datasets and more model reanalysis available, there is not a consensus in the trend in SWH, which is highly sensitive to seasonality and short-term variability. No dataset or reanalysis is perfect and it is unclear which of those currently available for wave climate is the most reliable.
- Climate change could affect storms and waves in the North Atlantic, but natural variability will continue to dominate over the next few decades.
- The most severe waves could increase in height by 2100 under a high-emissions scenario, but there could be an overall reduction in mean significant wave height in the North Atlantic.
- Projections suggest the wintertime storm track could intensify over the UK.
- The chance of severe storms reaching the UK during autumn may increase if tropical cyclones (such as hurricanes) become more intense, and their region of origin expands northwards.
Medium evidence, low consensus
The future changes depend on model projections, which have improved on moving from CMIP5 to CMIP6 but still have shortcomings when representing the most intense storms. There are still quite substantial differences between different climate models, but new higher-resolution models promise better representation of storms. Meta-analysis through e.g. COWCLIP has led to better understanding and quantification of intra-model uncertainty, and helped identify areas of (no) consensus.
- Inconsistency between models, in-situ observations, and remotely sensed wave data.
- Improve the simulation of storms in climate models.
- Improve understanding of how North Atlantic storms and blocks respond to external forcing.
- Uses of new techniques: meta-analysis and statistical methods to reduce historic and future uncertainty