Future Wave Conditions of Europe, in Response to High-End Climate Change Scenarios

Changes in future North Atlantic storminess will impact upon wave conditions along the European coasts, with implications for coastal erosion, overtopping, and flood risk. In this study we make a detailed analysis of historic and future wave conditions around the European Atlantic coast, making projections out to the year 2100 under Representative Concentration Pathways 4.5 and 8.5 future emissions scenarios. A decrease in mean significant wave height of the order 0.2m is projected across most of the European coast. Increases in the annual maximum and 99th percentile wave height as large as 0.5-1m are observed in some areas but with a more complex spatial pattern. An increase in waves to the north of Scotland is also observed, mainly caused by a reduction in sea ice. We generate a set of coastal wave projections at around 10-km resolution around continental Europe, Ireland, and the British Isles. Widening of the probability density function (PDF) is observed, suggesting an increased intensity of rare high wave events in the future. The emergent signal of a reduced mean wave height is statistically robust, while the future changes in extreme waves have a wider confidence interval. An assessment of different extreme waves metrics reveals different climate change response at very high percentiles; thus, care should be taken when assessing future changes in rare wave events. Plain Language Summary Waves are important to shipping, coastal flooding, and erosion. A numerical model of waves was built and tested for skill in representing historic waves, by comparing against observations at buoys. Climate model winds were then used to drive a model of sea surface waves. The future projections show a decrease in average wave height but increases in the maximum waves. The statistical method used to measure extreme waves seen during storms can affect the conclusion. We see evidence that the mean can go down, while the extremes increase in future.