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

Lucy M Bricheno,Judith Wolf

doi:10.1029/2018jc013866

Abstract

AbstractChanges 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 0.2 m is projected across most of the European coast. Increases in the annual maximum and 99th percentile wave height as large as 0.5–1 m 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.

Highlights

Coastal areas are the most densely populated on Earth—currently, with more than 35% of the world’s Gross Domestic Product and 40% of the population is located there (Rosen, 2000)
A dynamical downscaling approach has been used in this work, which combines an improved representation of the local coastline and bathymetry with higher-resolution wind forcing
A reduction in mean significant wave height (SWH) is not incompatible with an increase in extremes, rather, these results suggest that the probability density function (PDF) of wave heights may be widening

Summary

Introduction

Coastal areas (less than 100 m above sea level) are the most densely populated on Earth—currently, with more than 35% of the world’s Gross Domestic Product and 40% of the population is located there (Rosen, 2000). The Low Elevation Coastal Zone (less than 10 m above sea level) contains 10% of the world’s population and 13% of the world’s urban population (McGranahan et al, 2007). The relevant physical variables which can affect the coastline, potentially causing flooding and erosion in a warmer future climate, are global/regional sea level rise and changes in extreme sea levels, storminess, and waves. Large/long-period waves are the most damaging for overtopping (Palmer et al, 2014). Large short steep waves are most damaging for navigation, offshore fishing, and marine transport. We must examine changes in extreme waves as well as more typical conditions

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