As well as providing renewable energy, wave farms can help protect coasts against erosion by reducing the force of waves. However, it remains unknown whether they can provide this complementary service under future climate change when sea levels will be higher. A new study, based upon computer simulations, concludes that a wave farm off the south coast of Spain could indeed protect the coastline under higher sea levels, and cause the local beach to grow in size after storms.

Future sea-level rise threatens coasts across the world by increasing the risk of coastal erosion and flooding. Coasts near river deltas are particularly affected, as they are often home to places with high economic, social and environmental value. Although primarily built to supply energy, wave farms can also protect coasts by softening the impact of waves as they roll towards the shore. This EU-funded study1 is the first to explore how wave farms could affect coastlines under future sea-level rise. The researchers considered the effects of a hypothetical wave farm 500–750 metres off the coast of Playa Granada, a three-km-long beach in southern Spain. This gravelly beach has suffered shoreline retreat and terminal erosion in recent years. It experiences Atlantic cyclones and Mediterranean storms, during which significant wave heights typically exceed three metres. Using two computer models, the researchers simulated the wave farm’s effects on wave heights and sediment movement under three scenarios: 1. Present-day sea levels; 2. Optimistic future sea levels in 2100 — assuming climate change will develop as per scenario RCP4.5, under which global warming stabilises thanks to major reductions in carbon emissions; 3. Pessimistic future sea levels in 2100 — assuming the business-as-usual, high emission climate change scenario of RCP8.5, which projects continued global warming.

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