Losing coastal plant communities to climate change will weaken sea defences

Typical flowering plants on sand dunes on the Spanish coast.
Credit: Mick Hanley, University of Plymouth

Coastal plant communities are a crucial element of global sea defences but are increasingly threatened by the human-induced effects of climate change, according to new research.

Rising sea levels and the increased frequency and intensity of extreme storm events are having a visible, global impact on beaches, cliff faces and coastal infrastructure.

But a new report suggests their impact on coastal , an integral part of shoreline defences, needs to be placed in greater focus.

The research was led by the University of Plymouth, in conjunction with scientists at Utrecht University and Manchester Metropolitan University, and is published in a special edition of the journal Annals of Botany.

It follows a recent assessment by the Intergovernmental Panel on Climate Change (IPCC 2019), which asserted that anthropogenically-driven  poses a severe environmental threat to estuarine and coastal ecosystems.

This report not only reviews how the flood and erosion threats posed by a combination of sea level rise and storms can affect coastal sub-, inter- and supra-tidal plant communities, but also highlights the contribution that habitats like saltmarshes, mangrove forests, sand dunes and kelp beds make to coastal protection.

Dr. Mick Hanley, Associate Professor (Reader) in the School of Biological and Marine Sciences at the University of Plymouth, led the research. He said: “It has been suggested that by 2050, it could cost well over $50billion to protect the world’s largest cities from coastal flooding. In contrast, coastal vegetation can offer natural protection against erosion and flooding for a fraction of the costs associated with constructing so-called hard defences like concrete walls. Society is only just beginning to appreciate this, but estuarine and coastal ecosystems can be integrated into a dynamic, low-cost flood defence strategy to meet the ever increasing challenges posed by rising sea-levels and storms.”

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