Future response of global coastal wetlands to sea-level rise, Schuerch et al. 2018

The vulnerability of coastal wetlands to sea-level rise is disputed, with some researchers predicting most will be flooded out of existence by the end of the 21st Century. Coastal wetlands provide critical ecosystem services, including protection from storm surges, water quality improvement, fisheries habitat and carbon sequestration. By accounting for the enhancement of sediment build-up when storms are more frequent and more severe and for the possibility of “accommodation space” for coastal wetlands to move inland, however, these authors reach a more optimistic conclusion. (Sediment build-up, or accretion, allows coastal wetlands to grow vertically, potentially remaining at a higher elevation than sea-level.) They estimate that:

Rather than losses, wetland gains of up to 60 per cent of the current area are possible, if more than 37 per cent (our upper estimate for current accommodation space) of coastal wetlands have sufficient accommodation space, and sediment supply remains at present levels [Schuerch 2018: 231].  

This is an important ecosystems restoration message because it means humans can directly influence the persistence of coastal wetlands, and thus the continuation of the essential ecosystem services they provide.

Our simulations suggest that the resilience of global wetlands is primarily driven by the availability of accommodation space, which is strongly influenced by the building of anthropogenic infrastructure in the coastal zone and such infrastructure is expected to change over the twenty-first century. Rather than being an inevitable consequence of global sea-level rise, our findings indicate that large-scale loss of coastal wetlands might be avoidable, if sufficient additional accommodation space can be created through careful nature-based adaptation solutions to coastal management [Schuerch 2018: 231].

The authors describe specific solutions to protect coastal wetlands, which they recommend be implemented at a large, regional or landscape scale.

Existing nature-based adaptation solutions that allow coastal wetlands to migrate inland include the inland displacement of coastal flood defenses (typically along highly engineered coastlines) or the designation of nature reserve buffers in upland areas surrounding coastal wetlands. These schemes, however, are currently implemented as local-scale projects only; strategically upscaling such projects, for example, as suggested by the shoreline management plans in England and Wales or the coastal master plan in Louisiana, may help coastal wetlands adapt to SLR [sea level rise] at the landscape scale and protect rapidly increasing global coastal populations [Schuerch 2018: 234].