Coastal retreatClimate change: we need to start moving people away from some coastal areas, warns scientist

By Luciana Esteves

Published 19 September 2018

Climate change has forced a paradigm shift in the way coastal flooding and erosion risks are managed. In areas of lower risk, adaptation plans are being devised, often with provisions to make properties and infrastructure more resilient. Adaptation may involve requiring raised foundations in flood-prone areas or the installation of mitigating measures, such as sustainable drainage systems. Building codes may also be established to make structures more disaster-proof and to control the types of constructions within risk zones. But such adaptation options are often of limited use or unsuitable for high-risk areas. In such areas relocation is the only safe climate-proof response.

We are all too familiar with images of flooding in low lying areas after heavy rainfall or houses destroyed by coastal erosion after a storm. For an increasing number of people, coastal flooding and erosion is a real threat to property, the local economy and, in some cases, life. Hurricane Florence, for example, is forcing more than a million people on the US East Coast to flee from their homes.

Coasts support important industries (such as ports and tourism) and their populations are growing faster than inland areas. But coastal areas are also particularly sensitive to impacts of climate change, which are likely to increase the extent, intensity and frequency of coastal flooding and erosion.

So not only have we occupied areas that naturally flood and erode from time to time, we have changed the environment in ways that increase coastal flooding and erosion risk. And we continue to do so, sometimes with serious legal consequences. Meanwhile, public policies have not been very effective in managing this predicament.

Traditional hard engineering approaches of coastal protection (such as groynes, revetments and seawalls) are known to cause detrimental effects, which in the longer term can aggravate the problem they were supposed to solve. The impact of Hurricane Katrina in New Orleans was a stark reminder that engineering structures are not effective against all events at all times. They are built based on trade-offs between the level of protection needed and the costs of construction and maintenance.

Soft engineering, such as beach nourishment (where sediment, usually sand, is added to the shore), can offer a level of protection and beach amenity – but these reduce through time, as erosion continues. Meanwhile, “protection” gives a false sense of safety and enables occupation of risk areas, increasing the number of people and assets in risk areas.