Blog: Managing our heritage coastline with a changing climate
Climate change scientists mostly talk about large numbers and the global effects of climate change. Locally understanding the impact of climate change and its effects on organisations and individuals is important too. Over the past few months I have been assessing for the National Trust how much of its coastal land is located in flood risk zones in England and Wales.
The National Trust is a charity who cares for national heritage and naturein perpetuity England, Wales and Northern Ireland. Founded in 1895, the Trust has a long-term vision to ensure our heritage is kept special for ever, for everyone. For me, this has meant focusing on coastal heritage.
The longevity of the Trust uniquely enables it to be in a strong position to plan for climate change. The Trust has a vested interest over decadal or even centennial timescales. This means they can think ahead and plan today for changing conditions. At their coastline locations, this means preparation for sea-level rise, which is rising at about 3mm/yr. Additionally, land in the east and south of England and parts of Wales is sinking making the situation more challenging.
The National Trust owns 775 miles of coastline in England, Wales and Northern Ireland, including 20.3 km2 of low-lying saltmarsh and 15.4km2 of potentially erodible sand dunes. The Trust seeks to understand sea-level risk and wider coastal change, now and change in the future.
I found that 2.6% of National Trust land in England and Wales is at risk from coastal flooding - up to a 1-in-200 year extreme event. A 1-in-200 year event is fairly usual, particularly as flood defences are not taken into account. That compares with an average in England and Wales of 4.4%. A 1-in-200 year event does not mean a storm may occur once every 200 years. Indeed, two 1-in-200 year events may occur in subsequent winters, and then not occur for 198 years. However, with sea-level rise, flooding is projected to occur more frequently, so extreme flooding may be seen more often.
Nearly half of National Trust land at risk from coastal flooding is located in the east of England. That’s because the National Trust owns low-lying sections of the coast, such as Orford Ness, a spit used for military activities, and Blakeney National Nature Reserve, with its beautiful landscape and wildlife. This doesn’t mean that with sea-level rise that these low-lying areas and others will drown.
Coasts change naturally and accrete sediment, and some of the coastal landforms that the National Trust own have been there hundreds of years. That’s part of the beauty of heritage coasts: They have been there and seen change and survived, and what we seen of them now is just one part of a long story, and one for hopefully many years to come.
The National Trust considers its position of managing the coast and the threat to areas, such as storms, through its Shifting Shores programme, which is now in its 13th year. Shifting Shores advocates working with natural processes and adapting to coastal change, including sea-level rise. If we do not do so, we risk storing up problems for the future, which may be worse than if we had acted to do. This is a bold step: Many people are uncomfortable with change, but as the coast changes and responds to sea-level rise, so do we.
Over this century, national non-statutory coastline management policies (which the National Trust follow) will shift away from holding the line of a defended engineered coast, to one of managed realignment, where the coast is deliberately realigned to accommodate the sea. The vast majority of cities and towns will continue to be defended, but rural coastlines (including those which contain heritage) will often be allowed to realign. For the National Trust, this means over the next 100 years changing its coastal management strategy in some locations from a policy of holding the line to one of managed realignment or no active intervention through engineering or other means.
Accepting coastal change isn’t easy, and neither is the science of analysing it. Sea-level rise is just one of many issues that need to be considered for managing heritage coasts and communities. The National Trust is well equipped for this long-term challenge as it tackles a global-scale problem locally, making small changes today, to prepare or avoid for larger or unanticipated changes in the future. This means we can all enjoy our heritage coast with greater long-term prosperity for years to come.
Sally Brown is a senior researcher for the Tyndall Centre at the University of Southampton