A pioneering study has revealed that by the turn of the next century at least half a million more people in the UK will be exposed to risk of coastal flooding – a 25% increase compared to now.
The research, led by the Met Office and the University of Bristol, quantifies for the first time the scale of the UK population at threat from coastal flooding under future sea-level rise projections.
Even if current global carbon emissions pledges are met, around 1.4 million more people in the UK look set to be affected by coastal flooding risk by 2200. This rises to 1.7 million by 2300, according to the study published in Nature Communications.
Study lead author Prof Matt Palmer , Professor of Climate Science at the University of Bristol Cabot Institute for the Environment and Met Office Science Fellow, said: "The oceans and ice-covered parts of the world respond very slowly to global warming, which makes sea-level rise the 'sleeping giant' of climate change. The result is that sea-level rise is 'locked-in' for centuries to come; our study quantifies the scale of the adaptation challenge and highlights how reducing greenhouse gas emissions can help avoid the worst outcomes.
"The findings highlight the importance of global action on emissions – as set out in the Paris Climate Agreement – to de-risk future sea level rise and the need to adapt to unavoidable sea-level rise in the coming decades."
The research showed sea-levels are set to rise by between 0.4 and 0.6 metres across UK coastlines by 2100, resulting in a 13% increase in areas classified as at risk of coastal flooding. By 2300, these levels triple to between 1.2 and 1.8m, with coastal flood risk areas growing by more than half (56%).
Drawing on findings from the United Nations Intergovernmental Panel on Climate Change (IPCC), the researchers combined UK-tailored sea-level projections with an industry-leading UK dynamic flood model developed by Fathom , based in Bristol.
This allowed them to explore a wide range of possible sea-level rise scenarios and quantify the increase in population at risk from coastal flooding over this and subsequent centuries.
Study co-author Dr James Savage, Head of Flood Modelling at Fathom, said: "As you would expect, the low-lying areas will be hit hardest by sea-level rise. The Wash and the Humber Estuary stand out as 'hot spots' for future coastal flood risk across all scenarios."
The research also considers a 'reasonable worst-case scenario' for sea-level rise that includes controversial ice sheet instability processes, which would see more than 15 m of sea-level rise across the UK by 2300. This would result in extensive flood risk to critical infrastructure, including the M25 motorway and the financial district of London, with large areas of west and north London under 1m of water during a severe coastal flood event.
The study emphasises the need to monitor ongoing sea-level rise with a particular focus on ice sheets. This would allow as much time as possible to detect and react to future changes that could indicate more extreme future sea-level rise. It also highlights the potential to mitigate the worst sea-level rise outcomes through rapid and deep reductions in global greenhouse gas emissions.
Study co-author Prof Jeffrey Neal , Professor of Hydrology at the University of Bristol and Chief Scientific Advisor at Fathom, said: "The worst-case sea-level rise outcomes would pose massive challenges for the UK in the coming centuries and the need for large-scale movement of populations and settlements away from the coast.
"But there is also huge potential to avoid these outcomes by pursuing concerted global efforts to reduce greenhouse gas emissions, in line with the Paris Agreement goals."
