Urgent cuts to global greenhouse gas emissions needed to avoid worst sea-level rise flooding in the UK, study shows Sadie Harley Scientific Editor Robert Egan Senior Editor 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 at risk of coastal flooding—a 25% increase compared with 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 risk 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 Professor 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 Agreement—to reduce future sea level rise and the need to adapt to unavoidable sea level rise in the coming decades." Rising seas reshape flood exposure The research showed sea levels are set to rise by between 0.4 and 0.6 meters (1.3 to 2 feet) across UK coastlines by 2100, resulting in a 13% increase in areas classified as at risk of coastal flooding. By 2300, these levels will triple to between 1.2 and 1.8 meters (4 to 6 feet), 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 modeling 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." A severe scenario for London 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 meters (49 feet) of sea level rise across the UK by 2300. This would result in extensive flood risk to critical infrastructure, including the M25 motorway and London's financial district, with large areas of west and north London under 1 meter (3.3 feet) of water during a severe coastal flood event.