Sea level rise could put more than 100 million buildings across the Global South at risk of regular flooding if fossil fuel emissions are not curbed quickly, according to a new McGill-led study published in npj Urban Sustainability.
The research provides the first large-scale, building-by-building assessment of the impact of long-term sea level rise on coastal infrastructure in Africa, Southeast Asia and Central and South America. The team used detailed satellite maps and elevation data to estimate how many buildings would be inundated at various levels of sea level rise over multi-century timescales.
"Sea level rise is a slow, but unstoppable consequence of warming that is already impacting coastal populations and will continue for centuries," said Prof. Natalya Gomez, co-author of the study and Canada Research Chair in Ice Sheet-Sea Level Interactions at McGill University. "People often talk about sea level rising by tens of centimetres, or maybe a metre, but in fact it could continue to rise for many metres if we don't quickly stop burning fossil fuels."
Millions of buildings at risk, even in best-case scenario
The study considered scenarios of between 0.5 and 20 metres of sea level rise. It found that with a rise of just 0.5 metres, a level projected to occur even under ambitious emissions cuts, approximately three million buildings could be inundated. Under scenarios with five metres or more of rise, as could be expected within a few hundred years if emissions don't end soon, exposure increases sharply, with over 100 million buildings at risk.
Many of these buildings are in densely populated, low-lying areas, meaning that entire neighbourhoods and critical infrastructure, including ports, refineries and cultural heritage sites, would be affected.
"We were surprised at the large number of buildings at risk from relatively modest long-term sea level rise," said Prof. Jeff Cardile, coauthor and professor at McGill University. "Some coastal countries are much more exposed than others, due to details of the coastal topography and locations of buildings."
Critical insights for urban planners, policymakers, communities
The researchers argue that these findings offer critical insights for urban planners, policymakers and communities working to prepare for inevitable sea level rise.
"Every one of us will be affected by climate change and sea level rise, whether we live by the ocean or not," said Eric Galbraith another professor involved in the study at McGill. "We all rely on goods, foods and fuels that pass through ports and coastal infrastructure exposed to sea level rise. Disruption of this essential infrastructure could play havoc with our globally interconnected economy and food system."
The study's interactive map, publicly available via Google Earth Engine, allows decision-makers to visualize which regions face the greatest exposure. This data can inform climate adaptation strategies such as building protective infrastructure, adjusting land use planning or, in some cases, managed retreat.
"There is no escaping at least a moderate amount of sea level rise," said Maya Willard-Stepan, lead author who conducted the study as part of an undergraduate research project . "The sooner coastal communities can start planning for it, the better chance they have of continuing to flourish."
About the study
Assessing the exposure of buildings to long-term sea level rise across the Global South by M. Willard-Stepan, N. Gomez, J. A. Cardille, E. D. Galbraith & E. M. Bennett was published in npj Urban Sustainability.
