Follow us on Google News (click on ☆)
This is the first large-scale, building-by-building assessment of the long-term impacts of 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 the number of buildings that would be flooded according to sea level rise over several centuries.
"Sea level rise is a slow but inevitable consequence of global warming. It's already affecting coastal populations, and it will continue for centuries," says Professor Natalya Gomez, co-author of the study and holder of the Canada Research Chair in Ice Sheet-Sea Level Interactions at McGill University. "We often talk about sea level rise of a few tens of centimeters, or even one meter, but in reality, the sea could rise by several meters if we don't quickly stop burning fossil fuels."
Millions of buildings threatened, even in the best-case scenario The research team studied scenarios predicting sea level rise between 0.5 and 20 meters. They found that with a rise of only 0.5 meters (about 1.6 feet), a level expected to be reached even if emissions are significantly reduced, approximately three million buildings could be flooded. In scenarios predicting a rise of five meters (about 16.4 feet) or more, which could occur within a few hundred years if emissions don't stop quickly, the risks increase sharply and over 100 million buildings would be threatened.
Many of these buildings are located in densely populated, low-lying areas, meaning entire neighborhoods and critical infrastructure, including ports, refineries, and heritage sites, would be affected.
In figure (a), the color of each 50 km grid cell represents the sea level rise (SLR) that causes flooding of more than 25% of the total number of buildings in the cell at high tide. The insets show regions of approximately 3 km (b) and 250 m (c).
In (b) and (c), the color of each building depends on the SLR value at which its ground level comes into contact with water at high tide. These figures show that, despite the relatively coarse resolution of the overall grid result in (a), the variability within a single cell can be significant and is well reflected by the data.
"We were surprised to find the large number of buildings threatened by a relatively modest long-term sea level rise," admits Professor Jeff Cardille, co-author and professor at McGill University. "Some coastal countries are much more threatened than others due to coastal topography and building locations."
Crucial information for urban planners, policymakers, and communities According to the researchers, these findings are valuable for urban planners, policymakers, and communities preparing for the inevitable sea level rise.
"We will all be affected by climate change and sea level rise, whether we live near the ocean or not," says Professor Eric Galbraith, who also participates in the study at McGill University. "We all depend on goods, food, and fuels that pass through ports and coastal infrastructure vulnerable to sea level rise. The disruption of these essential infrastructures could have disastrous consequences for economies and global food systems."
The study's interactive map, publicly accessible via Google Earth Engine, allows decision-makers to visualize the most threatened regions. This data can be used to develop climate change adaptation strategies, such as building protective infrastructure, planning land use, or, in some cases, relocating activities and assets.
"It's impossible to escape at least a moderate sea level rise," specifies Maya Willard-Stepan, the lead author, who conducted the study as part of an undergraduate research project. "The earlier coastal communities start preparing for it, the better their chances of continuing to thrive."
The study The article "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 and E. M. Bennett, was published in npj Urban Sustainability.