Up to 410 million people will be living in areas less than 2 metres above sea level, and at risk from sea level rises, unless global emissions are reduced, according to a new studypublished in Nature Communications.
Currently, 267 million people worldwide live on land less than 2 metres above sea level. Using a remote sensing method called Lidar, which pulsates laser light across coastal areas to measure elevation on the Earth’s surface, the researchers predicted that by 2100, with a 1 metre sea level rise and zero population growth, that number could increase to 410 million people.
Their maps showed that 62% of the most at-risk land is concentrated in the tropics, with Indonesia having the largest extent of land at risk worldwide. These projections showed even more risk in the future, with 72% of the at-risk population in the tropics, and 59% in tropical Asia alone.
Dr Aljosja Hooijer, specialist water resources expert for Deltares, an independent institute for applied research in water and subsurface, and the lead author of the study, said while the research was inherently uncertain, more focus was needed on tropical regions for long-term flood preventions.
He said: “There’s a lot of scientists looking at long-term scenarios. But it’s happening now in parts of the world, and in these parts of the world, mostly in the tropics. And not just in south-east Asia, it’s also for instance in the Niger delta and Lagos.
“If you look at sea level rise, the impact research to date is mostly focused on defining sea level rise scenarios. There has been relatively little attention to elevation data, and that is simply because people didn’t feel much could be done about it, including ourselves for a long time.”
Maarten van Aalst, professor in climate and disaster resilience, and a contributing lead author to the Intergovernmental Panel on Climate Change (IPCC) said: “These numbers are another wake-up call about the immense number of people at risk in low-lying areas, particularly in vulnerable countries in the global South..."
Dr Sally Brown, deputy head of life and environmental sciences at Bournemouth University, said: “This research shows once again that many millions of people around the world are living in areas of flood risk. Sea-level rise increases the threat of flooding, which could have particularly severe impacts for communities and people’s livelihoods in developing nations.”