Millions projected to be at risk from sea-level rise in the continental United States

• Published in: Nature climate change 2016-07, Vol.6 (7), p.691-695
• Main Authors: Hauer, Mathew E., Evans, Jason M., Mishra, Deepak R.
• Format: Article
• Language: English
• Subjects: 704/106/694/2739; 704/844/2739; 706/689/523; 706/689/694/2739; 706/689/694/2786; Adaptation; Censuses; Climate Change; Climate Change/Climate Change Impacts; Datasets; Economic impact; Environment; Environmental Law/Policy/Ecojustice; Floods; letter; Marine; Population growth; Sea level
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/nclimate2961

Ongoing population growth could greatly exacerbate the human impact of sea-level rise in coastal areas of the continental US this century, with the potential to induce mass population movements unless protective measures are taken. Sea-level rise (SLR) is one of the most apparent climate change stressors facing human society 1 . Although it is known that many people at present inhabit areas vulnerable to SLR 2 , 3 , few studies have accounted for ongoing population growth when assessing the potential magnitude of future impacts 4 . Here we address this issue by coupling a small-area population projection with a SLR vulnerability assessment across all United States coastal counties. We find that a 2100 SLR of 0.9 m places a land area projected to house 4.2 million people at risk of inundation, whereas 1.8 m affects 13.1 million people—approximately two times larger than indicated by current populations. These results suggest that the absence of protective measures could lead to US population movements of a magnitude similar to the twentieth century Great Migration of southern African-Americans 5 . Furthermore, our population projection approach can be readily adapted to assess other hazards or to model future per capita economic impacts.