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

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Abstract

Sea-level rise (SLR) is one of the most apparent climate change stressors facing human society1. Although it is known that many people at present inhabit areas vulnerable to SLR2,3, few studies have accounted for ongoing population growth when assessing the potential magnitude of future impacts4. 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-Americans5. Furthermore, our population projection approach can be readily adapted to assess other hazards or to model future per capita economic impacts.

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Figure 1: Cumulative projected at-risk populations for the continental United States, 2010–2100.
Figure 2: Projected cumulative populations at risk of sea-level rise in 2100 under the 1.8 m scenario.
Figure 3: Cumulative projected populations at risk of SLR under the 0.9 m scenario by 2100 for US counties.

Change history

  • 21 March 2016

    In the version of this Letter originally published online, the data in columns 2, 3, 4 and 6 in Table 1 was found to be incorrect for the state of Louisiana. The data and their corresponding totals have been amended in Table 1 and Figure 2. This has been corrected in all versions of the Letter.

  • 22 April 2016

    In the version of the Letter originally published, the values for current estimates of populations at risk of 3 ft and 6 ft of sea-level rise were incorrect, affecting data in Table 1 and Fig. 2, as well as two sentences in the main text. These have all been corrected in all versions of the Letter.

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Acknowledgements

Publication supported in part by an Institutional Grant (NA10OAR4170098) to the Georgia Sea Grant College Program from the National Sea Grant Office, National Oceanic and Atmospheric Administration, US Department of Commerce. Data reported in the paper are available in the Supplementary Methods. The authors are grateful for the assistance and constructive comments from K. Devivo, C. Hopkinson, J. M. Shepherd, S. Holloway, T. Mote, J. Baker and W. Anderson.

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M.E.H. produced the small-area population projections and the projections of inundation, contributed to the methodological design, wrote the paper, and is the corresponding author to whom requests for materials should be addressed. J.M.E. contributed significantly to the methodological design, conceptual framing, and editing of the paper. D.R.M. produced the inundation modelling for Louisiana and contributed to the editing of the paper.

Corresponding author

Correspondence to Mathew E. Hauer.

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The authors declare no competing financial interests.

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Hauer, M., Evans, J. & Mishra, D. Millions projected to be at risk from sea-level rise in the continental United States. Nature Clim Change 6, 691–695 (2016). https://doi.org/10.1038/nclimate2961

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