Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

Barbara Neumann,Robert J Nicholls,Juliane Zimmermann,Athanasios T Vafeidis,Lalit Kumar

doi:10.1371/journal.pone.0118571

Barbara Neumann, Robert J Nicholls + Show 3 more

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https://doi.org/10.1371/journal.pone.0118571

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Journal: PloS one	Publication Date: Mar 11, 2015
Citations: 1687	License type: CC BY 4.0

Affiliation: Kiel University, Tyndall Centre, University of Southampton

Abstract

Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we identify needs for further research and scope for improvement in this kind of scenario-based exposure analysis.

Highlights

Coastal zones have always attracted humans because of their rich resources, their supply of subsistence resources; for logistical reasons, as they offer access points to marine trade and transport; for recreational or cultural activities; or because of their special sense of place at the interface between land and sea
Population density is significantly higher in coastal than in non-coastal areas [1, 2] and there is an ongoing trend of coastal migration, which is associated with global demographic changes [3]
Our results suggest a growth of the population in the low-elevation coastal zone (LECZ) from 625 million to between 879 million and 949 million people in the year 2030 (Table 4 and Table 5; Fig. 2; S3 Table)

Summary

Introduction

Coastal zones have always attracted humans because of their rich resources, their supply of subsistence resources; for logistical reasons, as they offer access points to marine trade and transport; for recreational or cultural activities; or because of their special sense of place at the interface between land and sea. Coastal population growth and urbanisation rates are outstripping the demographic development of the hinterland, driven by rapid economic growth and coastward migration [4, 5]. In China and Bangladesh, for example, the population in the low-elevation coastal zone (LECZ) grew at around twice the rate of the national growth between 1990 and 2000 [5]; the LECZ is commonly defined as the contiguous and hydrologically connected zone of land along the coast and below 10 m of elevation [5, 6]. In China, the growth of coastal urban areas is high at more than three times the national rate, which has been associated with the ongoing economic development and specific policies that drive coastward migration [5]

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