Coastal zones concentrate people and economic activity: over 40% of the global population lives within 100 kilometres of the coast. A new global study using satellite night-time light observations finds many communities have moved inland over the past 30 years as climate hazards intensified.
The research, published in Nature Climate Change, was led by researchers at Sichuan University and included remote sensing experts from the University of Copenhagen, Alexander Prishchepov and Shengping Ding, IGN. The team combined night-time lights with global socioeconomic datasets to map settlement movements in 1,071 coastal regions across 155 countries.
- 56% of coastal regions retreated from the coast between 1992 and 2019.
- 16% moved closer to the coast, including the Copenhagen area in Denmark.
- 28% remained stable.
- Africa (67%) and Oceania (59%) showed the highest shares of retreat.
The study finds retreat is driven more by social and infrastructural vulnerability than by the historical frequency of hazards. Nearly half of low-income regions cannot retreat because they rely on coastal land for livelihoods and lack alternatives, leaving millions exposed to flooding and erosion. Retreat is most common in middle-income countries, which often have enough institutional capacity and funds to relocate but not the wealth to prioritise heavy protection. Mixed-effects modelling showed a 1% improvement in adaptive capacity corresponded to a 4.2% reduction in retreat speed, and a 1% increase in structural protection corresponded to a 6.4% reduction. The authors caution that night-time light data can miss settlements with limited electrification and call for further study to inform proactive coastal planning.
Difficult words
- socioeconomic — relating to social and economic conditions
- retreat — movement of people or settlements inlandretreated
- vulnerability — weakness that increases risk of harm
- adaptive capacity — ability of communities or systems to adapt
- structural protection — physical measures built to reduce hazards
- electrification — provision of electrical power to homes
- remote sensing — collecting data about Earth from a distance
- satellite — a man-made object orbiting a planet
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What challenges do low-income coastal communities face that limit their ability to retreat? Give two examples from the article.
- How might governments balance relocation and structural protection when planning for rising coastal hazards?
- Do you think satellite night-time light observations are enough to guide coastal policy? Why or why not, and what other data would help?
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