Study finds more than half of the world's coastal settlements retreating inland
Researchers say retreat is occurring where people can move; poorer regions remain at risk, highlighting adaptation gaps
A new study finds that more than half of the world's coastal settlements are retreating inland to avoid rising sea levels, as communities confront stronger storms, coastal erosion and higher seas. Lead author Xiaoming Wang of Monash University in Australia said the shift is happening but uneven, noting that moving inland is more feasible for some than for others: "For the first time, we've mapped how human settlements are relocating from coasts around the world. It's clear that moving inland is happening – but only where people have the means to do so."
The international team, based in China, Indonesia and Denmark, analyzed nearly three decades of satellite nighttime light data from 1992 to 2019 across 1,071 coastal regions in 155 countries. The light data served as a fingerprint of settlement patterns—indicating where human habitation remains active or shifts away from the coast, even if city boundaries stay the same. The researchers found that 56 percent of regions relocated inland, 28 percent stayed put, and 16 percent moved closer to the coast.
Regional patterns show the steepest inland shifts occurred in South America (up to 17.7 percent) and Asia (17.4 percent), followed by Europe (14.8 percent), Oceania (13.8 percent), Africa (12.4 percent) and North America (8.8 percent). The study notes that Oceania has some of the closest settlements to the coast overall, reflecting its reliance on coastal economies; in Australia, many major cities sit near water rather than inland.
The research also found clear socioeconomic divides. Poorer groups are more likely to move closer to the coast or remain in hazard-prone areas, driven in part by informal settlements clustered near shoreline jobs such as fishing and port activities. By contrast, higher-income groups are more capable of staying put in coastal zones or relocating inland, which underscores concerns that adaptation gaps could widen if protections and relocation options are not equitably available.
"Relocating away from the coast must be part of a long-term climate strategy," Wang said. "The rationale for policy and planning to relocate people requires meticulous consideration of both economic and social implications across individuals, communities and regions. Alongside climate change mitigation, it needs to be combined with efforts to reduce coastal hazard exposure and vulnerability, improve informal settlements, balance coastal risks with livelihoods and maintain sustainable lifestyles in the long-term. Without this, coastal adaptation gaps will continue to be widened and leave the world's poorest behind."
The study arrives as scientists emphasize that global warming is driving sea-level rise through two intertwined processes: the addition of meltwater from glaciers and ice sheets and the thermal expansion of seawater as it warms. Warmer air can hold more moisture, increasing rainfall and flood risk in coastal zones. Researchers caution that the threats facing coastal communities are likely to intensify as hazards rise and protective infrastructure faces new strains.
Global sea levels could rise dramatically if West Antarctica’s Thwaites Glacier destabilizes, a scenario some scientists warn could push sea levels higher by as much as 3 meters (about 10 feet). Such a rise would threaten coastal cities worldwide, from Shanghai and London to low-lying areas of Florida and Bangladesh, and could imperil entire nations such as the Maldives. In the United States, prior assessments have projected substantial increases in tidal flooding along East and Gulf coasts in coming decades; in the United Kingdom, some projections suggest that a two-meter rise by 2040 could put large parts of Kent, as well as areas around Portsmouth, Cambridge and Peterborough, at risk of submergence.
The Nature Climate Change study emphasizes that retreat from coastlines is a real human response to coastal climate hazards and that adaptation policy must consider both the social and economic dimensions of relocation. As coastal risks intensify, officials and communities face difficult tradeoffs between protecting existing coastal livelihoods and helping residents move to safer inland locations while maintaining sustainable, resilient communities.