By 2100, rising sea levels threaten to inundate the habitats of approximately 15,000 land vertebrate species, with birds and mammals facing the highest risk of partial habitat loss.
New research published in Science indicates that coastal inundation will disproportionately affect island-dwelling animals and vulnerable populations already classified as threatened.
As of Monday, November 11, 2026, the global rate of sea-level rise has surpassed 4 millimeters annually—more than double the rate observed between 1993 and 2002. Scientists warn this trajectory could accelerate to 10 millimeters per year in the near future. While climate discussions often focus on temperature-driven drought or heat, this study highlights the physical encroachment of water onto land as a primary driver of biodiversity loss.
The research team, led by Zhong-Wen Jiang, analyzed 34,120 land vertebrate species—covering 90% of known species—to map potential habitat exposure under five distinct emissions scenarios. The findings suggest that between 14,300 and 15,300 species will experience partial habitat flooding by the end of the century.
The impact is not distributed evenly; birds and mammals are projected to see the highest proportion of their ranges affected, while reptiles and amphibians, though affected in smaller numbers, face the most severe proportional habitat loss.
The study identifies specific geographic regions where the intersection of high biodiversity and rising tides creates acute conservation challenges. Southeast Asia stands out as a critical hotspot, housing a high density of threatened species within low-lying coastal zones. Similarly, the Amazon delta is projected to lose more than 1,000 square kilometers of inland habitat to inundation by 2050.
The danger is compounded for island-dwelling endemics, which lack the ability to retreat inland as sea levels rise. Because these species occupy narrow geographic ranges, even minor shifts in coastal boundaries can trigger significant increases in extinction risk. The researchers note that the ratio of coastline to interior land mass makes islands disproportionately susceptible to these environmental pressures.
| Species Group | Affected Species Range | Key Vulnerability |
|---|---|---|
| Birds | 57%–63% | Breeding & migratory site loss |
| Mammals | 47%–52% | Coastal range restriction |
| Reptiles | 28%–36% | High proportional habitat loss |
| Amphibians | 20%–24% | Limited mobility/retreat options |
The data suggests that species already considered threatened face a disproportionate burden, losing on average five times the share of habitat compared to those currently listed as “least concern.” Specific animals, including the worm lizard (Amphisbaena littoralis), the Catalina chuckwalla (Sauromalus klauberi), and the Restinga toadlet (Melanophryniscus setiba), are projected to lose nearly half of their habitable range under high-emissions scenarios.
The study found that more than 96% of the identified high-priority refuges—areas expected to remain above water through 2100—currently lie outside existing protected areas. This discrepancy suggests that current global conservation strategies may be misaligned with the long-term geographic realities of a changing coastline.
The study also warns that traditional coastal defenses, such as sea walls or dikes, may inadvertently create "coastal squeeze," where wildlife is trapped between human-made barriers and rising waters, further limiting their ability to adapt.
Conservation efforts often compete with urban expansion and industrial development in coastal regions. “Species-level habitat data, including elevational ranges and habitat preferences, can refine broad geographic distributions into more precise estimates of habitat exposure, enabling conservation actions tailored to species-specific risks,” the authors said in their findings.
Earlier coverage: Rising Sea Levels Threaten Habitats of Over 40% of Land Vertebrates
