A research team from Sun Yat-sen University in Guangzhou, working with researchers in China and abroad, has systematically assessed the potential impact of future sea-level rise on 34,120 species of terrestrial vertebrates worldwide and identified potential refugia with high conservation value.

The findings, led by Ma Liang and Chen Yaping from the university's School of Ecology at the Shenzhen campus, were published in the journal Science on Friday under the title "Safeguarding Global Terrestrial Vertebrate Species From Future Sea-Level Rise".

According to the study, between 14,325 and 15,324 of the terrestrial vertebrate species examined could see parts of their habitats inundated by the end of the century, representing up to 45 percent of the species surveyed.

However, habitat inundation does not necessarily translate into extensive habitat loss or an increased risk of extinction, as vulnerability varies considerably among species. More than 96 percent of the potential refugia identified by the researchers lie outside existing protected areas, highlighting gaps in the current conservation network and providing scientific evidence to inform future biodiversity conservation strategies.

Ma, an associate professor at the school and co-corresponding author of the paper, said sea-level rise poses a major and unavoidable challenge to global biodiversity conservation.

Southeast Asia faces substantial pressure from biodiversity loss in areas projected to be inundated, although the study also identified numerous potential refugia for species, most of which are outside the existing protected area network.

The mouth of the Amazon River and adjacent low-lying areas were also identified as high-risk zones. These areas support exceptionally high terrestrial vertebrate diversity, while seawater intrusion threatens the habitats of riparian forests and coastal wetland ecotones.

The consequences of rising sea levels are already evident in several regions. In 2019, Australia formally declared the extinction of the Bramble Cay Melomys, a small mammal that once inhabited a low-lying coral reef island off northern Australia. Habitat loss associated with sea-level rise has been identified as a key factor in its extinction.

On the Dutch Wadden Islands, increasingly frequent flooding of oystercatcher breeding sites threatens local populations. Along North America's Atlantic coast, saltmarsh sparrow nests also face growing risks from inundation.

"While these examples crop up in regional research, globally we lack systematic knowledge about the number of threatened species, the location of high risks, and optimal arrangements for conservation actions," said Jiang Zhongwen, a co-first author of the study and a postdoctoral researcher at the School of Ecology.

To address this knowledge gap, the team developed a framework that combines sea-level rise projections with detailed assessments of species' habitats. Forecasts of future sea levels must account for different climate scenarios, regional variations in sea-level rise and land subsidence. Meanwhile, assessing habitat exposure for tens of thousands of terrestrial vertebrate species requires detailed information on their elevation limits and habitat preferences, rather than relying solely on broad species distribution ranges.

Jiang said the team spent more than two years conducting the research and brought together international experts from multiple disciplines to refine its methodology, drawing on detailed habitat analysis, systematic conservation planning, sea-level rise assessment and other ecological fields.

Xiao Hengbin, another co-first author and a postdoctoral researcher at the school, said the team used multiple climate scenarios to model species' exposure to sea-level rise in 2050 and 2100.

"By 2100, around 45 percent of surveyed species globally could suffer habitat inundation, but still, merely 5.9 percent of these vulnerable species are marked with climate change threats on the IUCN Red List," Xiao said.

"This suggests that biodiversity risks caused by sea-level rise are not fully integrated into existing species conservation assessments," he added.

The study found marked differences in vulnerability among animal groups. Birds and mammals had a higher proportion of species exposed to sea-level rise, while amphibians and reptiles faced substantially greater habitat loss among the affected species.

On average, reptiles experienced twice the proportion of habitat inundation recorded for birds and mammals. Under high-emission scenarios, the number of species facing inundation of more than 10 percent of their habitats is projected to rise from 18 in 2050 to 109 by 2100, with reptiles and threatened species accounting for a large share of the total.

Chen, the co-corresponding author, said the research is important not only for identifying ecological risks associated with sea-level rise but also for providing a scientific basis for proactive conservation measures. She noted that many developing countries with potentially important refugia face funding shortages and limited technical capacity. Addressing cross-border ecological threats will therefore require closer international cooperation, including financial assistance, technology exchanges and support for conservation capacity building.

According to the World Meteorological Organization, the global mean sea level rose at an average rate of about 4.7 millimeters per year from 2015 to 2024, more than twice the rate recorded from 1993 to 2002. Under high-emission scenarios, the rate could exceed 10 mm per year by 2100.

Contact the writers at zhengcaixiong@chinadaily.com.cn