A mass extinction of species, particularly of terrestrial vertebrates, could be triggered before the end of the century.
This is warned by a recent study published in Global Change Biology, which analyzed 29,657 species worldwide to reach this conclusion.
Facing 2100, the lethal combination of extreme heat waves and land use change threatens to bring thousands of species to the brink of extinction, it reveals.
The work identified that the interaction between climate crisis and landscape transformation exposes animals to unprecedented risk.
Up to 7,895 species at risk of extinction by 2100
The results of the University of Oxford study projected that by 2100, up to 7895 species could face completely unsuitable conditions for them, with a risk of extinction.
The analysis considered amphibians, birds, mammals, and reptiles globally distributed.
Under the most optimistic scenario, aligned with the Paris Agreement, 10% of the species’ range would be exposed to unsuitable conditions.
However, in the worst-case scenario, this figure would reach 52%, the researchers warned.
The scientific team used socioeconomic and emissions scenarios to cross-reference distribution and habitat preferences data with land use projections.
The spatial resolution of 24.1 x 24.1 kilometers allowed identifying critical areas of suitability loss.
Amphibians and reptiles, the most vulnerable species to extinction
Amphibians and reptiles turned out to be the groups most affected by the combination of threats.
Even in the most favorable scenario, more than 23% and 13% of their distribution areas, respectively, would be exposed to unsuitable conditions.
Species with small ranges and those already threatened according to the IUCN face an especially high risk.
Habitat fragmentation limits their ability to disperse or adapt, while heat waves intensify stress.
An emblematic case is the African tree viper (Atheris broadleyi). Under the SSP3-RCP7.0 scenario, this species would lose 81% of its suitable area due to land use and 76% due to heat waves.
The result: 98% of its total range under unsuitable conditions, practically confirming the extinction of this species by 2100.
Critical regions: Sahel, Middle East, and Brazil
Subtropical regions appear as the main danger hotspots.
The Sahel (Sudan, Chad, Mali), Middle East (Afghanistan, Iraq, Saudi Arabia), and Brazil concentrate the highest concurrence of extreme heat waves and habitat loss.
In these places, transformation by human activities could leave numerous species without possible refuge.
The research analyzed the frequency, duration, and intensity of heat waves, as well as the conversion of natural habitats into agricultural or urban areas.
The study authors noted that the combined effects of climate change and land use are more severe than the sum of their individual impacts.
Moreover, extreme heat waves can affect even the most sheltered refuges.
Urgent actions needed to curb the crisis
The recommendations of the research team include coordinated measures to address multiple threats. Among the priority actions are:
- Strengthening and expanding protected areas, prioritizing ecological connectivity
- Designing comprehensive policies that jointly consider the climate crisis and land use change
- Implementing adaptive management in critical areas
- Identifying and protecting both the most vulnerable areas and species
The researchers acknowledged that their estimates could be conservative. The modeling did not incorporate dispersion constraints nor the actual connectivity of habitats, which could underestimate the risk of extinction.
Land use projections tend to be based on optimistic assumptions about agricultural productivity and technology.
However, they do not fully incorporate the effects of climate change on these factors.
The study provided a comprehensive view of the magnitude of the threats to terrestrial biodiversity.
The authors emphasized the urgency of coordinated and immediate responses to prevent an unprecedented extinction crisis.
