Climate change plays a critical role in the declining populations of amphibians due to habitat loss, diseases and constant environmental changes. Amphibians are very sensitive to these environmental changes which may lead to problems in survival or breeding.
A paper published in scientific journal Nature analyzing more than 20 years of data from around the world has found that climate change is emerging as one of the biggest threats to frogs, salamanders, and caecilians. Previously, disease and habitat loss were responsible for 91% of species deteriorations. Since 2004, the effects of climate change has become a growing concern leading to 39% of status deteriorations.
The IUCN Red List Index(RLI) documents the extinction risk of species over time providing crucial information to scientists for conservation prioritization and planning. The 2004 Global Amphibian Assessment (GAA1) revealed Amphibians as the most threatened vertebrates mainly due to over-exploitation, habitat loss and degradation. This research paper also identified chytridiomycosis, caused by Batrachochytrium dendrobatidis, is most likely a major factor behind many enigmatic declines.
By June 2022, the second Global Amphibian Assessment (GAA2) reassessed the status of the GAA1 species and added 2,286 additional species, increasing the total number of amphibians to 8,011. Improved data and projections on the species suggests that this number is expected to rise in response to climate change as these species are particularly sensitive to changes around their environment.
Global Amphibian Decline: Key Insights
Amphibians face escalating threats worldwide, with 40.7% of species globally threatened and increasing rates of extinction. This summary highlights the most affected regions, primary threats, and extinction trends to guide urgent conservation actions.
Key Statistics
| Category | 1980 | 2004 | 2022 |
|---|---|---|---|
| Globally Threatened Species (%) | 37.9% (2,681) | 39.4% (2,788) | 40.7% (2,873) |
| Documented Extinctions | 23 | 33 | 37 |
| Critically Endangered (Possibly Extinct) | 24 | 162 | 185 |
Most Affected Regions
- Caribbean Islands
- Mesoamerica
- Tropical Andes
- Western Cameroon and Eastern Nigeria
- Madagascar
- Western Ghats and Sri Lanka
- Southern Brazil (Atlantic Forest)
- Eastern Arc Mountains (Tanzania)
- Southern Annamite Mountains (Vietnam)
Top Documented Threats faced by Amphibians
| Threat Type | % Species Impacted |
|---|---|
| Agriculture | 77% |
| Timber/Plant Harvesting | 53% |
| Infrastructure Development | 40% |
| Climate Change Effects | 29% |
| Disease | 29% |
These key findings emphasize the need for planned conservation efforts addressing habitat loss, disease and climate change.
RLI Indicator
The RLI is an indicator calculated from Red List categories to measure trends in extinction risk over time. It accounts only for genuine status changes and excluding non-genuine shifts through backcasting. RLI trends for amphibians were analyzed for 1980, 2004, and 2022, showing a consistent decline, though the rate of decline slightly slowed between 2004 and 2022.
Regional RLI Trends
Neotropics:
- Lowest RLI value, with the sharpest decline.
- Decline linked to chytridiomycosis outbreaks (1970s–2000s).
Australasia:
- Highest RLI due to fewer threats on chytridiomycosis-free New Guinea.
Palaearctic:
- Habitat loss dominates, with emerging fungal pathogen Batrachochytrium salamandrivorans becoming a concern.
Nearctic:
- Climate change is the leading threat, followed by habitat loss.
Afrotropics:
- Decline driven initially by habitat loss, shifting toward disease as a dominant threat.
Indomalayan:
- Slight improvement due to protected area management.
Breeding Strategies and Extinction Risk
- Direct Developers: Higher extinction risk, decline accelerated post-2004.
- Larval Developers: Decline slowed post-2004, reflecting earlier impact from chytridiomycosis outbreaks.
- Live Bearers: Slightly accelerated decline post-2004.
This result is probably due to larval developers having been especially impacted by B. dendrobatidis before 2004 when chytridiomycosis outbreaks were at their peak (particularly in high-elevation streams). The causes of differing extinction risks between breeding strategies merit further study.
Phylogenetic Patterns (Study of Evolutionary history of Organism)
Phylogenetic Patterns among amphibians reveal varying extinction risks. Caudata (salamanders and newts) are the most threatened, with an accelerated decline observed post-2004. Anura (frogs) experienced a sharper decline before 2004, attributed to the peak of chytridiomycosis outbreaks, with a slower decline thereafter. Gymnophiona (caecilians) show a slight decline; however, limited data—44% classified as Data Deficient and 17% as threatened—hinders a comprehensive assessment. These variations highlight the need for further research and conservation strategies for each group.
Conservationists and biologists can use this information to help conclude a policy for global conservation action plan and prioritize action at large scale to reverse the impacts of Climate change on amphibians.