99% habitat loss: The dire future of amphibians in the Pantanal

A newly published study paints a grim picture for amphibians in the Upper Paraguay River Basin, which includes the vast Pantanal wetlands and surrounding areas. The researchers predict that the region may lose almost all suitable habitats for toads, frogs, and tree frogs by 2100. 

The findings emerge from a collaboration between researchers from Brazil and Switzerland, who combined species distribution data with climate modeling.

Most amphibians will lose their habitats

The experts cross-referenced locations of amphibian species with two greenhouse gas emissions scenarios (one optimistic, one pessimistic). The team concluded that more than 80% of amphibian species in the Upper Paraguay River Basin would lose suitable habitats.

In the optimistic scenario, 99.87% of the basin would experience local extinctions, and in the pessimistic one, this figure rises to 99.99% of the region, according to lead author Matheus Oliveira Neves of the Federal University of Mato Grosso (UFMT). 

With these numbers, there is scant room left for doubt: amphibian biodiversity in the Pantanal and nearby zones appears to be on a steep and accelerating decline.

Current protection falls short

The researchers also found that existing protected areas – integral conservation units – cover only 5.85% of the territory, and within those reserves, less than 5% of amphibians’ geographical ranges are effectively safeguarded. 

“Fully protected conservation units are currently doing very little to protect amphibian species in the Pantanal,” said Brazilian researcher Mario Ribeiro Moura, who coordinated the project while at the Institute of Biology of the State University of Campinas (IB-UNICAMP). Moura is now a professor at the Federal University of Paraíba (UFPB).

The international community, alarmed by the accelerating loss of biodiversity, recently called for 30% of Earth’s surface to be set aside in protected areas by 2030. Moura notes that right now, this coverage stands at just 17%, including both conservation units and indigenous lands. 

He and his team argue for the creation of new protection zones and enlargement of existing ones, focusing on regions that modeling indicates will remain relatively hospitable to amphibians as climate change advances.

Two divergent climate futures

The research used future climate projections from the Intergovernmental Panel on Climate Change (IPCC). In one model, an optimistic scenario keeps emissions at current levels, leading to an estimated 2 °C increase by 2100. 

In a more pessimistic model, emissions continue to rise, potentially pushing the temperature up by 4 °C by century’s end. 

For the Upper Paraguay River Basin – including parts of Paraguay and Bolivia – the difference between these scenarios translates into a near-total collapse (99.87% or 99.99%, respectively) of viable amphibian habitats.

The team relied on more than 4,000 records for 74 amphibian species native to the basin. These species encompass a wide range of frogs, toads, and tree frogs that are highly dependent on moisture and aquatic environments – features that climate change, habitat conversion, and other human impacts are making increasingly rare or degraded.

Few viable refuges in the future

Even in the best-case scenario, the study suggests that the most likely refuges for amphibians occur near Cuiabá in northern Mato Grosso, on the edge of the Cerrado savannah, and in the southeast near Campo Grande in Mato Grosso do Sul state. 

Some southwestern areas near the Paraguayan Chaco may remain viable as well. However, these spots represent only a fraction of the Upper Paraguay River Basin.

The researchers also found that among the protected areas currently established, hardly any harbor an amphibian diversity above the baseline. 

While a small number of protected zones may actually see unexpected gains in species, the authors caution that the net picture is one of overall loss. 

“In summary, only 13.7% of the current protected areas in the Upper Paraguay River Basin have the potential to host more or lose fewer species in at least one future scenario. Most of these areas are indigenous lands,” noted Moura.

Protecting habitats for amphibians

Moura and colleagues advocate for a combination of new conservation areas, expanded existing reserves, and changes in land use practices that limit the destruction of aquatic ecosystems. They further stress the magnitude of the climate challenge. 

“While the Paris Agreement aimed to limit the global temperature increase to 1.5 °C by the end of the century, we already reached that level in 2024,” Moura said. 

In his opinion, the global economic model remains deeply entwined with fossil fuel consumption, and without “radical” mitigation steps, both biodiversity and human society face profound risks.

For the amphibians of the Upper Paraguay River Basin – creatures that rely on stable, humid environments – time is running out. 

The results indicate that if greenhouse gas emissions continue unabated, nearly all of the watery niches they need could vanish, drastically shrinking populations and possibly setting the stage for mass regional extinctions. 

On the other hand, through determined conservation policy and aggressive climate action, it may still be possible to give these species a chance to survive and thrive well beyond this century.

The study is published in the Journal of Applied Ecology.

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