Climate change is emerging as one of the biggest threats to frogs and other amphibians, according to a major study published Wednesday in the journal Nature. Between 2004 and 2022, rising temperatures became the primary reason more than 100 amphibian species are slipping toward extinction.

“It’s a gut punch and an awakening,” said JJ Apodaca, executive director of the nonprofit Amphibian and Reptile Conservancy. He was not involved in the study.

The spread of disease among frogs and the destruction of swamps and other habitats have long been recognized as reasons many amphibians are declining.

But this new study establishes climate change as a major risk for amphibians around the world, too. The soft-skinned animals lack the scales, fur and feathers of other animals to help regulate their temperature and moisture levels in this hotter and more drought-stricken world.

“There is a growing proportion of species being pushed to the brink of extinction by disease and the effects of climate change,” said Jennifer Luedtke, an amphibian group coordinator with the International Union for Conservation of Nature and one of the lead authors of the study from more than 100 researchers.

“So habitat protection alone just won’t be sufficient as a risk-reduction measure.”

What we lose when amphibians vanish

Over 2 in 5 amphibian species are at risk of extinction, according to the report, making them the most threatened group of vertebrates. By comparison, roughly a fourth of mammals and an eighth of birds are at risk of vanishing for good.

Frogs and other amphibians are “overlooked compared to more well-known groups like birds and mammals,” said Kelsey Neam, another study co-author. But losing amphibians would be devastating because they often act a crucial link in the food web of ecosystems, gobbling up insects and, in turn, being eaten by larger predators.

“Without those amphibians to fulfill that niche, we will see this collapse of the food web,” said Neam, who like Luedtke works for an Austin-based environmental group called Re:wild.

Among amphibians declining because of climate change are the coquí frogs native to Puerto Rico, which are retreating up the island’s mountains as temperatures go up.

Named for their two-note “co-qui” call, the island’s iconic frogs are decreasing in body size and croaking at a higher pitch as temperatures increase. Eventually, the island may get so hot that the frogs run out of room up the mountains. Already, at least three of Puerto Rico’s coquís are presumed extinct.

Another potential victim of climate change is the golden toad of Costa Rica. Hotter and dryer conditions in its rainforest home may have made the colorful toad more vulnerable to a deadly fungal disease that attacks amphibians’ skin. The last one was seen in 1989.

“It’s a beautiful, beautiful toad,” said Patricia Burrowes, a retired herpetologist at the University of Puerto Rico. “I’m old enough to have seen these frogs disappear.”

That fungal infection, called chytridiomycosis, has ripped through amphibian populations from Latin America to Africa to Australia, driving hundreds of amphibians toward oblivion. By one measure, it is causing the worst loss of biodiversity of any wildlife disease in history.

‘Not all bad news’

Yet for all the threats frogs face, the study concluded the salamander is the most endangered type of amphibian. About 3 in 5 of the slender amphibians are at risk of vanishing, according to the study in Nature.

Many salamander species live in only one place, making them particularly susceptible to climate change and habitat fragmentation. The Hickory Nut Gorge green salamander, for instance, lives exclusively in a 14-mile-long canyon in North Carolina’s Blue Ridge Mountains.

“This isn’t a problem that exists in the tropics and doesn’t affect people here in the United States,” said Apodaca, who helped discover the salamander species.

The first major assessment of declines in amphibians came out in 2004, and this study uses the data from a recently completed second assessment. “Things have gotten even worse” since then, Apodaca said.

There are still signs of hope. Habitat protection and other conservation measures have helped in the recovery of more than five dozen amphibians from Costa Rica to Malaysia.

“It’s not all bad news,” Luedtke said. “But we really must build on this momentum and significantly scale up investment in amphibian conservation.”