Did climate change cause a toad to go extinct? A Flagstaff author explores the mystery

• The golden toad, native to Costa Rica, has not been officially seen in over 36 years. A 2022 IPCC report named climate change a key driver in the golden toad’s extinction.
• Researchers debated whether a fungal disease or climate change caused the species’ disappearance.
• Author Trevor Ritland went on a quest to find the toad’s killer and still hopes he might find evidence that could recover.

This is part of a monthly series answering readers’ climate-related questions and highlighting Arizona’s unsung climate leaders. The stories aim to help connect and inspire Arizonans who care about protecting a livable climate and may be struggling to find hope in that effort. You can ask a question or nominate an unsung Arizona climate leader by filling out this form at https://forms.gle/QCCxBPSHGy1bUJQ99 or by emailing climate reporter Joan Meiners at joan.meiners@arizonarepublic.com.

Over coffee and eggs in Flagstaff, Trevor Ritland’s face became animated as he talked about the golden toad.

It had been one week since his book about the species published and just over 36 years since the last time anyone officially saw one.

We discussed how the strikingly orange amphibian, native to Costa Rica and captivating to anyone who was lucky enough to see one, captured his interest so wholly that he spent much of his 20s going back and forth between Arizona’s high desert and the Central American cloud forest trying to find one.

Ritland, like most people, has not laid eyes on one of these golden treasures in the flesh. Or, at least, he hasn’t told anyone that he has. He’s not sure he would, as he hopes the toad makes a quiet recovery someday — one that could be threatened by a surge of tourism to see the famous species if it ever did resurface. But he did find a lifelong passion, plenty of community and the subject for a book along the way.

”The Golden Toad: An Ecological Mystery and the Search for a Lost Species,” which Ritland wrote with his brother, Kyle Ritland, was published by Simon and Schuster Press on June 17. Ritland, who studied filmmaking and science communication at Northern Arizona University, has also produced a documentary about the species and ongoing searches for it that is available in both English and Spanish.

The book is framed as a mystery: a quest to find the killer of this majestic species that lived a vibrant but largely unknown life in highly specific habitats limited to the Monteverde region of Costa Rica. The animal spent much of its fossorial lifecycle buried under mud. When the right rainfall and temperature conditions hit, it would emerge, mate and lay eggs in tiny pools of water held by tree root hollows. The neon spectacle was only ever witnessed by a handful of Costa Rican locals and scientists.

Then suddenly one year, the species just vanished. For decades researchers argued about why.

I sat down with Ritland in June to discuss what role climate change played in the story of this species and his quest. Then I got sidetracked by preparations for my own quest to document climate impacts in Arizona while riding my bike on trails across the state, and the conversation got put on hold. The toad, after all, wasn’t going anywhere.

Then, the question: “Has any species actually ever gone extinct due to climate change?” emerged from a reader like a creature from the mud, and it seemed like a perfect opportunity to dig up the discussion about golden toads as part of The Arizona Republic’s monthly series answering reader’s climate questions and profiling Arizona climate leaders.

On its surface, this question has a formal answer. In 2022, a report published as part of the Intergovernmental Panel on Climate Change’s semi-regular updates on global climate risks and impacts named climate change as a “key driver” in the extinction of Incilius periglenes (previously Bufo periglenes), the golden toad of Costa Rica.

Select scientists had published this theory as early as 1999, writing in the prestigious scientific journal Nature that “Because climate affects host-parasite relationships and amphibians in various ways, it may have set the stage for mortality events, including those ascribed to chytrid fungus outbreaks.” And the species has been listed as extinct by the IUCN Red List since 2004.

But 2022 was the first time climate change was officially charged with killing off a particular terrestrial species. The methodologies of science are often painfully slow, even when answers have long been clear to those watching closely.

The determination enshrined the golden toad in a sad hall of fame. It also seemed to stamp a final decision on a debate that had been dividing amphibian researchers vying for the same pots of funding to address the threats of disease versus climate change for decades.

Chytrid fungus, the disease in question, is now recognized to have “decimated” the biodiversity of amphibians, contributing to the extinction of at least 90 species as it spread across the world in the mid- to late-1900s. But this pathogen, Batrachochytrium dendrobatidis, wasn’t officially described until 1988, the same year of the last golden toad sighting. By then, climate change had entered the chat.

Ritland — who does not claim to have scientific expertise himself but has delved deeply into this topic with the researchers who do — found himself caught in the crosshairs of this debate as he worked on his documentary and book examining what killed the golden toad. Looking back, he described the perspective that chytrid fungus was the sole cause of the toad’s extinction as “almost like a tunnel view.” A changing climate in Monteverde, which has been documented locally dating back to weather-hobbyist Quaker settlers who arrived in the area after World War II, clearly played a role. But Ritland can sympathize with how that conclusion may be confusing.

“This is where we get into the interesting kind of paradox of understanding the climate role,” Ritland said at breakfast. “So chytrid actually thrives best in colder, wetter conditions. So you would think, ‘oh, global warming will help the toad.’ But climate change doesn’t just mean warming, it means more extremes. And in Monteverde, they’re actually seeing colder, wetter seasons, which is one of the theories of why chytrid was so effective there.”

As climate change advances and researchers get a better grasp on how it interacts with threats like the susceptibility of sensitive species to disease, parasites and altered habitats, the tally of plants and animals lost as a result will continue to rise. But while Ritland would love to see the golden toad come back, he finds optimism in the local response to its disappearance.

Costa Rica has been a leader in international climate policy. It adopted a National Decarbonization Plan in 2019. And for a small nation, it had a strong showing at the 2025 United Nations Climate Change meeting, to which the United States did not send a single delegate.

In Monteverde specifically, the local community has responded to vanishing species and changing conditions, including recent mudslides that have wiped out family homes that stood for generations, by setting aside large swaths of land for conservation and shifting from an economy based on grazing and farming to one thriving on ecotourism.

“What I learned while writing this book is that there are places and situations where, literally, individual people can still make a difference,” Ritland told me, crediting his toad-searching collaborator Eladio Cruz with selling his land to the Children’s Eternal Rainforest preserve and inspiring other ranchers and farmers to do the same. “When there’s a lot of reasons to be pessimistic, I think that’s really encouraging.”

“The world we live in here in Arizona is very different from rural Costa Rica,” he continued. “But I think there are always those opportunities if you understand a place and the way it is being impacted where individual action can make a big impact. So in that sense, I think the extinction of the golden toad is a hopeful story, because it was a catalyst that sent not only Monteverde, but Costa Rica and in some sense the broader world, down a better path.”

Joan Meiners is the climate news and storytelling reporter at The Arizona Republic and azcentral.com. Her award-winning work has also appeared in Discover Magazine, National Geographic, ProPublica and the Washington Post Magazine. Before becoming a journalist, she completed a doctorate in ecology. Follow Joan on Twitter at @beecycles, on BlueSky at @joan.meiners.bksy.social or email her at joan.meiners@arizonarepublic.com.