Up in the misty mountains, teems a kaleidoscope of life: trees drip with epiphytes, hummingbirds sip from bright blossoms, and rare creatures occupy every nook in the cloud forests, which scientists have likened to terrestrial coral reefs. But a new study warns that climate change could strip away the conditions that make cloud forests possible, and in the worst case, erase nearly all of them within 50 years.
The research, published in the Journal for Nature Conservation, used machine learning and modeling to project how cloud forest distribution in South America could shift under two different climate scenarios by 2070.
The study reports that under a high-emissions pathway, up to 91% of cloud forest area could be lost. Even under the most optimistic scenario, researchers calculate a 12% reduction, roughly 21,000 square kilometers (8,100 square miles), an area the size of El Salvador.
Cloud forests occupy a narrow band of land, typically between 1,000 and 3,000 meters (about 3,300-10,000 feet) above sea level, and are defined by persistent fog, cool temperatures and high humidity. That humidity shapes everything, from the mosses and orchids draped across surfaces, to the birds and amphibians found nowhere else on Earth.
The study notes these ecosystems harbor some 1,946 restricted-range species, representing roughly 8% of the world’s mammals, birds, amphibians and tree ferns. Among the species endemic to South American cloud forests are the flamboyant Andean cock-of-the-rock (Rupicola peruvianus), whose brilliant orange-plumed males perform elaborate courtship dances on the forest floor; the critically endangered yellow-tailed woolly monkey (Lagothrix flavicauda), Peru’s largest endemic primate; and countless glass frogs — delicate, translucent amphibians whose eggs can be seen developing through their own skin.
As temperatures rise, the base of clouds climbs higher up the mountain slopes, effectively shrinking the zone where cloud forests can exist. Species are pushed upward into increasingly fragmented habitat. For those species that live only near the summits, there is nowhere left to go.
But the stakes go beyond biodiversity. Because cloud forests capture fog on their leaves and branches and release it steadily into surrounding watersheds, communities downstream depend on them for reliable drinking water, particularly during dry seasons when other sources run low.
The researchers estimated that about 19.5 million people live within 5 kilometers (3 miles) of rivers whose flow is influenced by upstream cloud forests. Study lead author Patrícia Vieira Pompeu, a professor at the State University of Mato Grosso do Sul in Brazil, warned that under the high-emissions scenario, that supply would be compromised for an estimated 16 million people, or 83% of current beneficiaries.
“Cloud forests play an important role in regulating water in the headwaters of many Amazonian rivers, especially those originating in the Andes and other elevated regions of northern Amazonia,” Pompeu told Mongabay. “Their loss could reduce dry-season water availability and increase hydrological variability in Andean–Amazonian tributaries, potentially affecting downstream ecosystems and human populations.”
The study also found that only about one-third of South America’s cloud forests currently fall within protected areas. But that protection offers no guarantee of survival if the climate itself becomes unsuitable. Under the high-emissions scenario, the remaining protected patches would shrink dramatically in size, potentially becoming too small and isolated to support viable populations of many species.
“Cloud forests are already known to face many threats from human land-use change,” Walter Jetz, a biodiversity scientist at Yale University in the U.S., who wasn’t involved in the study, told Mongabay. “Montane cloud forests exist in a slim and globally rare climate space marked by cold and foggy conditions. There is no doubt that changing climate, combined with their narrow distribution and encroachment, makes montane cloud forests some of the most vulnerable highly biodiverse ecosystems on the planet.”
The study’s authors argue that two strategies are especially critical for the survival of cloud forests: stronger implementation of payments for ecosystem services, which provide financial incentives for landholders to conserve or restore forests upstream of populated watersheds; and better management of existing protected areas. Identifying which cloud forest patches are likely to remain climatically suitable even under future scenarios, they argue, should guide where those resources are focused.
But Pompeu said the most fundamental solution remains the same as for every climate-driven ecological crisis. “The key message is that we need to care about CO2 emissions,” she said. “We need to stop, or we will have problems with everything.”
Banner image of Andean cock-of-the-rocks (Rupicola peruvianus) in Ecuador. Photo by Rhett A. Butler for Mongabay.
Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.
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Pompeu, P. V., Mulligan, M., Bruijnzeel, L. A., Pires-Oliveira, J. C., Ponette-González, A. G., Brauman, K. A., … Da Rocha, H. R. (2025). Most South American cloud forests are likely to disappear under high-end climate change. Journal for Nature Conservation, 90, 127192. doi:10.1016/j.jnc.2025.127192
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