Up to 80 percent of South America's cloud forests could vanish by the end of this century. That is the stark finding of a new study published in the journal Nature Climate Change, which looked at how rising global temperatures and shifting cloud cover will affect these misty, high altitude ecosystems.
The forests that drink the clouds
Cloud forests are rare and fragile. They form on mountain slopes where persistent fog and low clouds provide a steady source of moisture. In South America, they stretch across the Andes from Venezuela to northern Argentina, with the largest remaining patches in Colombia, Ecuador, Peru, and Bolivia. These forests are home to an extraordinary number of species found nowhere else on Earth, including the dazzling Andean cock of the rock and hundreds of types of orchids, frogs, and hummingbirds.
Local communities have long depended on these forests for clean water. The trees and moss act like sponges, capturing fog and releasing it slowly into streams and rivers that supply cities and farms below. In Ecuador, for example, cloud forests provide drinking water for Quito and other major urban centers.
What the study found
Researchers used climate models to simulate how cloud cover patterns might change under different warming scenarios. They found that even under moderate emissions, the cloud base is likely to rise. As the atmosphere warms, the altitude at which clouds form moves higher up the mountains. That means the forests that rely on those clouds will be left dry.
Under a high emissions scenario, the study warns that 80 percent of South America's cloud forest habitat could become unsuitable by 2100. Some low elevation cloud forests could disappear entirely. Even in protected areas, the threat is severe because the problem is not deforestation but a change in the climate itself.
The study was led by scientists from the University of Cambridge and the University of Exeter in the United Kingdom, in collaboration with researchers in South America. They analyzed data from more than 200 cloud forest sites across the continent.
Why this matters for people and wildlife
For the people living near these forests, the loss would mean less water. Cloud forests capture up to 60 percent of the moisture that falls as rain or fog in some regions. Without them, water supplies for agriculture and drinking could become unreliable.
For wildlife, the outlook is grim. Many species in cloud forests have very narrow temperature and humidity ranges. They cannot simply move up the mountain because the mountain top is finite. Once the cloud line rises above the highest peaks, there is nowhere left to go.
The study does not offer solutions. It presents a projection based on current emissions trends. But it makes clear that the fate of these forests is tied directly to global climate policy. The clouds that sustain them are not bound by national borders or park boundaries.
