The world’s rainforests are vanishing. In this one country, they’re growing back.

For several decades now, the story of the world’s rainforests has been the same tragic one: These iconic, animal-filled ecosystems are getting cut down to make way for farms and ranches, roads and mines. And it doesn’t appear to be changing. In 2024, the most recent year of global forest data, the tropics lost a record 16.6 million acres of primary fores , largely to fires and agriculture. More than half of that recent loss was in Brazil and Bolivia. 

But one country has a very different narrative: Costa Rica.

In the late 20th century, Costa Rica — a Central American nation a little smaller than West Virginia — had one of the highest deforestation rates in the world. The country was losing more than 100,000 acres a year. And by 1985, forests covered less than 25 percent of its area, down from closer to three-quarters just a few decades earlier. 

But then, near the start of the millennium, the trend abruptly flipped. Deforestation plummeted, and trees started growing back. Now, natural forests blanket well over half of Costa Rica, making it one of the few places on Earth that has revived its lost ecosystems. 

How did Costa Rica do it? 

One reason that gets a lot of attention is that Costa Rica put a price tag on nature — on the natural “services” that forests provide, from sucking up planet-warming carbon dioxide to sustaining the local water supply. Nearly three decades ago, the country began paying private landowners for those services, if they conserve or restore forests on their property. That created a concrete, financial incentive to keep forests standing. Costa Rica was the first country in the world to implement a national “payment for ecosystem services” scheme. 

In the decades since, as Costa Rica’s forests came back, other countries followed in its footsteps, like Mexico and Vietnam, developing programs of their own that subsidized forest conservation. Together they fueled the idea, still popular in the conservation community, that you can save nature by valuing it in economic terms — terms that everyone, including capitalists, can understand. 

But there’s still an open question: Do these payment programs actually work? 

There has now been more than 20 years of research from Costa Rica on the program’s impact on forests. And a new study, published this month, looks more specifically at how the payment system affects biodiversity — the collecting of animals that live within them. These studies complicate the story of how Costa Rica became lush again. 

Costa Rica’s groundbreaking payment for ecosystem services program, briefly explained 

Part of what made Costa Rica’s ecosystem payment program so groundbreaking is that it recognized — at the highest level of government — that living forests are not only a source of timber, but are economically valuable for lots of other reasons: they reduce greenhouse gases, produce clean water, draw tourists, and are home to plants and animals that scientists use for biology research and drug development.

In simple terms, the government pays landowners who enroll in the program for every hectare (roughly 2.5 acres) of forest that they protect or replenish by planting new trees. They receive more or less money, depending on how they manage their land. By planting native trees in a degraded landscape, for example, landowners can earn more than $170 per hectare per year, on average, for the duration of the contract (16 years for planting native trees). If a property owner protects existing natural forest on their land, meanwhile, they earn between roughly $44 and $110 per hectare per year. If they let forests regrow naturally on pastureland, they earn less. 

At first, the government funded the program through a tax on fuel, such as gasoline. Now it also raises funds to pay landowners from other sources, such as a fee on water usage. The idea is that people who use services that forests provide should help pay for them. Forests help maintain rainfall by pumping water into the air through transpiration. They also help prevent pollution and sediment from entering the water supply.

The program provides what is essentially a subsidy for the lost opportunity that could come from farming or ranching on the land, said Giacomo Delgado, a doctoral researcher at ETH Zurich, a university in Switzerland, who is studying the impacts of the program. “If that payment wasn’t there, you can imagine that a lot of people would continually clear the forest,” he told Vox. 

To date, the government has more than 20,000 contracts for payments with landowners, a spokesperson told Vox, and the program currently covers 540,000 hectares of forest — an area a little smaller than the state of Delaware. 

Was paying landowners the secret to Costa Rica’s success?

For years now scientists have debated about whether or not these sorts of payment schemes actually work. Yet despite more than two decades of research, the answer is still elusive.

I reviewed more than a dozen studies from Costa Rica, and on the whole, they suggest that the program has had a modest positive impact on forests overall — but not a big one. A comprehensive 2008 study by the World Bank, in the northeastern region of Sarapiquí, determined that the program led to “a small but statistically significant increase in the area of forest conserved.” Other studies that analyzed the early years of the program indicate that it didn’t reduce deforestation or only worked in some regions. 

A more current analysis, led by the Inter-American Development Bank, detected a drop in deforestation on land that was part of the program. Yet the results were only significant (statistically speaking) for the first year after enrollment. There also wasn’t much deforestation to begin with. A 2024 paper, meanwhile, found that forest cover increased on farmland after it was enrolled in the program, but the study couldn’t definitively attribute those increases to the payment system. 

Then there’s this new study — an analysis, led by Delgado of ETH Zurich, that looks beyond forests to the wildlife within them. The research compares the biodiversity present on land inside and outside the payment program to healthy baseline forests in northwest Costa Rica. And it does so using sound. A healthy tropical forest produces a distinct, complex noise, comprising the calls of frogs, birds, and insects. Damaged ecosystems sound quieter and simpler. 

Delgado and his collaborators put microphones in different landscapes and analyzed the sounds they picked up. As they discovered, land in the payment program — on which forests were naturally regenerating on old farmland — were far more similar to healthy, old forests than to pastures that were not enrolled in the program. You can actually listen to some of the recordings here. “It’s a strong signal that [the payment program] is working for biodiversity,” said Laura Villalobos, a Costa Rican economist at Salisbury University, who was not involved in the study. 

There’s no silver bullet for protecting forests and biodiversity

The major drawback of many studies on Costa Rica’s pioneering payment program — including this new one — is that they don’t show that the forests or biodiversity have recovered because of the program. “What’s really challenging is the issue of causality,” said Hilary Brumberg, a doctoral researcher at Stanford University, who was not involved in the acoustics study. “There are just so many confounding factors,” said Brumberg, who studies Costa Rica’s forests.

There are many other reasons why forests in Costa Rica may have grown back. In 1996, for example, the government effectively banned deforestation in the country, making it illegal to convert natural forests to other kinds of land (though some logging is still permitted). Around the same time, the price of beef collapsed. That made clearing land for cattle less profitable and caused some landowners to abandon their pastures. Meanwhile, the country’s ecotourism industry ballooned, providing incentives to keep the country’s iconic forest ecosystems intact. 

Importantly, Costa Rica also has a more pervasive environmental ethic compared to other forested nations. In fact, research suggests that some people join the payment program not for the money but because they want to contribute to forest conservation as a public good. 

Obviously, something is working. Costa Rica is green again. But the payment program has likely played only a small part in the country’s success. 

That’s consistent with research beyond Costa Rica, which finds that compensating landowners for ecosystem services has a positive but small impact. Ultimately, these sorts of programs haven’t been the solution to deforestation that environmental advocates were hoping for, said David Simpson, a now-retired environmental economist. “Trying to make nature valuable, it turns out, has had a disappointing track record,” Simpson wrote in 2018. 

In response to a request for comment, Karla Alfaro Rojas, director of the Department of Institutional Communications for the Costa Rican government, said, in an email: “Costa Rica doesn’t have to prove anything to anyone. We are an international leader in financial mechanisms and forest cover restoration.”

In a world with so many environmental problems, perhaps it seems unproductive to critique a program that is, if anything, helping conserve tropical forests. But there is an important lesson here: No one solution, no one model, will solve a problem as difficult as deforestation. Costa Rica was successful because it had all of the right pieces in place — strong policies, favorable economics, growing non-extractive industries, and, perhaps most importantly, political will.