Rainforests are rain-making machines worth tens of billions of dollars to farmers.
A new study puts a price tag on forest-generated rainfall, making the economic case for protecting tropical forests as deforestation rises.
February 25, 2026
Tropical rainforests get that name because it rains a lot in these places. But they deserve it for another reason as well: They make rain.
By absorbing water and then transpiring it into the atmosphere, a single hectare of tropical rainforest in the Brazilian Amazon can generate approximately 2.4 million liters of rain per year, enough to fill an Olympic-size swimming pool, according to new research in the journal Communications Earth & Environment.
By absorbing water and then transpiring it into the atmosphere, a single hectare of tropical rainforest in the Brazilian Amazon can generate approximately 2.4 million liters of rain per year, enough to fill an Olympic-size swimming pool
While not everyone cares about filling swimming pools, a vastly more important and economically valuable metric is the crops this rain could water. In Brazil alone, the Amazon rainforest generates rainfall worth approximately $20 billion dollars per year if it went to agricultural activities, the scientists reported.
“Tropical deforestation is increasing, despite international efforts to halt forest loss. Our work highlights the vital role of tropical forests in producing rain,” said Jess Baker, a climate scientist at the University of Leeds in the United Kingdom and an author of the new paper.
It’s not news that rainforests produce rain. A paper last year found that deforestation caused almost 75% of the decline in rainfall during the Amazonian dry season in the last four decades. But estimates for the economic toll have been all over the place. One study put it at up to $1 billion per year in agricultural losses. A report submitted to the Brazilian Supreme Court found that agricultural earnings in the most rain-dependent regions totaled more than $60 billion per year.
deforestation caused almost 75% of the decline in rainfall during the Amazonian dry season in the last four decades.
To come up with more precise estimates for just how much rain comes from rainforests, and how much it’s worth, Baker teamed up with colleagues at Leeds, Brazil’s University of Amazonas, and the carbon finance program at Dutch banking giant Rabobank.
The work involved running massive computer models that underpin much of what scientists understand about how the atmosphere and the earth interact to shape such basic forces as precipitation and temperature. The researchers looked at how rainfall in tropical regions changed as trees were replaced by grassland in the models, a common fate with deforestation. The models both looked at reconstructions of historical patterns and simulated scenarios of different levels of forest loss. The scientists compared the results from those models to estimates derived from satellite observations.
Protecting forests is not just about biodiversity—it is now about protecting rain.
The researchers concluded that around the world, every percentage point of tropical forest that disappeared equaled a loss of 2.4 millimeters (mm) per year in rainfall. In the Amazon, the effect was even more pronounced, at 3 mm per year.
While that might not sound like much, it adds up quickly. In Brazil, it amounts to around 300 liters of water each year for every square meter of Amazon forest, a place with 3.3 trillion square meters of rainforest. That’s a lot of swimming pools.
To put a dollar figure on how much all this water is worth, the researchers multiplied the forest-generated rainfall by an estimated cost of water for Brazilian agriculture, which a Brazilian agency reported as around 2 cents per cubic meter. Do the math, and you end up with the rainforest generating rain worth around $20 billion per year to farmers, give or take $7 billion based on model uncertainties. Looking at deforestation rates, the scientists estimate the region has already lost nearly $5 billion worth of rainfall in recent decades. And none of this counts the other benefits of all this rain – driving hydropower turbines, providing drinking water, filling rivers used by wildlife and cargo ships, etc.
Still, “this is the most comprehensive and robust evidence to date of the value of tropical forests’ rainfall provision,” Baker said.
The value of all that forest-generated water dwarfs the amount being spent to keep those forests from disappearing. For example, the new calculations show that Brazil’s network of officially protected forest generates around $13 billion worth of rain each year. That’s more than 50 times the money the Brazilian Ministry of the Environment dedicates to managing these areas, according to the researchers.
The new calculations could help buttress the math behind efforts to attract money to keep forests standing.
“Tropical forests make it rain, supplying water that is essential for agriculture. Recognizing that crucial connection could ease tensions between agricultural and conservation interests while building broader support for protecting forests overall,” said Callum Smith, a Leed’s researcher and co-author who studies how forest loss affects climate.
There is growing attention to such efforts to pay for the benefits of standing forests, whether because rainforests suck greenhouse gases from the atmosphere, harbor vast biodiversity or generate rain. Last year, at the annual United Nations climate summit held in Belém, Brazil, Brazilian president Luiz Inácio Lula da Silva unveiled a project called the Tropical Forest Forever Facility. It aims to raise $125 billion that would pay countries or landowners to leave their forests intact.
It aims to raise $125 billion that would pay countries or landowners to leave their forests intact.
When you consider the annual value just of rainfall in the Brazilian Amazon alone, that might seem like a bargain.
Baker, et. al. “Quantifying tropical forest rainfall generation.” Communications Earth & Environment. Feb. 17, 2026.