Tropical forests, often hailed as the lungs of our planet for their role in carbon storage, possess an equally vital yet underappreciated function: generating rainfall that sustains ecosystems, agriculture, and economies across vast regions. A groundbreaking study led by researchers at the University of Leeds offers the most comprehensive quantification to date of the enormous volume of rainfall produced by these forests and attributes a staggering economic value to this service. By blending advanced satellite data with cutting-edge climate modeling techniques, the team has illuminated the profound hydrological and economic impact of tropical forest evapotranspiration, revealing implications that could reshape global conservation policies.
Evapotranspiration—the combined process of water evaporation from soil and plant transpiration—serves as nature’s atmospheric engine. Solar energy drives moisture from leaves into the atmosphere, where it contributes to cloud formation and subsequent rainfall, extending well beyond the forest boundaries. Drawing on high-resolution satellite observations collated with a suite of next-generation climate models, the Leeds researchers calculated that each hectare of tropical forest annually produces roughly 2.4 million liters of rainfall—roughly the volume of an Olympic-sized swimming pool. This moisture output translates to approximately 240 liters per square meter every year across the tropics, with even higher values in the Amazon basin nearing 300 liters per square meter.
The team’s innovative methodology addressed previous uncertainties surrounding the magnitude of forest-driven rainfall. Traditional models often struggled to parse the complexities of atmospheric moisture transport and precipitation dynamics, but by integrating observational data with sophisticated simulations, the study delivers a robust and unprecedented empirical foundation. This fusion of remote sensing and computational climate science represents a leap forward in ecological hydrology, establishing concrete links between intact forests and downstream rainfall patterns critical to both natural habitats and human endeavors.
Importantly, the research advances beyond hydrological quantification by incorporating an economic lens. By estimating the value of rainfall to the agricultural sector, the study places an annual figure of approximately US$20 billion on the rainfall generated by the Amazon’s tropical forests—an enormous sum that dwarfs current financial incentives aimed at rainforest conservation. Such a valuation reframes tropical deforestation not merely as an environmental crisis, but as a significant economic and food security threat with cascading impacts on regional markets and livelihoods. The economic losses already incurred due to the destruction of roughly 80 million hectares of the Amazon could reach US$5 billion annually in reduced rainfall benefits alone.
Agricultural productivity, heavily dependent on these precipitation patterns, emerges as an especially vulnerable sector. The study reveals that key crops such as cotton and soybeans require moisture quantities equating to rainfall produced by multiple hectares of forest—cotton needing moisture equivalent to that generated by two square meters of intact forest for every square meter cultivated. This insight underscores the intricate dependence of agriculture on forest ecosystems, challenging simplistic conservation narratives by revealing the symbiotic relationship between land use and forest hydrology.
The socio-economic ramifications extend well beyond food production. Rainfall deficits induced by forest loss jeopardize hydropower generation and potable water supplies, imperiling energy security and human health in many parts of tropical countries. River transport, a crucial logistical artery especially in remote Amazonian regions, faces operational constraints as water levels drop. Furthermore, reduced precipitation compromises remaining forests’ carbon sequestration capabilities, potentially accelerating global climate feedback loops.
Brazil’s economy, with approximately 85% of its agriculture reliant on rainfall, encapsulates the acute vulnerability inherent in this interdependence. Recent climate variability manifesting as shorter or delayed wet seasons has already translated into diminished yields for soy and maize in deforested Amazonian regions. This sensorium of ecological and economic distress illustrates a dangerous feedback cycle: forest loss reduces rainfall, which then imperils agriculture, motivating further land-clearing for alternative productive uses. The Leeds study’s findings highlight the urgency of disrupting this destructive spiral.
Despite international pledges such as the 2030 deforestation halt targets, tropical forest loss continues unabated, primarily driven by agricultural expansion and infrastructural development. The study’s authors emphasize that existing economic and legal frameworks often neglect the value of rainfall generation services—an oversight that critically undermines efforts to protect forested landscapes. By integrating hydrological services into valuation models and policy discussions, stakeholders could foster broader consensus and mobilize greater investment in conservation.
Dr. Jess Baker, leading author and climate scientist at the University of Leeds, points to the transformative potential of recognizing forests as rainfall engines. “Our findings provide the most robust evidence yet of the pivotal role tropical forests play in sustaining regional water cycles. Beyond carbon storage, their hydrological services underpin agriculture and economies worth billions annually—figures that urgently call for revised conservation priorities,” she explains. This novel valuation introduces a compelling economic argument that transcends traditional environmentalist appeals, potentially aligning agricultural interests with forest preservation imperatives.
Co-author Dr. Callum Smith further stresses the bridging role such scientific evidence could play in mitigating conflicts between conservation and agricultural stakeholders. Highlighting forests’ capacity to indirectly support crop water needs through rainfall provision, he describes the findings as a critical stepping stone toward reconciling developmental goals with ecological stewardship. The acknowledgment of tropical forests’ hydrological influence opens avenues for integrated land-use planning that promotes both food security and ecosystem resilience.
Beyond the Amazon, the study’s implications resonate across tropical forest regions worldwide, from Central Africa to Southeast Asia. While the specific rainfall volumes and economic valuations will vary regionally, the underlying processes of evapotranspiration and moisture recycling remain universal. Thus, policy frameworks that internalize the value of forest-generated rainfall could catalyze transformative global partnerships, balancing agricultural demands with ecosystem preservation in climate-sensitive contexts.
The University of Leeds’ study, published in Communications Earth & Environment, marries computational simulation with observational rigor, applying a multidisciplinary approach that pioneers pathways for future research. By quantitatively linking forest evapotranspiration to extensive economic outcomes, it underscores the interconnectedness of ecosystem services, climate systems, and human economies at scales hitherto poorly understood. This nexus invites a reframing of tropical forests not solely as carbon sinks but as indispensable hydrological infrastructures vital for planetary sustainability.
As climate change and global population growth intensify pressures on land and water resources, the critical role of tropical forests in generating regional rainfall and sustaining agriculture cannot be overstated. This research challenges policymakers, conservationists, and agribusinesses to recognize the far-reaching consequences of forest destruction. It reinforces that safeguarding remaining tropical forests is not only an environmental imperative but also an economic necessity critical to water security, energy production, food systems, and ultimately human well-being.
Subject of Research: Not applicable
Article Title: Quantifying tropical forest rainfall generation
News Publication Date: 17 February 2026
Web References: http://dx.doi.org/10.1038/s43247-025-03159-3
References: Baker et al., 2026. Quantifying tropical forest rainfall generation. Communications Earth & Environment.
Image Credits: Not provided
Keywords: Ecology, Land use, Environmental policy, Natural resources
