New research has unveiled a striking and sobering link between tropical deforestation and a significant rise in heat-related mortality among populations dwelling near these rapidly disappearing forests. The study, published in the prestigious journal Nature Climate Change, was carried out by a team of scientists led by Dr. Carly Reddington and Professor Dominick Spracklen at the University of Leeds’ School of Earth and Environment. Their findings indicate that tropical deforestation is not solely an environmental crisis but also poses a critical public health threat by escalating local temperatures and thus increasing heat exposure-driven deaths.
Tropical forests play a multifaceted and crucial role in regulating the Earth’s climate, acting as natural buffers against extreme temperature fluctuations. By providing extensive canopy cover, these forests reduce surface heat through shade and promote atmospheric moisture via evapotranspiration – a process where trees release water vapor into the air. Moreover, tropical trees sequester atmospheric carbon dioxide, mitigating the intensification of the greenhouse effect. When these forests are cleared or degraded, these cooling and carbon-absorbing mechanisms are lost, creating localized hotspots of elevated temperatures with far-reaching implications that propagate both regionally and globally.
Leveraging satellite data spanning from 2001 to 2020, researchers precisely mapped areas where tree cover was lost across vast tropical regions including Central and South America, Africa, and Southeast Asia. These spatial data were coupled with detailed land surface temperature measurements to quantify warming attributable specifically to deforestation. The team then cross-referenced these findings with high-resolution population distribution data, enabling them to estimate the number of people exposed to this additional heat stress. They further integrated mortality data to assess the health impacts, focusing on non-accidental deaths to isolate fatalities that could be linked to heat exposure rather than other causes.
One of the most alarming outcomes of this analysis is the estimate that over 300 million people residing within tropical regions are exposed to significant temperature increases directly tied to deforestation. This heightened exposure correlates with approximately 28,000 annual deaths that are attributable to heat stress induced by forest loss. The researchers attribute the disproportionate burden borne by communities living in close proximity to deforested areas, many of whom have limited access to healthcare, cooling infrastructures, and adaptive tools, exacerbating their vulnerability to rising heat.
In dissecting the underlying mechanisms, the removal of forest canopies eliminates a natural shading effect, causing increased solar radiation to reach the ground surface, which raises local air temperatures. The loss of evapotranspiration further decreases humidity levels and reduces latent heat flux, disrupting local energy balances and raising sensible heat. Additionally, deforestation accelerates the accumulation of greenhouse gases locally by curbing the carbon sink capacity of these forests, compounding the warming through radiative forcing effects. This feedback loop intensifies heat exposure, rendering affected areas hotter and more inhospitable.
Social and socioeconomic dimensions intertwine intricately with these environmental changes. Tropical deforestation often occurs near rural and economically disadvantaged communities where infrastructure to cope with extreme heat is scarce or non-existent. The absence of air conditioning and other cooling technologies amplifies heat vulnerability. Many inhabitants engage in outdoor labor during peak daytime temperatures, further elevating their risk of heat-related illnesses and fatalities. This constellation of environmental and social factors essentially creates hotspots of heat vulnerability with outsized human health impacts.
Region-specific analyses highlight stark examples, such as Indonesia, where over 48 million people face increased heat exposure related to deforestation. Similarly, 42 million people in the Democratic Republic of Congo and 21 million in Brazil are also affected. These figures underscore the global scale of the issue, emphasizing that tropical deforestation’s repercussions transcend environmental boundaries and deeply influence human well-being on a massive scale. Regions with high population densities adjacent to cleared forests demonstrate the most acute heat exposure and mortality risks.
In addition to stressing human health, tropical deforestation exerts profound adverse effects on biodiversity and ecosystem services. The local microclimate changes undermine the delicate balance that countless species rely on for survival. Changing water cycles due to decreased evapotranspiration alter rainfall patterns and soil moisture, further destabilizing regional climates and affecting agricultural productivity. These intertwined consequences represent a cascade of challenges that impede sustainable development efforts within tropical regions.
The methodology utilized in this study sets a benchmark for analyzing the intersection of environmental degradation and public health. Utilizing extensive satellite imagery combined with land surface temperature datasets allowed for precise attribution of localized warming to forest loss. When augmented by population distribution and mortality datasets, the research adeptly quantified the human cost of environmental change rooted in deforestation—a rarely quantified but profoundly significant dimension of climate science.
Importantly, the study’s results emphasize that conserving tropical forests is not only imperative for global climate mitigation strategies but also essential for protecting human health at local and regional scales. Forest protection initiatives can preserve natural cooling mechanisms, attenuating the severity of heat exposure events and thereby averting thousands of preventable deaths annually. This insight provides a compelling argument for integrating forest conservation with public health policies and climate adaptation planning.
Professor Spracklen emphasized the call to action stating that their findings strongly advocate for curbing deforestation with urgency. Recognizing the multifaceted benefits of intact tropical forests—including their role in stabilizing temperatures for nearby populations—can galvanize broader support among policymakers, stakeholders, and communities to prioritize forest protection. Such integrated approaches could foster resilience not only to ongoing climate change but also to the immediate, tangible risks of heat-related mortality linked to habitat destruction.
While this study sheds critical light on the direct human health implications of tropical deforestation, it also opens avenues for further investigation. Understanding how localized warming interacts with other social determinants of health, exploring mitigation pathways, and assessing the efficacy of reforestation and afforestation projects in reversing these trends are important next steps. As climate change progresses, interdisciplinary research bridging ecology, meteorology, and public health becomes increasingly vital to protect vulnerable populations worldwide.
In summary, tropical deforestation accelerates local warming by disrupting natural cooling processes, exposing hundreds of millions to dangerous heat levels, and causing tens of thousands of deaths annually. This research not only elevates tropical forest conservation as a climate priority but reframes it as a pressing public health imperative—underscoring the profound interconnectedness between environmental stewardship and human survival in a warming world.
Subject of Research: People
Article Title: Tropical deforestation is associated with considerable heat-related mortality
News Publication Date: 27-Aug-2025
Web References: https://www.nature.com/articles/s41558-025-02411-0, http://dx.doi.org/10.1038/s41558-025-02411-0
References: Reddington, C.L., Spracklen, D.V. et al. (2025). Tropical deforestation is associated with considerable heat-related mortality. Nature Climate Change. DOI: 10.1038/s41558-025-02411-0
Keywords: Climate change, Climate data, Deforestation rates
