A study published a few weeks ago in Nature Climate Change concluded that deforestation has killed more than half a million people in the past two decades, between 2001 and 2020. A frightening figure, even though it is probably underestimated. It only refers to tropical countries and takes into account only deaths related to heat. Yet we know that deforestation—mainly driven by agricultural expansion and logging—causes multiple harms not only to human life but also to the ecosystems that sustain it. The destruction of biodiversity, disruption of the hydrological cycle, and extreme weather events triggered by deforestation are also present or future causes of mortality.

This research, carried out by scientists from Brazil, Ghana, and the United Kingdom, focuses on one of the most visible effects of deforestation: the rise in land surface temperature. “Local warming associated with deforestation can be immediate and substantial—equivalent to or greater than that expected from a century of global climate change under a high-emissions scenario,” the authors write. And we know very well that heat kills. As reported earlier this summer on Valori, another study detected a rise in heat-related mortality in several European cities. So imagine what happens in the tropics.

Deforestation kills by heating up the planet

Deforestation is raising temperatures in the rainforests of the Amazon, the Congo, and Southeast Asia because it reduces shade, decreases rainfall, and increases the risk of fires. “Tropical deforestation induces local warming and represents a potential risk to human health, having been linked to high heat stress and a reduction in safe outdoor working hours,” the researchers note. According to the study, deforestation accounts for more than one-third of the global warming experienced by people living in affected regions. It adds to the other devastating effects of climate change.

“Satellite data analysis shows that tropical deforestation between 2001 and 2020 exposed 345 million people to local warming, with a population-weighted daytime surface temperature increase of 0.27 °C,” write the authors. “For 2.6 million of them, the additional warming caused by deforestation increased their heat exposure by 3 °C.” In many of these cases, such exposure proved deadly. “Heat stress can negatively affect mood and mental health, impair physical performance, and reduce labour productivity. Furthermore, heat exposure is associated with higher morbidity and mortality risks from cardiovascular and other diseases.”

And it will continue to claim lives by devastating the social fabric of affected countries

The study estimates 28,330 deaths per year between 2001 and 2020, for a total of more than half a million people. More than half of these deaths occurred in Southeast Asia, due to higher population density in areas vulnerable to heat. About a third occurred in tropical Africa, and the rest in Central and South America. But that is not all. As the authors explain, the effects of heat linked to deforestation are long-term and affect the entire social structure of the countries concerned. “The effects of climate change on human health are exacerbated by socioeconomic and demographic factors. […] In low-income countries with limited adaptive capacity, including many tropical nations, the loss of work capacity due to heat stress can have significant economic consequences and increase overall poverty.”

See, Tristi tropici: in 20 anni mezzo milione di persone uccise dalla deforestazione