Heat-related deaths in a vulnerable community in Indonesia have been linked directly to nearby deforestation by new research published in The Lancet.

The research by US-based The Nature Conservancy (TNC) and scientists from the University of Washington and Indonesia’s Mulawaran University focused on the Berau region of East Kalimantan in Indonesia, where 4375 km² of forested land was cleared between 2002 and 2018, the equivalent of 17 percent of the whole area.

The researchers used data from satellite monitoring of forest cover, temperature, and population, alongside intelligence from The Lancet’s Global Burden of Disease reports to estimate the impacts of deforestation and climate change on deaths due to heat exposure, and the effects of deforestation and climate change on unsafe work conditions.


Local deforestation, combined with climate change, had already caused mean daily maximum temperatures to increase by 0.95°C, they found, which in turn had led to an eight percent increase in mortality between 2002 and 2018.

Researchers projected that the region could ultimately experience an estimated 17–20 percent increase in deaths, and up to five hours a day where temperatures are unsafe to work in by 2100, compared with 2018, if temperatures rise by 3°C compared with pre-industrial levels.

A 2019 study in the same region found that outdoor labourers worked, on average, 6.5 hours a day, and are already shifting work schedules to avoid the hottest times of the day.


The study is significant because it is believed to be one of the first-ever studies to reveal how temperature rises driven by climate change and local deforestation are already increasing heat-related deaths among rural communities in a tropical country.

A growing body of research indicates that in tropical countries, both climate change and deforestation are increasing temperatures and heat exposure, but the combined risks of these changes have so far been underappreciated, according to the study.

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