SINGAPORE (The Straits Times/ANN): More people in South-East Asia are dying from heat worsened by deforestation than in the Congo or Amazon rainforests, despite losing a smaller total area of forest than in the Americas, a recent study led by a British university has found.
Every year in South-east Asia, around 15,680 rural residents die of heat-related complications worsened by deforestation, compared with 9,890 for the tropical regions of Africa and 2,520 for the Americas.
Between 2001 and 2020, South-east Asia lost about 490,000 sq km of vegetation, while tropical Central and South America lost about 760,000 sq km of forest.
"South-east Asia has lost a smaller total area of tropical forest, but has higher population density... leading to higher heat-related mortality," said Dr Carly Reddington from the University of Leeds, who is the lead author of the study.
She added that Latin America has seen the greatest forest loss, but the death toll is lower because fewer people live in the deforested areas.
The study, published in scientific journal Nature Climate Change in late August, found that over 20 years, climate change and deforestation increased South-east Asia's temperature by 0.72 deg C.
Forests not only sustain life and absorb planet-warming carbon dioxide, they also have a cooling effect on people. While the canopies provide shade, the leaves release water vapour into the air and remove some heat, much like humans sweating to cool their bodies.
When trees are cut down, this cooling effect is reduced. When shade is gone, more sunlight hits the ground directly and the land can become drier and darker, absorbing more heat, explained Dr Reddington.
"This combination leads to significant local warming, sometimes even hotter than the warming caused by global climate change over the same period," she added.
Dr Reddington and her team used satellite data to calculate how much temperatures changed in tropical forest areas between 2001 and 2020, comparing deforested areas against intact areas.
The satellite findings were then combined with existing health data on how sensitive a population is to heat-related deaths.
Alongside over-exertion, exposure to high temperatures can lead to heatstroke and organ damage for outdoor workers.
The regions they work in could also have limited access to cooling and healthcare, said Dr Reddington.
The paper added that vulnerable populations, including indigenous communities, often live near deforested areas and have limited access to resources and infrastructure needed to cope with rising temperatures and environmental changes.
A separate 2021 study found that deforestation in the Berau regency of Indonesia between 2002 and 2018 accounted for more than 100 additional heat-related deaths each year. Unsafe work duration also increased by 20 minutes each day.
Over the 16 years studied, more than 4,300 sq km of land was cleared in Berau, East Kalimantan - about six times larger than the total land area of Singapore. The study was led by environmental non-profit The Nature Conservancy.
Other studies have shown that the productivity and cognitive performance of rural workers in East Kalimantan were substantially lower in deforested areas than in forested ones, Dr Reddington noted.
"Tropical deforestation doesn't just affect the environment - it could directly harm human health, especially in communities least equipped to cope. Protecting tropical forests is not only vital for the planet, but also for safeguarding lives," she said.
Dr Reddington urged governments of tropical nations to strengthen forest protection laws, invest in reforestation and improve heat management solutions - such as providing shaded workspaces, cooling centres and better access to healthcare in high-risk areas.
"Climate finance should prioritise forest conservation and health resilience in the tropics, where the risks are greatest and resources are often limited," she added.
Commenting on the recent study, Associate Professor Kimberly Fornace from the NUS Saw Swee Hock School of Public Health said: "We need to consider land cover when developing early warning (for extreme heat). We have seen this with urban heat in cities and there is a need to consider effects on rural populations as well."
Prof Fornace said that further on-the-ground studies need to be done to augment the paper's findings. For one thing, the impacts of rising heat on individuals are not always clearly captured by secondary health data, because the effects can vary significantly in different populations.
"While the authors have done a nice job to highlight the scale of deforestation-related heat health impacts, there is still a need for more local population-based health studies," she said. - The Straits Times/ANN