Since the tropics are becoming hotter due to climate change and deforestation, the ability of outdoor workers to perform their jobs safely is increasingly reduced. This is the conclusion of research led by Duke University and published in the journal OneEarth.
The study suggests that in recently deforested locations, almost five million people lost at least half an hour of safe outdoor work time per day.
“There is a huge disproportionate decrease in safe work hours associated with heat exposure for people in deforested locations versus people in forestated locations just over the past 15 or 20 years,” said study lead author Luke Parsons, a climate expert at Duke.
“There is a small amount of climate change that has happened over the same 15-year period, but the increase in humid heat exposure for people living in deforested relative to forested locations was much larger than that from recent climate change.”
Since trees block out the sun’s radiation and cool down the air through evapotranspiration (a process when plants transport water from the soil and evaporate it through the leaves), deforestation is associated with an increase in local temperatures.
“The trees in the tropics seem to limit the maximum temperatures that the air can reach. Once we cut those trees down, we lose that cooling service from the trees, and it can get really, really hot,” explained Parsons.
“In the Brazilian Amazon, for example, where huge swaths of the rainforest have been cleared in the last 15 or 20 years, the afternoons can be up to 10 degrees Celsius warmer than forested regions.”
Using satellite data and meteorological observations, Parson and his colleagues tracked the temperature and humidity levels in 94 countries with tropical forests in America, Africa, and Asia, from 2003 to 2018. They estimated that, in recently deforested areas, approximately five million people lost about half an hour, and 100,000 lost up to two hours of safe outdoor work time per day.
“I think the research has a positive message and a negative message. The negative message is that if we cut down trees, we not only cause problems for the ecosystem and global carbon emissions, but we also lose local cooling services that provide a comfortable and safe place to work.”
“But the positive message is that if we can prevent forest loss, we can maintain cooling services along with all the other benefits forests provide. Importantly, the relationship between the health of the forests and nearby people offers an additional, locally relevant reason to prevent tree loss,” Parsons concluded.