A new research paper has indicated that tropical forests are not working nearly as well as previously believed in absorbing greenhouse gas emissions.
That's because these forests have been degraded by fires and a range of activities, reducing their capacity to do this by 626 percent between 2000 and 2013.
University of Queensland James Watson is a coauthor of the study, which was published in Science Advances.
"Recent science has shown that 25 percent of all emissions that are sent up to the atmosphere are sucked back through forests around the world. So that's extraordinary," Watson says in a Queensland University video on YouTube (see below.)
"What the carbon accounting has done to date is actually just treated forests as intact or completely degraded. Cleared or intact," he continued. "That's useful and it's been able to help us understand the value of forests. So we know now that 25 percent of all emissions are absorbed by forests, based on accounting.
"But it's simplistic. Not all forests are the same. In fact, what we found is 80 percent of forests are damaged in some ways by fires, by roads, by mining, by agricultural activity. And if you account for those damaging processes, we find that we're actually miscalculating how much carbon sequestration and storage is occurring by a massive 626 percent."
The Amazon rain forest was traditionally relatively fire-resistant, due to the humidity and natural moisture. But more frequent and intense droughts and human activity have led to more fires in the 21st century.
"When trees have less water during droughts, they shed extra leaves or die, leaving leaf litter and detritus on the forest floor," the National Oceanic and Atmospheric Administration stated in August. "Without a dense canopy to retain moisture, much of the forest’s humidity is lost. Additionally, the practice of 'selective logging' of specific tree species and 'slash and burn' agriculture opens the canopy further, which also dries out the understory and forest edges."
Watson pointed out that the Paris Agreement, which was reached by 195 countries in 2015, calls for minimizing climate change by 2050.
But the current accounting of carbon sequestration in tropical forests isn't necessarily helping to accomplish that objective.
"This is a special time that we can actually go out and proactively protect those last intact forests," Watson declared. "And we've got to remember, intact forests are not just important for climate change. They're extremely important for biodiversity concentration.
"Many imperilled species are not found anywhere else except for those large intact places around the planet. And the second thing is that they're the homes to Indigenous people."
He also noted that the study only focused on tropical forest and not northern boreal forests, which are incredibly important in addressing climate change.
"They sequester more carbon and store more carbon than all forests in the tropics," Watson stated. "We have ignored them to date and we have to account for them to get a really full picture of the consequences of damaging forests globally."