The world’s largest rainforest has previously been a carbon sink — absorbing more CO2 than it releases — but the study, published in the journal Nature on Wednesday, found that parts of Amazonia are helping drive the climate crisis.
“We need these carbon sinks, we are counting on them,” John Smol, a professor in the biology department at Queen’s University and Canada Research Chair in Environmental Change, said. “When one of the carbon sinks can turn into a carbon source, well, that’s a nightmare scenario and we now have to cut even more greenhouses gases.”
Although he described the study as incredibly worrisome, he applauded its impressive detailed work in showcasing how parts of the Amazon rainforest are accelerating climate change due to deforestation, mining and agriculture.
“We know that deforestation and burning forests causes climate change,” he said. “But this study shows the indirect effects, too — the forest that has not been cut down … there is still physiological stress on trees that are left. It affects them to the point where they are far less efficient carbon sinks.”
Most of the emissions were caused by human-caused fires (in order to clear land for agriculture), according to the study. But it also found that even without fires or deforestation, hotter temperatures and droughts have caused parts of the forest to become a source of CO2, rather than a sink.
To gather this information, the scientists, from Brazil’s National Institute for Space Research, flew small planes every few weeks over four main sites of the Brazilian forest to measures CO2 levels over a period of nine years.
The researchers discovered that some areas of the rainforest are becoming “a steadily increasing source” of carbon. The eastern part of the Amazon, which is around 30 per cent deforested, emitted 10 times more CO2 than the western region. The western region is around 11 per cent deforested.
“This carbon sink seems to be in decline,” the study said. “Over the past 40 years, eastern Amazonia has been subjected to more deforestation, warming and moisture stress than the western part, especially during the dry season, with the southeast experiencing the strongest trends.”
The importance of the Amazon
The Amazon rainforest, which spans 6.9 million square kilometres (about 40 per cent of South America), is home to thousands of trees and plant species and drains two billion tons of CO2 per year from the atmosphere.
It has been deemed one of Earth’s best defences against climate change.
But the study showed the Amazon now accounts for more than one billion metric tons of emissions every year — and researchers say that number could continue to increase.
Another 2020 study published in the journal Science Advances found that the entire Amazon rainforest, rather than just parts of it, may soon become a net carbon source instead of a sink — and it could happen by 2050 or sooner.
The continued destruction of the rainforest has caused roughly 17 per cent of the rainforest to be destroyed over the past 50 years and put thousands of animals at high risk of extinction.
“The Amazon is absolutely under siege,” Kerry Bowman, a professor of bioethics and global health at the University of Toronto, said. “The situation is profoundly serious to all of us. It has short and long-term implications for the health and well-being of the entire planet and including you and I.”
'We're sleepwalking to disaster'
In Brazil, deforestation has surged since right-wing President Jair Bolsonaro took office in 2019, reaching a 12-year high last year and drawing international outcry from foreign governments and the public.
Bolsonaro has called for mining and agriculture in protected areas of the Amazon and has weakened environmental enforcement agencies, which environmentalists and scientists say has directly resulted in the rising destruction.
What is happening in the Amazon has the potential to create massive climate change globally — and even impact weather in North America, Bowman said.
“We need our politicians to continue and put more pressure to put more pressure on the Brazilian government to protect and stabilize the Amazon. “The government of every nation, including Canada, absolutely must take responsibility.“
Smol agreed, adding that studies like the one released Wednesday, show we are at a tipping point and need to act quickly.
“We’re sleepwalking to disaster,” Smol said. “And you can link what is happening in the Amazon to Canada, you just need to go west and see the forest fires going on,” he said.
–With files from Reuters.