Science

Amazon rainforest fires: Why NASA fears new wildfires will 'accelerate warming' of climate


The Amazon in Brazil is ablaze with more than 75,000 wildfires tearing through the rainforest since the start of the year. Wildfire data collected by Brazil’s National Institute for Space Research (INPE) shows the number of fires has almost doubled on last year’s figures. The Amazon fires are visible from space as thick black smoke belches from the “lungs of the world”. The Amazon rainforest accounts for 20 percent of the world’s oxygen, leading environmental groups to label the wildfires a climate crisis. 

But according to space agency NASA, there is another wildfire threat brewing in the boreal forests of Canada. 

A NASA-funded study of wildfires in the Canadian Northwest Territories found a ticking time bomb threatening to release generations-old carbon deposits trapped in the soil. 

This part of Canada suffered devastating wildfires in 2014, which had an impact on the natural processes that bury and trap carbon in the ground. 

With the increased risk of forest fires from climate change, NASA said the trapped carbon dioxide could be released back into the atmosphere, “potentially accelerating warming”. 

The US space agency said: “As Earth’s northern regions grow warmer and drier due to climate change, fire seasons are getting longer and fires are becoming more severe.  

“Boreal forests have long been thought to absorb more carbon from the atmosphere than they release into it, making them carbon ‘sinks’. 

“But if bigger and more frequent fires start burning legacy carbon, these forests could start releasing more carbon than they store.” 

Environmental conservation groups like the World Wide Fund for Nature (WWF) believe incidents like the Amazon rainforest fires are made worse by global warming. 

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In response to the Amazon fires, the WWF said climate change is the “biggest environmental crisis of our time”. 

The group directly blamed the fires on deforestation for farmland and crops. 

The WWF said: “While natural wildfires are not unusual at this time of the year, the sheer scale and intensity of these fires is exceptional, and the direct result of increases in deforestation rates by farmers going largely unchecked by Brazilian government.” 

With the threat of more carbon dioxide being released into the atmosphere, NASA said wildfires will become more frequent, in turn, fuelling the number of young forests releasing “legacy carbon”. 

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Legacy carbon is the oldest carbon trapped under a layer of thick and organic material on the forest floor. 

Researchers from Canada and the US found old forests and wet forests did not burn away the protective layer easily. 

In younger and drier forests, however, the protective layer is much shallower and easier to burn away in a wildfire. 

NASA said: “Carbon dioxide is a greenhouse gas, so releasing more of it into the atmosphere could affect the balance of the global carbon cycle and contribute to climate change.” 

Boreal forests populate vast swathes of North America, Europe and Canada. 

Approximately 30 percent to 40 percent of the world’s land-based carbon is stored in these forests.

When the Canadian forests burned in 2014, scientists estimate about 8.8 million tons of carbon were released into the atmosphere. 

The study’s co-author Brendan Rogers, a scientist at Woods Hole Research Center, said: “By defining and analyzing ‘legacy carbon,’ this paper offers a new way to think about long-sequestered carbon stocks in boreal forests and how vulnerable they are to being burned during increasingly frequent and severe wildfires. 

“This tool helps us understand when burning goes ‘outside the norm’ from a historical perspective and begins to combust carbon stocks that survived past fires.” 

The wildfire stay was published in the journal Nature.  



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