The Earth’s lungs are on fire. They’re burning up: Some version of that has been said by politicians, journalists, celebrities and members of the public since the destructive blazes began to engulf Brazil’s rainforest more than three weeks ago
Almost all the oxygen in the air is produced by plants through photosynthesis, and since a large amount of photosynthesis happens in places like the Brazilian rainforest, that claim has gained traction.
Although the fires pose a danger to the massively biodiverse area, some experts are now offering another view, saying they do not threaten the planet’s oxygen supply.
According to Scott Denning, professor of atmospheric science at Colorado State University, most of the oxygen that gets produced by photosynthesis each year is consumed by fires and living organisms, with trees shedding dead leaves and twigs that in turn end up feeding insects and microbes.
“Forest plants produce lots of oxygen, and forest microbes consume a lot of oxygen. As a result, net production of oxygen by forests — and indeed, all land plants — is very close to zero,” Denning explained on Tuesday in a Scientific American essay.
Shanan Peters, a geologist at the University of Wisconsin at Madison, imagined what would happen if we burned every forest, blade of grass, bacteria and bird on Earth — basically everything except humans — in a presentation slide at a scientific convention in June.
After such a catastrophic scenario, the concentration of oxygen in the atmosphere dropped from 20.9 percent to 20.4 percent, according to The Atlantic.
“Virtually no change,” Peters said. “Generations of humans would live out their lives, breathing the air around them, probably struggling to find food, but not worried about their next breath.”
As Denning notes in his essay, tiny phytoplankton in the ocean generate half of the oxygen produced worldwide.
“The fact that this upsurge in deforestation threatens some of the most biodiverse and carbon-rich landscapes on Earth is reason enough to oppose it,” Denning concludes.