No, The Amazon Does Not Produce 20 Percent Of Our Oxygen

Sunrise in the Amazon rainforest. Al'fred/Shutterstock

Waves of fire are currently washing over the Amazon rainforest. As the shocking images and videos are a testament to, the fires are undeniably an ecological disaster that will spell tragedy for the wealth of biodiversity and the millions of people who have lived alongside the forest for millennia. Since the Amazon regulates part of Earth’s carbon cycle, water cycle, and climate, it’s a disaster for the whole world too. 

However, amid the welcome concern on social media, misinformation has taken root. A handful of media outlets, public figures, and even world leaders have propagated the claim that the trees in the Amazon rainforest generate over 20 percent of our planet’s oxygen.

“Our house is burning – literally,” French President Emmanuel Macron tweeted last Thursday. “The Amazon rainforest – the lungs which produce 20 percent of our planet’s oxygen – is on fire. It is an international crisis. Members of the G7 Summit, let's discuss this emergency first order in two days!”

This simply isn’t true. Of all the reasons to be shocked and dismayed at the ongoing Amazon fires, we don't need to worry about our oxygen supplies running dry.

“The 20 percent figure IS too high,” Professor Michael E Mann, one of the world’s most prominent climate scientists tweeted on Friday. “True number closer to 6 percent as per Jon Foley… and even this is misleading because oxygen levels wouldn't actually drop by 6 percent if we deforested the Amazon.”

Main reservoirs and fluxes (in 1012 mol/yr) of the modern global O2 cycle on Earth. Pengxiao Xu/Wikimedia Commons CC BY-SA 4.0

Although forests create a lot of oxygen through photosynthesis, much of this oxygen is consumed by the respiration of living organisms, namely the incredible array of insects, fungi, and bacteria that feast on plant matter and decompose it (shown in the diagram above).

Microscopic phytoplankton that live in the world’s oceans produce huge amounts of oxygen through photosynthesis. However, once again, most of this is ingested back into the marine biosphere’s own oxygen cycle through the process of respiration, resulting in a net of almost zero breathable oxygen. 

The atmosphere has been composed of approximately 20.95 percent oxygen for millions of years. In reality, the total bank of breathable oxygen in the atmosphere remains almost undisturbed by land use, at least in terms of our human timescale, and is more swayed by colossal geological-scale changes.  

“Even if all organic matter on Earth were burned at once, less than 1 percent of the world's oxygen would be consumed,” Scott Denning, professor of atmospheric science at Colorado State University, writes in an article for The Conversation.

“There's enough oxygen in the air to last for millions of years, and the amount is set by geology rather than land use.” 

It’s important to address these erroneous facts, not to douse the concern over the situation, but to ensure the issue is not distracted from or negated. Brazilian President Jair Bolosnaro has dismissed international concern about the Amazon rainforest fires as a misinformation campaign spread by old “colonial” world powers. If silly errors, such as this "20 percent of Earth's oxygen" statistic, are not kept in check, it’s an easy win for those who cry “fake news” at their convenience. 

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