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Topline: As news of the fires in the Amazon rain forest spread, sparking international outrage and condemnation, so too did a uncited statistic: The Amazon produces 20% of the world’s oxygen. French President Emmanuel Macron tweeted it. Actor Leonardo Dicaprio posted it on Instagram. CNN included it in its coverage.

The only problem? No one knows where the number came from, and it doesn’t appear to be true.

• Mathematically, it’s impossible for the Amazon to produce that much oxygen, said Jonathan Foley, the former executive director of the California Academy of Sciences and founder of Project Drawdown, a research group focusing on climate change. 
• Foley thinks the number could have originated from the fact that all tropical forests (including those in Africa and Indonesia) produce 20% of the oxygen from land-based sources.
• Combining land and ocean, which also produces oxygen, tropical forests only account for 10% of the world’s oxygen. Narrowing that down, Foley estimates it’s only possible for the Amazon itself to produce 6%.

Still, even without worrying about oxygen, the Amazon is important for the environment, Foley said. It stores carbon that, once released into the atmosphere through the act of burning, produces dangerous carbon dioxide emissions that warm the atmosphere and contribute to climate change. In fact, the Amazon stores 25% of the world’s carbon, according to a 2015 paper published in Nature. 

“The more carbon that can be taken out of the atmosphere and put into forms that are more stable is a good thing, and forest vegetation is one of those good ways to store carbon,” said Robin Chazdon, a professor at the University of Connecticut. 

The Amazon is also a hotspot for biodiversity, or the thousands of species—including insects, wildlife and plants—that live in the rain forest. As the Amazon continues to burn, those species are in danger, Chazdon added.

Ultimately, oxygen from the Amazon doesn’t matter all that much, scientists say. There’s plenty of oxygen in the atmosphere that has been built up over thousands of years. Even if the Amazon was completely destroyed, the supply of oxygen in the atmosphere wouldn’t be in jeopardy, Foley said. Oxygen levels are primarily regulated by long-term geological forces, such as plate tectonics, not oxygen from photosynthesis, he added.

“The Amazon is so precious and deforestation is a huge problem, for climate change, biodiversity and indigenous people living there,” Foley said. “But we can scratch one thing off the doomsday list here, we don’t have to worry about the world’s oxygen levels.”