My takeaway: “The Amazon produces about 6 percent of the oxygen currently being made by photosynthetic organisms alive on the planet today. But surprisingly, this is not where most of our oxygen comes from. In fact, from a broader Earth-system perspective, in which the biosphere not only creates but also consumes free oxygen, the Amazon’s contribution to our planet’s unusual abundance of the stuff is more or less zero. This is not a pedantic detail. Geology provides a strange picture of how the world works that helps illuminate just how bizarre and unprecedented the ongoing human experiment on the planet really is. Contrary to almost every popular account, Earth maintains an unusual surfeit of free oxygen—an incredibly reactive gas that does not want to be in the atmosphere—largely due not to living, breathing trees, but to the existence, underground, of fossil fuels.”

Source: The Amazon Is on Fire, but Earth Has Plenty of Oxygen – The Atlantic