[seveneightn9ne]

Hm, I'd heard the Amazon consumes at least as much O2 as it produces; it's basically in equilibrium. Unfortunately I don't remember the source but it was something like Planet Earth.

I found a lot of sources quoting your 20% number, but it seems like that's not net produced O2 but rather gross.

I'd be interested if anyone can find a source that says either way about the net O2/CO2 of the Amazon.

[dahfizz]

With absolutely no expertise in the subject, I would expect any sufficiently large land area to have no net oxygen production. It's not like oxygen levels fluctuate wildly, and it seems unlikely to have such a uniform O2 level on Earth if it's coming from just a few big producers.

[usrusr]

Basic chemistry: the only ecosystems that can continually produce net O2 are those that permanently stash unoxidated C away (aka new fuel). This was the norm A Very Long Time Ago when plants were briefly ahead in the chemical arms race against everything that lives off decaying plant matter (and thus caused an imbalance which created the chemical energy we now use as fossil fuels). But in more recent history (e.g. anything dinosaur or younger) it only happens in very rare conditions. Peat-producing bog marshes are the rare exception now.

[naravara]

Plankton dying and falling to the bottom of the ocean probably sequesters something like .005% of atmospheric carbon a year. That was the main way carbon got yanked out of the atmosphere in the past. The problem is that the process is slooooooooow. Way too slow to keep up with our output.

[EGreg]

What about the other way, producing CO2?

[usrusr]

When the ecosystem is somehow tapping into an ancient stockpile of high energy C compounds to oxidate, sure, it will release more CO2 than it consumes. An example of such an ecosystem would be humans doing agriculture boosted with the Haber-Bosch process, which oxidates fossil fuel to capture plant nutrients from the air (even our crops are not entirely solar powered).

Chemistry is incredibly simple when you are only interested in the general inputs and outputs of a black box system.

[neves]

You are right, it does not produce more O2 than it consumes. Burning the forest is by far Brazil's greatest source of CO2. The forest also regulates the release of water to the atmosphere. It release as much water "transpiring" as the Amazon River estuary.

And the burning of the forest is increasing a lot in Bolsonaro's government. Well, it is increasing a lot since the president DiLma was ousted.

[tafurnace]

I believe the show "One Strange Rock" on Netflix mentioned this.