Saturday, August 24, 2019

We need to save the Amazon, but not for the sake of oxygen

Sou | 2:13 AM Go to the first of 7 comments. Add a comment
There's been a crazy meme circulating in the media about oxygen. Let's fix that.

To their credit, quite a number of media outlets have been writing about the apparent reversal of the decline in the destruction of the Amazon rainforests.

Okay, that was a mouthful. Back in past decades the Amazon rainforest was being destroyed at a phenomenal pace. Local people became concerned and eventually they were heard around the world. Finally there was an turnaround or, I should say, the rate of destruction slowed substantially. Now it's picking up again and this is a very bad thing.

The problem with many of the reports is that they include a phrase (sometimes a headline): "The Amazon is often referred to as the planet's lungs, producing 20% of the oxygen in the Earth's atmosphere". That's way wrong!

It's not just wrong, it's wrong in so many ways. First of all, the Amazon produces nothing close to 20% of the oxygen in Earth's atmosphere. What it does is contribute something close to  6% of the amount of oxygen put into the air each year from the biosphere. Not only is the number 20% quite wrong, the 6% is only the amount put into the air each year from the biosphere - that's much less than the total amount of oxygen in the air. (It's not adding to the air overall, it's an exchange. Oxygen goes in and out of the air. The oxygen in the air isn't increasing.)

Correction, perhaps: Peter Cox, who has also done research on the subject, says that a carbon stable biome does not have a net impact on O2 in the air. It's a net zero O2 exchange and just recycles the oxygen. I will have to do more research on the subject. It's not easy to find. At the plant level it's easy enough, but not at the level of individual forests or grasslands or deserts etc. [Sou - a few hours later.]

Think about it. Probably half the oxygen exchange is over land and half over ocean. The total amount of oxygen (as O2) in the air is around 1,200,000 billion tonne. That's a lot of oxygen. Around 300 billion tonne is exchanged in and out of the air each year (according to Wikipedia - I know, I don't have time to follow up original sources, but that's probably about right as long as I counted the zeros properly).

Now not only does that mean that total destruction of the rainforest would take a long time to have an effect on oxygen levels, it's likely that other plants would grow in its place (pasture for the cattle) and photosynthesis would continue.

So - be concerned, be very concerned about the destruction of the Amazon rainforest and river, but be concerned for the right reasons. Burning the forest releases CO2. Burning the forest destroys plants, wildlife, microorganisms, soil and entire ecosystems. It's a very bad thing, but you won't run out of oxygen.

I just thought I'd better put that out there. Others will do the same, and probably do a better job - but this'll do for the time being.


  1. For me, the lesson from this is the monumental stupidity of humanity. But even that only backs up the current data.

  2. I've read in several studies where the Amazon oxygen production is almost ALL consumed by the Amazon fauna. In effect, it is not "contributing" much to the rest of the planet as constantly claimed. But this distracts from the real issues of rain forest destruction, rainfall patterns, and how the Earth's weather systems are dramatically affected by the Amazon. Under Bolsanaro, rapid escalation of the Amazon has been given a green light, indigenous rights have been squashed again, and protected regions are being razed to the ground. It's like losing one of our national forests - every day. Not enough is being done (or will be done) under the political leadership, and the connedsumption habits of people all over the world. The Amazon will be reduced to a large national park eventually and the effects will be quite noticeable. ~Survival Acres~

    1. I don't know the details but AFAIK 6% is a net figure. I don't think it's been challenged in research, though I'm not sure about that.

      Rainforests have a lot of decomposing plant matter (and animal), which would use more oxygen than the animals do, but not as much as is put in the air. (Decomposition is both aerobic and anaerobic.)

      You're right about the Amazon overall - it's critically important, as are rainforests and other forests everywhere.

    2. I was wrong about that. Peter Cox agrees that the net O2 from a stable biome is zero.


  3. The proximal problem with the burning of the Amazon is the loss of biodiversity. The destruction of the Amazon would be a devastating blow to the planet's biosphere, and we're doing the same thing in tropical Asia and Africa too.

    Humanity still seems to be oblivious to how dependent we are on a functional global biosphere. It's not only the loss of potential food and medicine, but the indirect and complexly-integrated ecosystem functions that sustain us.

    Biodiverse systems like the Amazon are a proxy for the sustainability of human civilisation. If we lose it, you can be sure that we will also lose our own capacity to survive.

    1. People don't understand our dependence on food producing systems, let alone have any concept of biodiversity and natural ecosystems.

      I don't think that was always the case. It's probably related to urbanisation. Living in compounds of tar and cement with everything trucked in means one doesn't concern oneself with how the stuff on the truck got there.

      Still less does one wonder how essential are the surrounding wilderness areas. Still less that there's a direct connection between the welfare of humans and wild places they rarely if ever see.

  4. Yadvinder Malhi explains where the 20% thing comes from:


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