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Does the Amazon provide 20% of our oxygen?

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Re: Does the Amazon provide 20% of our oxygen?

#141

Post by strainer »

BurningFrog wrote: post #123
strainer wrote: post #114

Earlier quoted context omitted.

The blogged claim that Amazon "consumes about as much oxygen as it produces" is not sourced and the piece seems to fly in the face of professional work on the subject. eg: "The global oxygen budget and its future projection" [1] > Fig. 4 summarizes the annual averaged global O2 budget from year 1990 to 2005, with the mass of O2 in gigatonnes (Gt) listed in each sink and for each process mentioned above (see Section 2…

Let's demystify how plants "produce oxygen". They do it by splitting CO₂ molecules. The oxygen part (O₂) goes into the air, and the carbon (C) part becomes the plant. So for the Amazon to continually produce surplus oxygen to the atmosphere, it must also continually produce an ever expanding amount of plant material ("wood") that would form an ever growing pile there. This is not happening. Because forests don't prod…

If forests did not then some other body of plant mass would have to - erosion and weathering of rocks takes a lot of oxygen out of the atmosphere, and this needs replaced by biology by photosynthesis. In the long term this is the reason the Earth needs to "breathe", and plants are how it has done so. Plants die and are eaten by ranging animals, dispersing their material, creating soils and eventually sediments. This is a long cycle through which carbon is returned to ground, sometimes to metamorphic rock.

It takes place at a lower intensity than our burning of fossil material and forests in recent history. Regrowing forest, usefully captures carbon and releases oxygen more rapidly than mature forest, but of course not rapidly enough to make up for burning them down.

Re: Does the Amazon provide 20% of our oxygen?

#142

Post by EB66 »

nearbuy wrote: post #133
EB66 wrote: post #130

Earlier quoted context omitted.

We're talking about oxygen production. Not carbon sequestration. Regarding sequestration: the carbon goes into the trunk, branches, roots and leaves of the tree. Leaves fall off the tree, rot and become soil. The tree eventually dies, rots and becomes soil. Some carbon will be given off by various decomposition processes, but the overall net effect is by far a carbon sink.

> We're talking about oxygen production. Not carbon sequestration. BurningFrog said the carbon from CO2 goes into plants. Since plant matter isn't accumulating, carbon can't be accumulating, and therefore oxygen can't either. You replied, "This is just plain wrong". So you're saying the part that is sequestered goes into the soil. That means some significant fraction of the 20 billion tonnes of carbon the Amazon phot…

> That means some significant fraction of the 20 billion tonnes of carbon the Amazon photosynthesizes each year is turning in to soil.

Correct. That fraction is obviously reduced when the forest is burned.

Re: Does the Amazon provide 20% of our oxygen?

#143

Post by wodenokoto »

wcunning wrote: post #3

The basic gist of the article is found about 1/2 way in: "First, the phytoplankton in the oceans also photosynthesise [...] Therefore in terms of TOTAL global photosynthesis, photosynthesis in the Amazon contributes around 9%. [...] Second, a bigger point that is often missed is that the Amazon consumes about as much oxygen as it produces." This reminds me, as we should all be reminded on a regular basis, the bulk of…

Consumes as much as it produces ... does that mean the animal life in the amazon consumes all the O2 produces by the plants, or does it mean that the life-cycle of any one tree consumes as much O2 when decomposing, as it produces during its time photosynthesizing?

If it is the latter, then we will see decreased oxygen levels as the forest decreases is size.

Re: Does the Amazon provide 20% of our oxygen?

#144

Post by shkkmo »

crimsonalucard wrote: post #92
DenisM wrote: post #71

A few comments are saying that forests capture a lot of CO2. But how could that be? If a forest doesn't change over thousands of years it cannot be accumulating carbon in any significant quantity. Or else where would that material go? The Amazon trees are about as tall and wide today as they were 10,000 years ago, and only so many of them fit on a given area. If the amount of vegetation remains the same the only way…

https://wwf.panda.org/knowledge_hub/where_we_work/amazon/ama... it's just less accessible but I'm pretty sure like any forest on the face of the earth, portions of dead animal and plant matter is getting sequestered into the ground while another portion is getting exhaled by animals eating the leaves or other animals eating the animals. The stuff that's getting sequestered though is probably miniscule. At the timesca…

Well, just based on the linked article:

> A final point to make is that the atmosphere is awash with oxygen, at 20.95% or 209,500 ppm (parts per million). Carbon dioxide, by comparison, is around 405 ppm and rising by around 2-3 ppm per year, over 500 times less. Human activity (around 90% of which being fossil fuel combustion) has caused this concentration to drop by around 0.005% since 1990, a trivial amount. In parallel, the same activities have caused carbon dioxide concentrations to rise by by 37 ppm since 1990, or 10%. This is a much more substantial percentage because there is so little carbon dioxide in the atmosphere to begin with, so human activities can make a major difference. This is why we need to worry about the increase of carbon dioxide in the atmosphere (and its resulting impact on climate), and why we don't need to worry about running out of oxygen.

The 3 order of magnitude difference is the relevant bit of info.

So while it takes millions of years for the amazon to have an impact on )2 levels, impacts on CO2 levels happen on the time scale of thousands of years.

This is also why it makes more sense to be concerned about the CO2 being released by burning the Amazon than the oxygen consumed by the fire.

Re: Does the Amazon provide 20% of our oxygen?

#145

Post by Merovius »

wcunning wrote: post #3

The basic gist of the article is found about 1/2 way in: "First, the phytoplankton in the oceans also photosynthesise [...] Therefore in terms of TOTAL global photosynthesis, photosynthesis in the Amazon contributes around 9%. [...] Second, a bigger point that is often missed is that the Amazon consumes about as much oxygen as it produces." This reminds me, as we should all be reminded on a regular basis, the bulk of…

> This reminds me, as we should all be reminded on a regular basis, the bulk of the things you read in the popular press are at best skimming the surface and at worst outright misleading due to grabbing onto one obscuring factoid instead of the most important pieces of information

FTR, this article is doing exactly that. Like, they a) divert your attention with the CO₂O₂ conversion (which doesn't change relative numbers in percentages of photosynthesis at all - you multiply both sides of the equation). And b) then proceeds to pretend that the Amazon eats up most of the Oxygen it produces, but the rest of the world apparently doesn't. Like, if a tree re-metabolizes 40% of the O₂ it produces, then that's also true for the 91% of O₂ produced outside the Amazon, so we still end up with the same 9% figure of all O₂ produced in the Amazon.

The article ends with the "CO₂ emission is more important". Which, again, fair. But Photosynthesis is presumably a pretty important mechanism by which CO₂ is removed from the air. So a reduction of O₂ production is equivalent to a reduction of CO₂ absorption (though you have to multiply with 2.67, don't forget!), which seems to… be a bad thing for CO₂ concentration in the air.

The gist of the article is pretty much "if you don't round and take into account maritime photosynthesis, the Amazon only produces 9% of all O₂". Which is fair. The rest is noise. It doesn't add to the argument and is just fueling the "MSM is bad!" cries…

Re: Does the Amazon provide 20% of our oxygen?

#146

Post by strainer »

shkkmo wrote: post #138
EB66 wrote: post #127

Earlier quoted context omitted.

> This is not happening. Because forests don't produce surplus oxygen. Our atmosphere doesn't work that way. This is just plain wrong. The blogger is completely wrong on this point as well. In normal atmosphere conditions, photosynthesis does result in net oxygen gain. Plants do require oxygen for respiration, but they require far less oxygen than what they produce during photosynthesis. Furthermore, at night when th…

> The blogger is completely wrong on this point as well. I think you may not have read the article closely enough: >> Plants produce oxygen through photosynthesis (green arrow). However, the the same plants consume the equivalent of over half the oxygen they produce in their own respiration ... my own team's research suggests this is more like 60% >> The remaining 40% of the Amazon oxygen budget is consumed mainly by…

> my own team's research suggests this is more like 60%

My point was he hasn't cited that research - if it is concluded ? published? reviewed?

He seems to be just having a technical rant about a contextual phrase while giving the impression that forests in general, or at least the amazon or equatorial forests do not help maintain the atmospheres oxygen content. That would certainly be a maveric proposition at this stage in Earth sciences.

Re: Does the Amazon provide 20% of our oxygen?

#147

Post by shkkmo »

m0zg wrote: post #54
sp332 wrote: post #30

Earlier quoted context omitted.

Where did you see that figure?

https://newscenter.lbl.gov/2019/08/20/amazon-rainforest-abso... Quote: "The Amazon Basin is critical to help mitigate climate change due to its trees absorbing around a quarter of the CO2 released each year from the burning of fossil fuels."

This is why you need to be careful about understanding and quoting scientific facts.

The specific quote is talking about trees in the rainforest, not the rainforest itself. The rainforest is an ecological system that also produces CO2 (mainly through microbes breaking down wood) and you can't ignore the rest of the system.

Which is not to say that the Amazon doesn't play a significant in the global environment and weather systems.

Re: Does the Amazon provide 20% of our oxygen?

#148

Post by antpls »

tcgv wrote: post #6

This subject has been treated so irresponsibly these past few days that not only people are making inaccurate statements such as "the Amazon provides 20% of our oxygen", but also high profile people such as Emmanuel Macron (France's President) and Cristiano Ronaldo (World famous soccer player) are sharing false information and photos[1] [1] http://translate.google.com/translate?hl=&sl=pt&tl=en&u=http...

Regarding the pictures, many pictures of burning forests were shared on social networks those past few days (eg. Instagram stories).

Those are images of fires to illustrate people's message, they convey the greater concept that we should be aware of the Earth as a global shared system. No one is saying 'look at this picture of the Amazon burning right now' (not even in the Macron's tweet).

Regarding "the Amazon provides 20% of our oxygen", I guess it could be debated, and the biodiversity would probably have been a better argument.

Re: Does the Amazon provide 20% of our oxygen?

#149

Post by shkkmo »

ngold wrote: post #62
wcunning wrote: post #3

The basic gist of the article is found about 1/2 way in: "First, the phytoplankton in the oceans also photosynthesise [...] Therefore in terms of TOTAL global photosynthesis, photosynthesis in the Amazon contributes around 9%. [...] Second, a bigger point that is often missed is that the Amazon consumes about as much oxygen as it produces." This reminds me, as we should all be reminded on a regular basis, the bulk of…

So yes or no does the amazon provide 20% or not?

TLDR: The amazon produces 9% and consumes 9%. We have ~500x more oxygen than CO2 so any disparities will be seen in global CO2 levels WAY before global O2 levels.

Re: Does the Amazon provide 20% of our oxygen?

#150

Post by varjag »

PeterisP wrote: post #139
atoav wrote: post #131

Earlier quoted context omitted.

Into the plant? Btw. you can easily test this yourself in a closed glas sphere.

Exactly, it goes into the plant, and is then released as the plant decomposes - so in a stable rainforest, where the total plant mass isn't increasing, the new plants growing (creating O2 and absorbing CO2) is fully balanced by old plants decomposing or burning (absorbing O2 and creating CO2); so there's no net creation of O2.

That would be true only if you always burn 100% of biomass, which doesn't happen. Carbon gets sequestered into soil, and partly consumed by insects and animals up the food chain.

All carbon in your body was once sequestered by plants.

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