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Does the Amazon provide 20% of our oxygen?

yadvindermalhi.org

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

#161

Post by mirimir »

strainer wrote: post #152
mirimir wrote: post #135

Earlier quoted context omitted.

The paper that you cite is talking about small changes. > Under the Representative Concentration Pathways (RCPs) RCP8.5 scenario, approximately 100Gt (gigatonnes) of O2 would be removed from the atmosphere per year until 2100, and the O2 concentration will decrease from its current level of 20.946% to 20.825%. 2018 209460 ppm 2100 208250 ppm That's 15 ppm per year. From Stolper et al. (2016) A Pleistocene ice core re…

So that's where he is getting the context for his rant >> "So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effectively zero." Practically, the reason why we have oxygen in the atmosphere is plant photosynthesis over long terms. We can quibble over the net annual product of every forest and ecosystem as he has - but over geological timeframe…

Sure. But long term, the Sahara may green, and "replace" the Amazon. At this point, I'd worry more about the oceans.

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

#162

Post by PeterisP »

varjag wrote: post #150
PeterisP wrote: post #139

Earlier quoted context omitted.

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.

The point is that in a stable rainforest the amount of biomass isn't growing, so you obviously do burn/decompose 100% of the newly created biomass - otherwise the amount of biomass would have grown. Carbon gets sequestered into the soil in cases where soil is being enriched and is "growing in size" (for example, when a previously barren place gets forested) but in a stable, centuries-old rainforest the soil amount really isn't increasing - so as much as gets sequestered, gets released by decomposition.

As the total biomass of insects isn't growing, the carbon they consume is balanced by the carbon released by decomposition of (otherwise) unconsumed insects; the same applies for animals up the food chain - if at the end of 2019 the total weight of insects and animals in the Amazon is not larger than at the end of 1919, then zero carbon has been sequestered in these insects and animals over a hundred years.

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

#163

Post by shkkmo »

strainer wrote: post #152
mirimir wrote: post #135

Earlier quoted context omitted.

The paper that you cite is talking about small changes. > Under the Representative Concentration Pathways (RCPs) RCP8.5 scenario, approximately 100Gt (gigatonnes) of O2 would be removed from the atmosphere per year until 2100, and the O2 concentration will decrease from its current level of 20.946% to 20.825%. 2018 209460 ppm 2100 208250 ppm That's 15 ppm per year. From Stolper et al. (2016) A Pleistocene ice core re…

So that's where he is getting the context for his rant >> "So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effectively zero." Practically, the reason why we have oxygen in the atmosphere is plant photosynthesis over long terms. We can quibble over the net annual product of every forest and ecosystem as he has - but over geological timeframe…

> over geological timeframes, the plant life they contain is the reason we have any oxygen to breath

About 1/2 of the oxygen produced is produced by Phytoplankton, which are not plants (though they are similar).

> And if the amazon currently amounts to about 20% of the plant life on earth now

The amazon accounts 16% of the photosynthesis on land.

> its not wrong to teach that it is doing 20% of the oxygen maintaining.

It is wrong. If you want to provide a nice round, reasonably accurate number you should use 10%.

> does not make a lie of the understanding and respect that forests are lungs of the planet.

Forests are important and and a significant part of the respiration of them planet, but they are less important than our oceans. Our oceans are the true lungs of the planet (edit: and they are not in great shape, atmospheric oxygen may not be an issue, but oxygenation of the ocean is more variable).

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

#164

Post by EB66 »

shkkmo wrote: post #158
EB66 wrote: post #157

Earlier quoted context omitted.

> I think you may not have read the article closely enough I did read the article closely :) >> 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 microbes breaking dow…

> The author is arguing that the Amazon rainforest is in perfect equilibrium without citing any studies or evidence The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial. >> So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effective…

> The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial.

Please go read the article again. That's exactly what he's saying. He is saying that Amazon rainforest O2 production and consumption are in equilibrium.

> The paper you cited is talking about carbon dioxide, not oxygen. The net effect on global O2 levels of carbon sequestration is minimal and not significant on human time scales. That same carbon sequestration has a significant impact on global CO2 because there is much less CO2 in the atmosphere.

For heaven's sake, please read the study. If you'd rather not read the study, then just Google until you find a satisfactory source that explains that net O2 production and net CO2 sequestration strongly correlate with one another.

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

#165

Post by dna_polymerase »

gleglegle wrote: post #102
povertyworld wrote: post #15

I haven't been following this specific news story, but I remember from my environmental sociology class that fire prevention in forests eventually leads to unnatural states that are then prone to massive uncontainable fires. Have they been suppressing natural fire in this region for too long? If this fire is naturally burning, then isn't the best response to let it run its course unless human lives are threatened?

The Amazon does not burn naturally. Fires there are man made to clear land for agriculture.

Yes it does. Especially in the dry season, although those fires usually are less severe than those caused by humans.

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

#166

Post by strainer »

mirimir wrote: post #161
strainer wrote: post #152

Earlier quoted context omitted.

So that's where he is getting the context for his rant >> "So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effectively zero." Practically, the reason why we have oxygen in the atmosphere is plant photosynthesis over long terms. We can quibble over the net annual product of every forest and ecosystem as he has - but over geological timeframe…

Sure. But long term, the Sahara may green, and "replace" the Amazon. At this point, I'd worry more about the oceans.

Burning the amazon down is something to worry about. Not afforesting widely and extracting timber from the amazon ecologically so it sequesters carbon and supplies materials replacing demand for carbon intense alternatives - is tragedy.

The advice that amazons contribution is "zero", hedged under this safety-net word "effectively" is false to the understanding of geophysics and natural history. I hope the professor will clarify his language after consideration.

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

#167

Post by pas »

zests wrote: post #43

What do you do when people quote statistics like this in real life? I usually just sit there like an insincere fool and remain quiet or offer lukewarm agreement. I can't bring myself to tell them that I disagree because I don't want to be rude but at the same time my current system is not working.

Simply share the fact you know, be prepared to explain how you know that it's reliable, what are the implications of the difference.

In my experience people listen to people who can explain things, not just claim that something is wrong/false.

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

#168

Post by pas »

jdnenej wrote: post #42
RandomBacon wrote: post #13

Earlier quoted context omitted.

But then you get the people that say, "At least they're doing something ."

Well wtf can anyone really do about a disaster on the other side of the world.

Probably incorporate their concerns when they vote. Choose representatives, leaders, groups you support (parties), that share your concern, that try to have an efficient foreign policy that cares about these things.

Naturally, this includes some marketing to support the message and to try to persuade as many people as you can.

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

#169

Post by baq »

nearbuy wrote: post #151
EB66 wrote: post #142

Earlier quoted context omitted.

> 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.

Then why is the soil layer in the Amazon only about a meter deep after millions of years of carbon sequestration? The rainforest photosynthesizes about 3 kg of carbon per square meter per year.

Bacteria and fungus eat the rest? Consider the Azolla event where dead plant material sank into very salty and oxygen poor water, which left several meters of carbon on the bottom of the polar ocean after 800k years.

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

#170

Post by shkkmo »

EB66 wrote: post #164
shkkmo wrote: post #158

Earlier quoted context omitted.

> The author is arguing that the Amazon rainforest is in perfect equilibrium without citing any studies or evidence The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial. >> So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effective…

> The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial. Please go read the article again. That's exactly what he's saying. He is saying that Amazon rainforest O2 production and consumption are in equilibrium. > The paper you cited is talking about carbon dioxide, not oxygen. The net effect on global O2 leve…

> He is saying that Amazon rainforest O2 production and consumption are in equilibrium.

where?

> net O2 production and net CO2 sequestration strongly correlate with one another.

yes, but we have ~500 times more O2 than CO2 in the atmosphere so the effects on atmospheric composition are not anywhere close to equivalent.

edit: Let me put it another way. We have so much oxygen that if we were to use any significant amount (say 1%) of that oxygen burning sequestered carbon (rainforests, oil, etc) we would have increased the carbon dioxide in the atmosphere by something like ~2000% (and would already be totally screwed in many, many ways)

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