"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 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. Per Gell-Mann, I only see this in tech and science reporting, but that makes me really unreasonably suspicious of political reporting, too.
FTR, this article is doing exactly that. Like, they a) divert your attention with the CO₂<->O₂ 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…
> the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effectively zero
If this is correct, then the entire Amazon could vanish without having any effect on CO₂ levels.
But why should this be? Physics, and similar hard sciences, are deep and complex fields. There's plenty of math, jargon, and a long literature. Of course inaccurate simplifications happen when writing about it for a popular audience. Add in the weird incentives of mass media and the lack of scientific expertise among most journalists, and it makes sense that popular physics news is not so accurate.
In contrast, other newspaper topics like politics, sports, business, etc. are often literal reporting of what people do. I'm not saying any of these areas is necessarily simple, but they are at the root level about human actors, not abstract quantities that most people have 0 intuition for. So I expect that it's actually easier to do good reporting on those topics.
I was once in a local paper for my participation in a sports team. Well, my picture was. The name given to me in the article and caption was fabricated. Such a name didn't even belong to anybody else in my school, let alone on the same team!
I assume the 'reporter' was too drunk to remember my name and too embarassed to ask somebody, so he just made one up.
Like, when a journalist quotes you in print, it is often not a real direct quote, but rather the journalists interpretation of what you said (which can be way off). Always insist to "check quotes" or you could get a surprise when you read your interview.
This comment should be preserved for all time and cited in the Gell-Mann Effect entry. Do you really think physics is infinitely more complicated than finance or politics?
From discussions with my wife, who is board certified in infectious diseases, newspaper coverage of the following topics are simplified to the point of losing the main point: antimicrobial resistance, any tropical disease from malaria to Ebola, organ rejection.
I think the problem is universal not specific.
> 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 2.5). The inputs of O2 to the atmosphere by land and outgassing from oceans are quantified as 16.01 and 1.74 Gt/a, respectively. ....
[1] https://www.sciencedirect.com/science/article/pii/S209592731...
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 produce surplus oxygen. Our atmosphere doesn't work that way.
> 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
From Stolper et al. (2016) A Pleistocene ice core record of atmospheric O2 concentrations:[0]
> We present a record of Po2 reconstructed using O2/N2 ratios from ancient air trapped in ice. This record indicates that Po2 declined by 7 per mil (0.7%) over the past 800,000 years, requiring that O2 sinks were ~2% larger than sources.
That's 7000 ppm decrease over 800000 years, or 0.009 ppm per year. And so yes, atmospheric oxygen concentration is dropping lots faster now. But TFA's point that it's slow, and regulated by long-term processes, is still valid.
The blogger does professional work on the subject. The article makes it pretty clear that the net positive production of oxygen the the Amazon is so close to zero that it is only relevant on the time scale of millions of years.
First of all oxygen is constant. Oxygen is currently not the problem. And it's a good thing that it's constant because we don't want more of it either.
The problem with Amazon is that on Earth it's all interconnected and while there's plenty of room for failure, there is a tipping point, scientists have only disagreed on where that tipping point is. Once we are there however we will no longer be able to stop the chain reaction.
Especially when on fire ...
If it is the latter, then we will see decreased oxygen levels as the forest decreases is size.
If it burns,there will be leftover life that will no longer be supported by the amazon. Causing a significant increase in net Oxygen consumption.
1% uncomoemsated consumption doesn't sound like much but it will remain that way or worse whic means total O2 will continue to deplete.
Does this mean that if the Amazon rainforest fell off of the map tomorrow, life as we know it would pretty much stay the same/be ok?
It may be a click-bait factoid, but it's not like that factoid isn't an important one.
Like most of what you hear in the big press, it comes with an agenda. It's not the case that a 'zero' was mispelled or enough info was not available, thus the erroneous reporting. You won't win the argument that way. The piece simply has another purpose from the one it is claiming to have, in this case, that future generations will say that the fires wiped out the entire human civilization in all it's glory at the hand of the Brazilian president. Ergo, he has to go until it's not too late.
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 for a forest to capture carbon would be to accumulate an ever-increasing layer of it under the forest floor. That would be a lot of combustible material accumulated over millions of years that Amazon was around, and I'm pretty sure it isn't there (otherwise certain people would be mining it already).
Amazon is not scrubbing carbon out of the air, and neither does any other forest of static size. The carbon has to go into the ground to remain sequestered.
As you indicate, those people are incorrect. But a forest may contain a lot of C02, such that burning it all at once increases the amount in the atmosphere noticeably.
Soil can hold a _lot_ of carbon per square foot. Carbon that is partially lost to the atmosphere when it is plowed.
But my understanding is that tropical forests tend to have fairly carbon poor soils on the forest floor.
So a statement like “forests are scrubbing CO2 and help us against climate change” are false - a stationary size forest has no effect whatsoever.
For carbon to be sequestered it has to go into the ground and stay there.
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 timescale of our lifetime it may be negligible but I wouldn't know as I'm not an expert. Perhaps someone with the actual data can fill us in?
> 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.
[1] http://translate.google.com/translate?hl=&sl=pt&tl=en&u=http...
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.
I think it is flat out wrong and not really debatable. Also, focusing on oxygen is not the right thing to talk about because we have so much more oxygen than carbon dioxide.
Before we manage to consume significant amounts of our oxygen, we will have released so much carbon dioxide that a slight dip in O2 will not be a concern.
This is confusing for many people, I know.
Ecosystems tend to increase its complexity with time. From lava field to savanna to forests. This is how it works. Life fills the gaps.
If untouched, forests aim for the higher state of organisation possible, the so called "climax": A big forest, with huge old trees. Plants accumulate water, big plants accumulate big water, plants make water also (Is a by-product of this respiration)...
...therefore the climax is a humid forest of some kind (a rainforest, a bamboo cloudforest, a laurisilva, a scottish caledonian rainforest, a sequoia forest)
A place full of spongy fungus and plants accumulating water, a place that creates its own climate and make rains that collect in streams and then in rivers for the people benefit. They do not need fire to work at all. Wildfires are scarce and self-contained events. Such places would need a lot of energy to start burning.
The young forest is vulnerable to fire. For decades the fire risk increases. This is that people remember, but sadly they do not see the second part. After a thousand years, the risk start decreasing and then the entire area is fire-proof. Wildfires stop often when reaching an old forest.
The tragedy is that before to reach this state of full healing, the forest is burned again BY MAN (>90% of wildfires are caused by man). Is called "necessary management" or "reducing the risk", but life does not need human management. Has evolved to sustain maximum amount of life possible. We need "Management" is another way to say we want "nature explotation". Is the "groundhog day" film with trees.
Nobody is trying to restore it and return the water to Mediterranean or to California because... it would need two or three human generations to show results and it would need much smarter humans.
Does the Amazon provide 20% of our oxygen?
is equivalent to
Does the Amazon remove 20% of our waste carbon dioxide?
The main part of the "lungs" of the planet is the phytoplankton in the sea.
In my experience people listen to people who can explain things, not just claim that something is wrong/false.
Burning that carbon to CO2 requires oxygen, which will deplete the atmospheric reservoir to some degree.
If trees sequester carbon in their trunks and release oxygen, what do they use the oxygen for at night, and how come they are oxygen-neutral, do they store it somehow?
Also, if the Amazon is a carbon sink today, what about if there was dieback? It would turn into a carbon source, but how? Don’t the “unit economics” of trees remain the same?
(Notes about the oversimpliplification: Wood is made of cellulose that is a carbohydrate and sugar is algo a carbohydrate, they are quite similar chemically. Also, plants produce and "burn" other compounds.)
The red regions are largely tropical rainforest. Exceedingly highly productive, but not particularly viable for human agricultural activity.
What stands out are the regions which I'm aware are highly agriculturally productive, indicated in green and cyan: the eastern half of the US, generally, the Argentine and Brazillian Pampas regions, the Sahel, Europe (particularly western Europe -- England, France, and Germany), and south and East Asia. A small patch of Central America.
Notably contrasting: the western US, other than a thin strip (the central valleys of California and Oregon), the Australia, other than the extreme south-eastern band, the Sahara, virtually all of Russia, western South America, and most of Canada. And of course, the Sahara and Antarctica.
We're feeding 7.7 billions of souls on those regions of green and light blue. Those are also the regions in which the great civilisations of the past have developed -- compare with a time-lapse of human population such as:
Anyway, the geological history of oxygen is pretty wild:
To increase net oxygen levels in the atmosphere and reduce CO2 levels we would also have to eliminate a lot of the microorganisms that help recycle dead trees and go back to the Paleozoic era and before when these organisms didn't exist and the Earth witnessed several glaciation events.
Adding more stable forests to the world does not reduce CO2 levels or increase oxygen levels (relative to after it becomes a stable forest). It just speeds up the carbon cycle.
“The lungs of the world” is a poetic phrase. Trying to make it literal diminishes it, by giving cynics a small thread to pull on until it unravels — while in the process ignoring all the other ways in which the Amazon is important.
A vibrant discussion of the original post would be relevant — using the misaccounting as a cudgel against environmentalists and journalism as a whole is explicitly not the spirit of HN.
Though i have to admit to bring skeptical of his analysis that suggests the rainforest is a net zero on oxygen production.
But the article totally misses the issue of carbon capture.
