
Great Oxidation Event - hhs
https://en.wikipedia.org/wiki/Great_Oxidation_Event
======
vikramkr
Oxygen is such a beautiful double edged sword. We need it to live, but we need
complex biochemical pathways to be able to survive it. If our ancestors hadn't
evolved their way through this event we wouldn't be alive, but if the event
had never happened we wouldn't be multicellular intelligent life forms. And
now we need it to live.

~~~
rabidrat
And within a pretty tight range, too. I've heard that if O2 is more than 25%
of the atmosphere, things would catch fire spontaneously; if less than 15%,
they wouldn't be able to burn at all.

~~~
masklinn
> I've heard that if O2 is more than 25% of the atmosphere, things would catch
> fire spontaneously

Oxygen reached 35% during the Carboniferous. This lead to lifeforms taking
advantage (e.g. giant invertebrates outside the seas) as well as rainforest
wildfires as the oxygen levels significantly increased flammability of
flammable materials (most of our coal dates back to these days, where
rainforests would grow quickly, burn down to 10~20% charcoal by volume, and
that charcoal would fossilise over time).

Somewhat oddly, very few things are hypergolic with oxygen, even LOX (which is
as full of oxygen as you can get) or 100% oxygen atmosphere. Fuel will readily
ignite, but it needs an ignition source of some sort.

This is in contrast with fluorine-based oxidants like ClF3, which is
hypergolic with sand, asbestos, or water.

~~~
bonzini
... or test engineers!

~~~
lmilcin
I see what you did here, you In the Pipeline reader.

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yoble
In "Oxygen: the molecule that made the world"[1], Nick Lane also mentions the
theory that these cyanobacteria are the reason we have liquid water on earth,
while mars (for example) doesn't.

It goes like this: early earth was subjected to solar radiations which hit our
liquid water, splitting H2O into separate oxygen and hydrogen elements. The
very light hydrogen atoms (as ions, or maybe H2?) were escaping into space
while the oxygen was trapped by oxydizing rocks.

With the rise of cyanobacteria produced O2, the rocks became fully oxydized
and O2 started to build up in the air: the split hydrogen would be more likely
to recombine with atmospheric O2, keeping them on earth, and the ozone (O3)
layer started to shield the water from these radiations in the first place,
thus stopping the process and safeguarding our oceans.

[1]
[https://www.amazon.com/dp/0198607830](https://www.amazon.com/dp/0198607830)
(very cool read mixing early earth history, the rise of life, geology,
biochemistry and phylogenetics + Dr Lane is an excellent writer. Published in
2002, he has many more good updated articles about it.)

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H8crilA
Cyanobacteria is the most influential organism in the history of the planet.
Nothing comes even close (arguably including humans). Nearly all of the energy
processed in living organisms can be traced back to cyanobacteria (either via
photosynthesis, or via consuming products of photosynthesis, or products of
consuming products of ...). This extends to modern human energy usage via
fossil fuels.

~~~
GuB-42
Humans make a big deal out of 0.01% CO2, a relatively inert gas.

Cyanobacteria turned 20% of the atmosphere into very reactive O2.

I like to point that out when people say that we are destroying our planet.
Our planet will be fine with or without us, we are just hoping that it will be
with us.

~~~
carlmr
>Our planet will be fine with or without us, we are just hoping that it will
be with us.

I like that, however I think hoping and doing something about it are two
different things.

~~~
H8crilA
I think the point is: life as we know it will almost certainly outlive humans,
by a lot. We're just hoping our ride will be somewhat lengthy.

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drcode
If anyone finds this interesting, I highly recommend this lecture series:
[https://www.audible.com/pd/A-New-History-of-Life-
Audiobook/1...](https://www.audible.com/pd/A-New-History-of-Life-
Audiobook/1629976687)

It covers the great oxidation event in some detail, and covers all of the
super-early single cellular and multicellular life history in great detail.

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baq
i've lost an hour or so recently reading about a more recent event after which
there no longer were palm trees in the arctic:
[https://en.wikipedia.org/wiki/Azolla_event](https://en.wikipedia.org/wiki/Azolla_event)

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hirundo
> A chronology of oxygen accumulation suggests that free oxygen was first
> produced by prokaryotic and then later eukaryotic organisms in the ocean
> that carried out photosynthesis more efficiently, producing oxygen as a
> waste product

So oxygen is a sign of life. Can we measure oxygen's spectral line from any
exoplanets? Would enough O2 suggest our kind of life is more likely there? If
we could survey exoplanet atmospheres in our neighborhood for oxygen would
that tell us anything about the distribution of life?

~~~
marcosdumay
Oxygen spectral lines are mostly distinct from the non-life planet ones, so I
would be greatly surprised if we couldn't measure it and if astronomers didn't
do that for each planet they observed by transition.

