The funny thing is that an oxygen-rich environment is a hell-hole! Oxygen is insanely reactive and will corrode anything. Even early life on earth found oxygen toxic. It was released as a waste product by early life and they were so successful that all that oxygen accumulated resulting in the Great Oxidation Event (https://en.wikipedia.org/wiki/Great_Oxidation_Event).
That likely resulted in many species going extinct!
And the concentration into BIFs, banded iron formations, was all but certainly the result of biological activity.
Our present technology based on iron and steel owes itself to early life on Earth, from 1.6 to as much as 4 billion years ago. As with petroleum and coal-bed formation, a process unlikely to repeat in Earth's future. Iron ores are abundant, but still a finite resource.
Human civilization feels so much more fragile to me since I realized how much we owe our technological progress to the accumulated effects of biological processes over geological timescales. Fossil fuels seem like the most obvious part of this story. If we had to start over "from scratch", would it even be possible? Or have we already so thoroughly exhausted the low-hanging energy stores that a second "industrial revolution" would be effectively impossible if our present civilization collapsed deeply enough?
I wasn't aware that concentrated stores of iron are also an important part of this story!
> Or have we already so thoroughly exhausted the low-hanging energy stores that a second "industrial revolution" would be effectively impossible if our present civilization collapsed deeply enough?
There's plenty of coal left, and we will likely never exploit it, because solar is getting so cheap.
Also, despite long prophecies, peak oil never arrived either. So it doesn't look like we are running out of that stuff.
That's a loss of 2/3 of production to non-scrap effluvia on an annual basis. I'll let you work out the ultimate resource depletion cycle from that. Recycling is useful, but it's no magic bullet, and there are always losses.
The most heavily recycled metal in the US is lead, per USGS data and prior comments of mine, with recovery rates of about 75%, accounting for 40% of net production.
>That's a loss of 2/3 of production to non-scrap effluvia
Considering that the amount of stuff in our world made from steel at any one time is steadily increasing this makes sense.
>The most heavily recycled metal in the US is lead, per USGS data and prior comments of mine, with recovery rates of about 75%, accounting for 40% of net production.
There's little to no "post consumer pre-recycler" use for lead whereas every tom dick and harry can find a use for some old pipes or beams or whatever.
I once heard a similar point and it has fascinated me ever since: an alien observing human culture would be appalled at how dangerous our lives are.
Everything around us is bathed in warm oxygen, just waiting to catch fire! Our homes, our clothes, our fields, our possessions, …our hair. Ready oxidation brings vitality to Earth but it’s also ridiculously dangerous.
It might be a lot more sedate, imagine crystalline creatures from deep below the surface of an ice-ball that rely on indirect chemical gradients or geothermal.
"Your planet is how close to that star!? H20 would be liquid! How do you protect yourselves from the polar solvent leaking down into the rock?"
Conversely, a slower rate of reactivity suggests intelligent life might not yet have arisen in such environments, or ever arise before the opportunity passes.
They need a sufficiently dense energy source, sure. But it may not involve their atmosphere at all. Their plants could store solar energy in self-contained chemical batteries, and the aliens could be using those batteries to power their bodies. Instead of having to constantly breathe, they would instead need a daily battery swap.
I often like to quip that the [21%] corrosive gas is pretty nice today, and I think I'll go consume a big container of industrial solvent to help counteract the radiation from the uncontrolled nuclear [fusion] explosion in the sky.
An oxygen-rich environment is so thermodynamically unstable (it would lead to oxidation and rusting of virtually every other prevalent element) that it would be exceedingly short-lived without the presence of oxygen-liberating biological metabolism. To that extent, a high-oxygen atmosphere is one of the very clear and detectable indicators of probable life which we are capable of detecting even on extra-solar planets (via spectroscopic analysis of reflected or filtered light).
Definitely true, but oxygen is also immensely useful for life evolved to benefit from it, enabling much more complexity. I'm fascinated by the giant insects that got huge back when the oxygen level was much higher.
Related: highly recommend Robert M. Hazen Great Courses and book
That likely resulted in many species going extinct!