[temporaryvector]

I don't have time to read the entire article right now, but after skimming it, it seems to focus on what we might find but not on what's not there.

Focusing on Earth right now, if human civilization were to go extinct in the near future, whatever comes after us will have a much harder time getting to an industrial civilization (or maybe any civilization) because we have used up a lot of non-renewable resources that aren't ever coming back. Namely, things like abundant and easily accessible coal and oil. There's also things surface metal deposits (tin, copper, iron, etc) which are essential for making those first steps. Granted, we, as a civilization, have placed a lot of metal on the surface but it's scattered all over and I have no idea how much of it will be usable by the roach-people that come millions of years after us with no prior knowledge.

Still, all of that aside, the fact that we have coal today strikes me as a pretty convincing argument that there was no industrial civilization before us. It doesn't rule it out entirely, of course. I can imagine an industrial civilization without coal or oil, but I do have to stretch my imagination farther.

[gnomewascool]

On geological time-scales (tens of millions of years) fossil fuels will be replenished. In fact the paper presents a speculative, putative mechanism by which an industrial civilisation may inadvertently help provide these resources for future civilisations:

> [...] the prior industrial activity would have actually given rise to the potential for future industry via their own demise.

See page "148", mid-way through the second column for details. (It's a shame that Fermat's Library doesn't provide an interface for deep-linking parts of the article.)

On a time-scale of thousands of years to (probably) single-digit millions of years, you're almost certainly right, though.

[distances]

> On geological time-scales (tens of millions of years) fossil fuels will be replenished.

Will they? My understanding is that we have abundant coal thanks to the Carboniferous period, during which trees emerged but no organisms had yet adapted to break down lignin, causing massive fossilized tree deposits -- coal. As far as I see, that was an unique period in Earth's history that will not take place again.

[1] https://en.wikipedia.org/wiki/Carboniferous

[s1artibartfast]

My understanding is that the carboniferous was a particularly productive coal forming period, but in no way unique. The majority of the coal on earth has been formed since the carboniferous and the process is ongoing today.

Figure 1 in the link below provides a good demonstration of north american coal formation over time/

https://www.pnas.org/content/113/9/2442

[roenxi]

Mmm. Maybe. There is a plausible theory [0] that our coal deposits came from the era between when plants learned to produce lignin but bacteria didn't know how to break it down.

Given that lignin eating bacteria are now quite common, it is unlikely coal seams will form of the same quantity and quality.

[0] https://en.wikipedia.org/wiki/Coal#Formation

[s1artibartfast]

I Think there is some confusion between coal formation rate and coal formation volume. My understanding is that more coal has been formed since the cretaceous than during the cretaceous.

Figure 1 in the link below provides a good demonstration of north american coal formation over time.

https://www.pnas.org/content/113/9/2442

[DFHippie]

I believe it's fungus that breaks down the lignin.

[kijin]

Heaps of twisted, rusted steel on the surface is a much more efficient source of iron than iron ore in the ground. Ditto for aluminum, which is easy to handle and recycle once it has been refined (provided you can pick it out of the garbage dump) but terribly energy-intensive to extract from the ground.

Anyone who comes after us will not have much coal and oil to burn, but they'll have orders of magnitude easier access to useful metals. Imagine venturing into the half-collapsed vault of an ancient bank and finding tons of pure gold! There's a lot of fun waiting for the Indiana Jones of the next civilization.

[Gravityloss]

Or washed all the phosphorus deposits to the seas. The future is going to be interesting.

https://phys.org/news/2019-09-global-phosphorus-crisis.html

[jdsully]

I would imagine it would be much easier for the next civilization. Instead of individual mines for raw material they would set up shop over old landfills. Lots of highly refined materials there which took us thousands of years to learn how to make.

[elcomet]

There still is plenty of wood to burn, no?

[pjc50]

Wood is much less energy-dense and requires much more manual labour to process. Global steel production only took off after the switch from wood-charcoal to coke made from coal, at Coalbrookdale: https://en.wikipedia.org/wiki/Coalbrookdale

[rishav_sharan]

But wood and wood charcoal is still enough to take you past the Renaissance