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Comment by dredmorbius | Hacker News Reader

For a more complete answer on where oil does come from (spoiler: not dinosaurs --- TFA actually does a nice job of tying that myth to Sinclair Petroleum's advertising mascot), see Jeffrey S. Dukes, "Burning Buried Sunshine" (2003): https://www-legacy.dge.carnegiescience.edu/DGE/Dukes/Dukes_C... (PDF)

The beauty of this piece is that it breaks down just how much primordeal biomass goes into producing the oil (and coal and gas) we burn today, and how much ancient time is represented in each present year of consumption. (It's millions.)

I've submitted this numerous times to HN with little uptake, most recently: https://news.ycombinator.com/item?id=27827505

View on HN

Also worth to point out Earth needed millions of years to sequester that CO2 we release to atmosphere each year.

The atmospheric CO2 is not a that slow sequestering process. It has varied considerably over much shorter time periods than “millions of years”.

“Carbon dioxide concentrations have varied widely over the Earth's 4.54 billion year history.”:

https://en.m.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_...

I guess you don't understand what "sequestering" means.

Sequestering is a process where carbon becomes unavailable for biological processes.

So you have carbon circulating (present in biomass, returned to atmosphere, then back to biomass, etc.) and you have carbon that is not available for circulation.

Carbon in atmosphere is part of circulation. When a supervolcano erupts and emits a bunch of CO2, this adds carbon to atmosphere but then that carbon may very quickly be bound in biomass (for example algae, forests, etc.) This doesn't mean it is sequestered. The algae can die and ferment and forests can burn, releasing CO2 back to atmosphere.

Earth has ability to very quickly bind large amounts of CO2 from atmosphere, true.

But it does not have ability to sequester it, because as long as the carbon is present in biomass, that biomass can burn or rot and change to methane/CO2.

Current coal, oil and gas deposits are due to the fact that at early stages of evolution there was no bacteria that could process some parts of biomass. For example, plants rather than rot would just be covered with more plants and become coal deposits.

Today, it is not possible to form new coal or oil deposits, because any biomass would be quickly digested/fermented/rotted before it could be sequestered.

The pre-bacteria theory is pretty shaky fyi. There is evidence for relevant biomass-degrading bacteria being ubiquitous at the times of coal/oil formation. A more plausible theory imo is that geological conditions in the paleozoec/mesozoeic era lent themselves to greater fossil fuel formation - greater tectonic activity alone would produce the flooding and interment processes necessary to push significant volumes of biomass down to fuel the process.

For a significant mass of biomass to be pushed down it first needs to be present.

Have you ever been in a coal mine?

Coal deposits can be very thick and can consist of practically pure coal with very little anything else.

Our densest forests if suddenly "pushed" (I guess covered by ash or anything else, without loosing carbon) would be millimeters in width.

So why can't peat deposits turn into coal under the right conditions? Those form all the time under certain conditions, but they can sequester a fair amount of biomass.

AFAIU they can, but it takes a very long time, as well as depth, pressure, and temperature.

(Not my area of expertise.)

I'm unclear on how this supports a theory of pre-bacterial formation.

Yes I've been in a coal mine. What a strange stat check.

There's a fairly large amount of biomass that does get sequestered. Bogs, swamps, and tundra are particularly prone to this, and peat is effectively a low-grade coal (it played a major role in the development of Holland as well).

There is a huge amount of sequestered carbon in such landforms. I don't know how that compares with primordial carbon formations.

One factor that seems to have been significant in the formation of the coal belt that runs from the present-day Czech republic through Germany, France, northern Spain, England, and the Apallachians is that this was a region of forest and/or swampland adjacent to mountains (the Appalachians, which are literally older than dirt), with the swamps sinking rapidly into a shallow seabed. That may also have played a major role in depriving the biomass of oxygen which would permit it to rot.

My own rampant speculation: even given decomposers capable of breaking down woody plant tissue, it's possible that these were insufficiently numerous, or inefficient, or otherwise limited, in ways that aren't currently relevant, such that decomposition is more efficient and rapid today.

Interesting questions. Unlikely to be answered by any of us here soon.

The values from Dukes's paper are illuminating.

- The fossil fuels burned in a year represent about 400 years' worth of accumulated ancient biomass. That is, you'd need to capture all the biomass grown for four centuries to give the fuel we consume in one year.

- But conversion and preservation aren't perfect. So it took five million years to form just the oil we consume annually (or did in 1997, though values have remained reasonably constant since). That is, only about 0.008% of ancient biomass was stored as petroleum.

I don't know the figures for carbon-cycle sequester and release rates, though at best we're looking at centuries to remove what we've put into the atmosphere in decades, if not longer.

CO2 is mostly sequestered by reaction to form carbonates, not by reduction to biomass, but yes it will take a long time. In the intermediate it will dissolve into the deep ocean (mostly), but even that takes a while.

By chemical / geological processes, or as organic limestone (mostly shellfish / plankton skeleton) deposits?

Both? The calcium to make the limestone has to come from somewhere.

I'd consider that biological origin, if not primarily then through an obligate mechanism.

This reaction can also be accelerated by crushing basalts and other readily-available rocks to a fine sand/dust, and exposing that to the open air by spreading it over large areas of ground, such as fields or beaches. The process is not cheaper than other kinds of carbon sequestration, but it's definitely comparable and long-term sequestration of the carbon seems especially likely, since we're simply enhancing the existing geological carbon cycle.

Peridotites, in particular, with lots of olivine. Olivine weathers particularly quickly because its silicon atoms are in SiO4(4-) tetrahedra that are not covalently linked to each other (a "nesosilicate").

A problem with just spreading this out on beaches and the like is that these rocks are also often enriched in nickel vs. the average crustal rock, and this would release many millions of tonnes of nickel into the environment. There is some evidence that nickel release was part of the terrible events at the Permian-Triassic extinction. Nickel is crucial to the enzymes in the metabolic pathways leading to the production of methane in anaerobic environments. There's an idea that nickel injection into the oceans by fallout from the PT megaeruption in Siberia led to massive methane production.

So projectvesta.org (if it ever comes to pass) might actually end up inadvertently releasing methane?

I would also point out that today it is not possible to form new large scale coal/oil deposits.

Coal/oil deposits that we are using up now formed because at the time there was no bacteria that could digest dead plant/plankton matter.

This is also why all coal/oil deposits are very old. There is very little deposits after bacteria has evolved.

Nowadays there needs to be special circumstances for a piece of biological matter to not be digested by bacteria. For example it would have to be covered by permafrost or drown in oxygen-deficient lake for a very, very long time and then covered by soil.

This was the most interesting thing I learned when studying geology. More people should know about it.

It's a controversial claim and probably false, definitely don't repeat it unless you've personally verified with an expert.

Nevertheless, there are no coal or oil deposits being formed or freshly formed (in geological terms).

This roughly suggests to me, for whatever reason, there is no longer circumstances for new deposits to form.

It can also mean we are looking in the wrong places.

So at least once we send ourselves extinct through fossil-fuel driven climate change, any intelligent life that comes after us won't have the resources to do the same.

Without the easy energy source to bootstrap their tech, they may not get anywhere near having to consider that problem. They might not even make it to figuring out steel.

Interesting thought.

I think energy is least of problems. At the beginning forests provide a lot of energy and would be enough to bridge to industrial times (at least for us).

The real issue, I think, is lack of easily available raw materials like iron, tin, copper, etc. We have depended A LOT on iron practically lying on the ground.

Without having some iron easily available any startup civilization wouldn't know to look deeper and even if they wanted, they would not have any tools to do so.

At least with energy there is multiple ways to acquire it.

On the other hand there’s a lot of already processed and extracted iron and steel we’ve conveniently dug up and left around for future societies to maybe harvest.

You are right, I haven't thought of it.

I think it still works out to a net difficulty increase to any group trying to restart an industrialized civilization because of how much easy energy reserves have been permanently extracted. There’s basically no surface level coal/oil/gas that could be tapped into and finding the remaining reserves from scratch might be prohibitively difficult.

Then there’s the question of how much of the steel will still be usable when it’s time to extract it. That’s a variable problem depending on how long the ‘dark age’ is before people are rebuilding I suppose. It could be like Doctorow’s Walkaway where there’s abundant enough discarded resources you can almost achieve post-scarcity (but that world never wen through a hard crash it was more building a parallel society than a whole new one). Or it could be centuries later when a lot of the steel will be rust. Hard to say.

Most of it is exposed to weather - which means it'll oxidize and decay to uselessness rather quickly, and eventually dissolve and become diluted. With ores, we had it all in convenient form.

A lot of it yeah but large thick things like bridges will probably survive for quite a while in usable sized chunks. Copper too will be pretty available and protected in wires. It really depends on what timescale we're talking about though in the end. If we talking about humans rebooting there could still be usable bits around depending on how long it takes to begin rebuilding. If we're talking about a whole new intelligent species I agree they'll have vanishingly little to work with.

So it becomes ore again? It won't just go away.

Yes, but it will get blown by the wind and thus diluted to homeopathic concentrations.

"Ore genesis" is the term of art in geology for how various mineral ores form. Typically this involves a source, transport, and trap. Biological processes can play a major role (iron, limestone).

https://en.wikipedia.org/wiki/Ore_genesis

Useful ore deposits tend to be vast, with absoutely immense amounts (many trillions tons) of paydirt. The value of ores are that the minerals of interest are concentrated, sometimes to very high levels (50% or more of total material), though increasingly lower-grade ores (1% concentration or lower) are utilised. This means that you've got to move 99 units of mass for every unit of primary mineral extracted (overburden).

Even very large human formations are small by geological standards. The World Trade Centre towers contained about 200,000 tonnes of steel. That's a lot for humans, but a minuscule amount on a geological scale. (https://hypertextbook.com/facts/2004/EricChen.shtml)

Current iron ore extraction is on the order of about 2.5 billion tons/year. That's roughly 1/3 ton per person on Earth.

https://www.visualcapitalist.com/all-the-worlds-metals-and-m...

Vaclav Smil's Making the Modern World goes into depth on material use in contemporary civilisation:

https://www.worldcat.org/title/making-the-modern-world-mater...

(After water and oil, sand and gravel are our most-used material, then concrete and iron/steel.)

Is it possible for intelligent alien life to arise on a world without any oil/gas/coal reserves (maybe they don’t have the equivalent of plankton, or maybe they do, but bacteria that could eat the plankton evolved much earlier)? If so, would they be forever trapped on their planet, never able to go through an Industrial Age and eventually achieve rocket flight? Maybe this is one explanation for why no aliens, so far.

I’ve heard this several times, but I looked into it in more detail, and it seems that there’s some controversy: e.g. https://www.pnas.org/content/113/9/2442, https://academic.oup.com/femsre/article/41/6/941/4569254?log...

Also worth to point out Earthly life existed for millions of years with that CO2 unsequestered ;)

Is it really worth pointing this out? Why?

This is (mostly) a non-sequitur to any modern discussion about climate, the atmosphere, and its effects on human life and civilization.

Life, at this point is used to a particular equilibrium. Sure, life has existed at different equilibriums. But we also know when those equilibriums are massively disturbed (via a great oxygenation event, massive asteroid, major volcanic eruptions, etc.) much of the life dies out (obviously depends on the intensity of the disruption) and it takes many years for life to adjust to and make a new equilibrium.

Humanity should be deeply concerned with how deeply we have disrupted the equilibrium, as this disrupts the world and biosphere that sustains us.

It might be useful if you're building an argument that humanity will be better off after the current mass extinction event is over. However, I tend to find this point more often leads to a George Carlin-esque cynicism and nihilism about earth being better off without humans (or human civilization) anyways.

Thanks for the link to the previous discussion. Looking at the numbers in there, I don’t see how this conversation isn’t about overpopulation. We need such massive equivalents of land because there are too many of us, and we value living high quality lives (high standards of living with substantial consumption). The alternative is that everyone lives very constrained lives but I don’t think that is feasible or even desirable.

How do we know oil doesn't bubble up from the Earth's mantle? As far as I know, the mantle has a vast supply of carbon and water, and under the high temperatures and pressures of the mantle could form hydrocarbons that bubble up into the crust

https://news.ycombinator.com/item?id=28106291

TL;DR: coal, oil, and gas and/or the strata in which they form contain fossils and chemical signatures of ancient plant life, and are found in zones (ancient marshes/forests for coal, ancient shallow seabeds for oil) which correspond to a biotic rather than abiotic origin.

The mantle exists at depths too great for fuel formation --- the materials would be broken down at the temperatures and pressures found. Kerogenesis is depth-limited on the same basis.

it needs to be turned into a flashy webpage with lots of JS animation. pretty tough to get lots of traffic on a pdf file.

I’m on a phone and I simply can’t read it.

I can see that as a factor.

Do you not have a desktop / laptop on which you could read the article later?

I do, but I’m not going to go get it out just to read a pdf. It needs to be mobile responsive if there is a desire for people to read it on the devices they probably are usually on.

Thanks.

Just my own view, but I find that highly-recommended PDFs are often vastly more worthwhile reading than much of what is easily found in HTML format.

My preferred platform is generally an e-ink reader or tablet. At 8" or larger, they're quite good for reading most print-oriented material. My own is a 13.3" Onyx device, and I'm loving it.

They're much better for reading, and tend to reduce distractions.

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