# Worldwide fossil fuel reserves in terms of the modern biosphere... **URL:** \ **Category:** Factual Questions\ **Created:** [November 23, 2019, 10:53pm UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892 "2019-11-23T22:53:02Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [November 23, 2019, 10:53pm UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892/1 "2019-11-23T22:53:02Z")
As an order-of-magnitude estimate, worldwide coal reserves are about a trillion tonnes (from [here](https://ourworldindata.org/fossil-fuels#fossil-fuel-reserves), and oil reserves of about 2 trillion barrels (from [here.)](https://www.thebalance.com/oil-reserves-definition-categories-world-s-largest-3305873), or (2 trillion barrels/7barrels/tonne) = 285 billion tonnes of oil. You can substitue your own numbers if you prefer. I’m curious as to what multiple of the current Earth’s biosphere this represents: according to [this site](https://www.vox.com/science-and-health/2018/5/29/17386112/all-life-on-earth-chart-weight-plants-animals-pnas) there are about 500 billion tonnes of carbon in all Earth plant life and bacteria. So, naively, a trillion tonnes of coal plus 285 billion tonnes of oil = 1.25 trillion tonnes, which is maybe (?) half carbon by weight. Call it 600 billion tons of carbon. That’s roughly the same amount of carbon bound up in all Earth’s living plants and animals, right? At least for a back-of-the-envelope calculation? Or am I missing something here? How lossy would the conversion process to fossil fuels be under actual geological conditions? ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 24, 2019, 1:25pm UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892/2 "2019-11-24T13:25:33Z")
Also just to add natural gas is a very significant factor in world wide fuel reserves and should not be neglected. From very old data it looked like once were economically out of oil and coal it is very likely that liquified natural gas tankers will be going for 100’s of years longer. As far as carbon goes, natural gas is the least carbon containing fossil fuel, but it still contains carbon. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [November 24, 2019, 7:50pm UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892/3 "2019-11-24T19:50:19Z")
The total amount of kerogen (coal, oil, tar, pitch, lignite, oilshale, and innumerable tiny specks of organics) in the Earth’s crust exceeds the amount of matter in the biosphere by many orders of magnitude. Our current biosphere is only a tiny fraction of the total amount of biological material which has been buried over the last half-a-billion years. Wikipedia says that the kerogen exceeds the biosphere by 10,000 times. > **[Kerogen](https://en.wikipedia.org/wiki/Kerogen)** > > Kerogen is solid, insoluble organic matter in sedimentary rocks. It consists of a variety of organic materials, including dead plants, algae, and other microorganisms, that have been compressed and heated by geological processes. All the kerogen on earth is estimated to contain 1016 tons of carbon. This makes it the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. > The type of kerogen present in a particular rock formation ... > [@](#): > > Kerogen is solid, insoluble organic matter in sedimentary rocks. Consisting of an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter by 10,000 fold. ---
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [November 25, 2019, 12:21am UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892/4 "2019-11-25T00:21:45Z")
Ah! I had a blind spot for kerogen for some reason. Chasing that down a bit also suggests that only 0.1% of dead biomass escapes decomposition and ends up as kerogen in the first place, so that’s another factor of 1000 under normal formation conditions. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 25, 2019, 3:35am UTC](https://boards.straightdope.com/t/worldwide-fossil-fuel-reserves-in-terms-of-the-modern-biosphere/843892/5 "2019-11-25T03:35:40Z")
> [@brossa](#): > > … So, naively, a trillion tonnes of coal plus 285 billion tonnes of oil = 1.25 trillion tonnes, which is maybe (?) half carbon by weight. Call it 600 billion tons of carbon… Nitpick: “Half carbon by weight” is an under-estimate. Crude petroleum is typically 80 - 87% carbon; coal even more. Even methane ([sup]12[/sup]C[sup]1[/sup]H[sub]4[/sub]) is about 12/16 carbon.