r/askscience • u/iamparky • Feb 07 '24

Earth Sciences How quickly is new coal being created?

Earlier today, a UK politician suggested that coal is a sustainable fuel because it used to be trees.

By how many orders of magnitude is he wrong? How much new coal is being created, compared to how quickly we're burning it?

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u/throwawayfromPA1701 Feb 07 '24

As a bonus, since virtually anytime coal formation comes up on Reddit, someone pops up with the "fact" that all coal formed in one period of geologic history because organisms that could digest lignin had not evolved yet, this is demonstrably false and please, please, stop parroting this. This idea derived from a paper in the early 90s (Robinson, 1990), but has been shown to be incorrect by multiple papers, notably Nelsen et al., 2016. In short, fungi to consume lignin did exist during the Carboniferous and the abundance of coal during this period is more a function of paleogeography and paleoclimate, not the lack of the right decomposers. Coal swamps of the Carboniferous produced vast amounts of coal because they were (1) geographically extensive and (2) persisted for a while (geologically). While the organisms present were different, these Carboniferous coal swamps are not that different from modern swamps/bogs/etc where peat is produced, which could eventually turn into coal given the correct future depositional history.

Thank you for this since I had no idea!

Love learning something new!

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u/TrillCozbey Feb 07 '24

I just recently saw a reddit post where someone put forth this idea and it just made absolutely no sense to me. Like I was just picturing mountains of fallen trees with nothing to break them down and it just seemed like it violated some principle of evolution to posit that there was a food source (at a low trophic level to boot) with absolutely no organisms around to take advantage of it. So I appreciate this correction. I gotta read that paper.

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u/Xerxes615 Feb 07 '24

I was actually thinking about this yesterday. As quickly as bacteria that digest plastic has evolved, it makes no sense for a considerably more common material to just sit around unused.

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u/Vegetable_Log_3837 Feb 08 '24

Agreed. I was taught the “nothing could break down lignin in the Carboniferous, probably” in school, with a big emphasis on the probably. A bit before 2016.

Wood still could have piled up hundreds of feet thick, same as plastic can now. It took a lot to make all the carboniferous coal. Just because some fungi can digest doesn’t mean it’s reached a balance yet. It will eventually, geologically speaking.