So Tom, why isn’t coal being made anymore?

(Warning, the following story involves fossil fuels, giant insects, and fungus)

Well, I had always assumed that coal has always been made at a fairly constant slow rate in things like forests and peat bogs of the right conditions. It turns out this is not so!

Most of the world’s coal reserved were created in the Carboniferous period about 300 million years ago (the hint is in the name). This was the period when real trees first appeared and became massively successful, spreading across most of the land as a giant tropical rainforest (things were warmer and wetter back then).

BUT because trees were new and fancy, the mushrooms and bacteria hadn’t worked out how to decompose them yet! Lignin, which is the substance that bark is made of, is really difficult to digest, and trees back then were mostly bark, to defend against giant insects (think millipedes the size of crocodiles).

So all this plant matter was forming a thick, indigestible layer which was able to form massive coal beds unimpeded.

A few million years later the fungi got their enzymes into gear, and so trees that die nowadays are swiftly broken down before they can turn into coal. And then climate change led to the extinction of the world forest and the rise of dinosaurs, which is another story.

So it’s not that coal has always taken a long time to form. It’s that modern conditions prevent it easily forming!
It still DOES form, just much more rarely and slowly than when millipedes ruled the earth.