The Carboniferous Period: How An Accident of History Made Modern Life Possible - and May Destroy It

By Dan Lennon

“The mills of the gods grind slowly, but they grind exceedingly small.”

—Greek proverb

This tale will take us back in history – all the way back to the beginning of the Earth. If you have ever looked at a chart that shows the different eons, eras, periods, and whatnot of the history of the planet, you know that they are intricately complicated. I’ve eased the task by offering this simplified version.

The box on the left represents the 4.5-billion year history of the Earth. At the bottom there is a section called “no life”. This is the billion or so years that it took life to get started. It couldn’t have been easy; after all, the Earth started as a molten ball of magma. Considering how complex even bacteria are compared to anything that isn’t alive, it is nothing short of miraculous.

After about a billion years, we find the first signs of life. It is only bacterial life, but it is life. For the next three billion years, though, that was it – just bacteria. Things seemed to have stalled. Then, a little over 500 million years ago, there is a sudden explosion of complex life. This is the big, multicellular stuff that makes up all the living things we are familiar with, including ourselves.

Now we shift to the box on the right that represents the last 500 million years. I’ll first point out the red line. This represents the Permian-Triassic extinction when 96% of all marine life and 70% of all terrestrial life died. This was very nearly the end of the big-life experiment that nature had started 250 million years before. I include this just to point out what a fragile thing life is.

Next, we turn to the Carboniferous Period, represented by the black line. This period started 360 million years ago and ended 300 million years ago. The most notable feature of this period was the huge tracts of forest that covered the globe. The first trees had begun to evolve about 40 million years earlier, but they could not grow very tall because they didn’t have lignin or cellulose, the tough fibers that make the woody trunks of trees. Trees eventually evolved lignin and cellulose and began to grow very tall – up to 160 feet or more.

The world at beginning of the Carboniferous period was a humid, tropical place. Seasons, if any, were indistinct. The Carboniferous trees and plants resembled those that live in tropical and mildly temperate areas today. They grew in wetlands and were shallow-rooted. This, combined with their great height and ponderous weight, was a bad combination, because these enormous trees would regularly become uprooted and topple into the marshy ground, landing on other trees that preceded them.

Here is where fate steps in. Although trees had evolved lignin and cellulose, no bacteria that could digest these woody substances had yet evolved. In fact, those bacteria would take another 60 million years to evolve. All this time huge trees kept growing, crashing into the swampy ground, and piling up on top of uncounted other trees, getting buried deeper and deeper into the ground. Over millions of years, subjected to the heat and pressure of deep burial, the carbon in these trees was converted into the fossil fuels we know and love today – coal, oil, and natural gas. All the fossil fuels we use were produced during this 60-million year period.

A Carboniferous Forest / From Art Station

Imagine what would have happened if the lignin-eating bacteria had not remained AWOL for so long. The trees would have begun to decay as the bacteria ate them, and there would have been no fossil fuels. Assuming that all other aspects of evolution were unchanged, when the smart ape evolved on the African savanna, he would not have been able to advance very far technologically because coal is required to make steel. Man may never have evolved much past the stage of our early civilizations if he only had wood to rely on as a source of energy.

But that was not the way things turned out. Mother Nature favored us by giving us a seemingly endless supply of fossil fuel. The fly in the ointment, of course, is that we are in the process of destroying the environment we depend upon for the preservation of our civilization and our way of life because our appetite knows no bounds. This great boon with which Mother Nature has graced us by keeping the lignin-eating bugs under wraps for 60 million years may be our undoing.

Our global society is like a man possessed, sleepwalking his way to his doom. Appeals to reason do not work because it is not reason that we lack, it is integrity – the ability to look at facts honestly even if we don’t like them, and to act on them earnestly, even if we don’t want to. We have become a willful and jaded lot, and the promise of tomorrow no longer beckons. We live for today and the devil take the hindmost.

It is sad to think of one’s own demise. It is sadder to think of the demise of one’s species. It makes all of history seem pointless. More than that, we know that life is something special, and life that is self-aware, like we are, is even more special. We know intuitively that we have only arrived here because of an impossible series of fortuitous events. We are rare and precious cargo in a vast and dark universe.

Any small change in history and we might not be here. We know, for example, that 70,000 years ago the human population was reduced to just 2,000 people. We were an endangered species. We don’t know the reason for this near-miss with extinction, but it reminds us that there is no Manifest Destiny written on the wall that promises a future for us. That is why we desperately need to start listening to the science and doing all we can do to help ourselves. It is getting late and we must hurry.