The pesky enzyme

There is an enzyme I need to tell you about. It was an adaptation in a class II peroxidase approximately 295 million years ago that gave rise to a specialist known as the Agaricomycetes.

This was able to do something completely new. Before it evolved there was nothing that could efficiently break down the thick cellulose walls of wood. Before this enzyme appeared a dead tree would simply fall over, degrade into tiny parts and those parts would make their way into the ground.

I learned about this enzyme a few months ago and it gave me a completely new perspective on climate change. At once I realised that the problem was both more simple and more terrifying than I had formerly thought. I think its a shame that the story of Agaricomycetes is not told more often, so I’m starting this blog by telling you about it now.

Before I begin I must warn you that I’m not a scientist, let alone the type of scientist that ought to know much about Agaricomycetes. I’m a software developer so I am working well outside of my area of knowledge. I ought to tell you though, that software developers do this all the time since their field is so restless. Sufficed to say, if anyone reading this knows a good deal more about Agaricomycetes and wishes to correct me I would love to hear from them.

When Agaricomycetes first appeared the planet Earth was very different to the one we know now. It was in fact, in a state of advanced global warming, as we describe it now. There were no ice caps at the poles and while there was plenty of life on the planet, both flora and fauna, it was unlike the life we currently recognise. It had evolved to prosper on a much hotter planet, with less land and a very different weather system.

I remember this question from Trivial Pursuit, a general knowledge board
game we used to play:

When a tree grows, where does the wood come from?

I remember stopping on this one. The obvious assumption was that the content of the wood was somehow lifted from the ground, up through the roots and along the branches, slowly adding to the whole thing piece by piece. This answer was too obvious of course, and the correct but surprising answer is the air. We were taught in school that plants ingest CO2 and release oxygen, while animals do the reverse. In this way plants and animals supply each other with the means for life.

But to imagine that a tree ingests the air around it and turns it molecule by molecule into something solid. You have to think like a scientist to buy into this.

Agaricomycetes was the first of a class known as lignin modifying enzymes (LME). They exist in fungi that feed on wood, and they also exist in the guts of animals that consume wood; including borer and some types of lice.

The time prior to the arrival of LME was known as the Carboniferous period. When this period started the planet was in something like the state we describe now when we talk about global warming. The average temperature of the planet was estimated to be 20 degrees Celsius, a good deal higher than the 12 to 14 we are looking at now. And it was not fit for humans. It did not contain the life humans are evolved for. Even if there were forms of life that existed then that might serve to feed and provide for us now, these are long gone and we can’t reproduce them any more than we could make a Stegasaurus.

As the Carboniferous period progressed, much of the carbon in the air was turned into trees, As these trees died and broke down the carbon they consisted of wound up underground. By the end of the period the global average temperature reached a new balance, around 12 degrees, and stayed that way for the nearly 300 million years. Over which time many species of plants and animals came and went.

10 million years ago the first apes appeared. Homo sapiens, humans as we know them, appeared somewhere between 1.8 and 0.2 million years ago.

The carbon that wound up underground turned into a variety of high energy forms, including peat, coal, oil and natural gas. During the industrial revolution, starting around 1760, new demand appeared for machines that provided torque, the rotational force that drove mills and vehicles and manufacture of every sort. From that time until now, we have worked like mad to remove the energy from the ground and burn it, releasing the its carbon and creating the world as we know it.

Nearly everything we do releases vast quantities of carbon in this way, from driving to work to eating a sandwich. There are very few parts of our industry that do not do this.

And, thanks to the humble Agaricomycetes, there is really no way to put it back, even if we wanted to. Truly, this is pandora’s box and it has been open for many generations now.

When you look at the growth of religions they can appear as a reaction to the world that is at once generous and indifferent. While one could expect year after year of successful crops and easy catches, sometimes, and for no reason, they could disappear and leave people to suffer. You can see why they imagined gods that were an uneasy mixture of attention and indifference. Ones that required constant appeasement.

The world science describes is not that different. Bountiful, but only within a context. There were no gods to tell us to leave the buried carbon alone, and no doubt we’d have ignored them anyway. We may have had as little as 200,000 years here. And in less than 300 we entered a creative phase that took us to space and gave us machines that can think. We’ve released carbon to do this. We’ve released more every year, observing that the more we burn, the more we make.

We’ve taken many creatures to the point of extinction along the way. And now, we appear to be taking ourselves.

What little chance we have left, how little and how late, is currently dwindling by the day. In the U.S. a man who likes to fire people says he thinks he’d be laughed at for trying. While here in New Zealand a man with a cheeky grin and a bad haircut tells everyone its a scam and not worth the bother.

New life will evolve to prosper in the climate we’ve created, and when it does the new carbon balance in the atmosphere with likely be our only legacy. Think of that: should new creatures emerge after us with the same curiosity, they may wind up trying to figure out how the planet went from 12 degrees back up to something much higher. That could be the best clue that we were here at all.

Carbon release may be the the most durable thing we achieve as a species. Think about how positive that sounds when you fail to parse it.