This is the final piece in a four-part series on the relationship between global climate change and mass extinction
Beneath all the scramble of detail about the relationship of global warming to species extinction, beneath all the attendant confusion of culture and money and worry, there is physics. Besides the physics of the greenhouse effect itself, which renders global warming impossible to deny, there is complex systems science and its own terrible, living clarity.
Complex systems science is the same as chaos theory, but the newer name is closer to being self-explanatory. Complex systems are processes that cannot be precisely predicted, but at the same time are deeply ordered. Traditionally, much of science has focused on simple, wholly predictable systems, like clockworks, or the orbit of planets. Complex systems work by a completely different set of rules, and so seem exotic to scientists, yet complex systems are all around us. Actually, I am a complex system, and so are you. Human thoughts, feelings, movements, and bodily changes are unpredictable, yet we can maintain the same personality, the same regular bodily functions, even almost exactly the same body temperature, for decades on end. This incredibly durable order within almost complete freedom is the heart of what makes complex systems distinct.
The biosphere, which includes the atmosphere, is a complex system as well, so understanding the basics of complex systems science is a great way to get at the underlying principles of climate change-related extinctions. With this foundation of understanding, the sometimes confusing and contradictory whirl of environmental debate and advice comes together and makes a whole. For this reason, the writer and educator, Tom Wessels developed a course entitled Principles of Sustainability, which I was lucky enough to take. He has a book out, The Myth of Progress, which covers roughly the same material, and which I recommend, but for shear clarity and punch, nothing beats the progression of charts sketched on a whiteboard, the shifting mood of student response, the gradually changing light coming in through the windows on a cold, early spring day.
The major preoccupation of the class was the flow of energy through different patterns and forms. Sunlight is energy, movement is energy, heat is energy, and the power that binds atoms together in molecules is energy. As I write, a fire leaps in our woodstove, making the metal of the stove ping and knock with heat. One way to think about this fire is as a release of stored energy. Trees, over the course of many years, collected solar energy and bound it in carbon compounds. Whatever the plants did not use for their own metabolic processes they made into wood. Now, in our stove, the sunlight that the trees turned into wood is converted into heat and light and the sound of the woodstove pinging. It is therefore sunlight that is shining out of our stove and warming the grey cat who sits by the hearth. Virtually anything can be told as a story of moving and transforming energy.
Matter can be endlessly recycled. The wood of the tree becomes ash and carbon dioxide, which will in turn become another tree. The cat by the hearth built himself from cat food and someday his matter will become other life forms. Energy, however, cannot be recycled at all. Every time energy transforms, some of it is lost, dissipating and joining the thin background radiation of the universe. Eventually, all energy dissipates. The dissipation of energy is called entropy, and philosophers and physicists debate its implications. What we know is that any system that does not have an outside source of energy will eventually sputter to a halt. Fortunately, on Earth we do have an outside energy source in the sun.
Most people have probably heard some mention of energy and entropy in a high school science class, and never really thought about them again (if they did, the premise of the Matrix trilogy would have seemed distractingly unbelievable to more people). More to the point, sustainability would not be so confusing if more people were in the habit of thinking about energy. So Tom did not just explain complex systems science and the Second Law of Thermodynamics, he tried to get us to internalize them, leading us, over and over, along paths of thought until each became habit, became our own.
One particular day, Tom delivered a lecture on the relationship of entropy to complex systems. I don’t remember whether the class included anything but a lecture that day, but Tom’s lectures are never boring. He’s not the type to put on a show, not one of those professors who use a lot of bells and whistles to grab students’ attention, but the time never drags. He drew charts, used examples, or sometimes just sat backwards in a chair in the middle of the room and talked. Most of the examples and ways of explaining I use throughout this article are actually his. If I could remember clearly enough to quote that lecture word for word I probably would.
Entropy means disorganization. Order is an energetic state, which is why houses fill up with clutter when their occupants feel lazy. This is not a metaphor; a messy room is in a more entropic state than an orderly room is. Simple systems gradually fall into disorder as they run down. Clocks lose time and eventually stop. Castles settle into ruin. Complex systems, on the other hand, actively take in energy from outside and so they can fight entropy and win. We’re self-winding clocks. Living is a constant trick of falling upstairs.
Here, Tom drew a chart, a line curving up, rapidly at first, then leveling off, then sinking down again, like one of those glacial hills that are gentle on one side and steep on the other. The line shows the developmental stages of all complex systems, rising as the system gains in size and complexity, falling as it drops into decay. The height of the line is accumulated carbon, the physical weight of the system as a whole, and it varies, left to right, along the forward march of time.
In the beginning, a system, any complex system, takes in more energy than it needs and so it grows, gaining in size, complexity, and stability. Babies need hats even when adults don’t because their body temperatures are not yet stable, but they eat and grow and soon can shed their hats. Growing forests not only get taller, they gain species and soil biomas and they begin to resist the invasion of weeds better. Their temperatures, too, become more stable, since their leaves block both wind and sun.
Eventually the energy coming in is not enough for further growth, only enough for maintenance. The child becomes an adult and the forest reaches maturity. Mature forests do not just have big trees, they also have very complex microbial communities. Mature forests smell different than younger ones. The air is quieter, and on hot days the forest remains cool. There is shelter here. There is a fluid stability, a quiet, self-maintained order.
Later comes the entropic phase. More energy is used than can be taken in and the system shrinks, destabilizes and eventually ceases to exist as a distinct entity. A forest on fire is entropic, rapidly liquidating its energy assets as its diversity and structure unravel. A field of ash and charcoal is a very simple, spent thing, entirely subject to blazing sun and freezing wind. The entropic phase is illness, dying, because when it concludes, the complex system is gone. A corpse is a very simple thing.
The biosphere as a whole goes through these same phases. In the beginning, the biosphere was very small and simple. As plants took in sunlight that energy was stored in carbon compounds and distributed to other organisms through food webs. Life spread across Earth’s surface and the products of life, coal, natural gas, and petroleum, were buried layer on layer deep in the Earth, increasing the total size of the biosphere enormously. As biosphere grew, it also grew more complex and more species evolved to take advantage of ever more specialized ecological niches.
While the biosphere as a whole is too big to be weighed, its size at any given time can be estimated by the proportion of free oxygen in the atmosphere. Without life, free oxygen is soon bound up in other molecules such as carbon dioxide. Since life builds itself out of carbon that has been stripped away from oxygen by plants, the amount of free oxygen is an indication of how much carbon is in the biosphere, the same way the size of a footprint is an indication of the size of a foot. Over hundreds of millions of years, the amount of oxygen, and therefor the size and complexity of the biosphere, grew before it finally achieved a mature stability. The births of organisms and ecosystems were now balanced against deaths and extinctions elsewhere. With minor variations, the atmosphere was stable for hundreds of millions of years, until recently.
Planetary maturity has ended.
That the planet is dying and we are killing it is not a metaphor, it is physics. The current entropic state, triggered by the liquidation of our fossil fuel energy assets, is another version of the same process an organism goes through while dying. In both cases, more energy is being used than the system is taking in, causing the system to shrink, become less stable, and become simpler. That does not mean that the biosphere cannot recover; it has had close shaves before and recovered, and will probably recover again. But the question is do we really want to be culpable for this?
That we are in a planetary entropic state explains the current mass extinction as a systemic problem. Widespread extinction is what a shrinking, simplifying biosphere looks like. Whether a species is lost to climate change directly or to habitat destruction by logging, over-hunting, or pollution, the ultimate cause is still the entropic pressure destabilizing the system as a whole.
Climate destabilization, over-use of resources, and the production of toxic industrial byproducts are all aspects of part of the biosphere—us–using more energy than the biosphere as a whole can take in. That extra energy comes from fossil fuel, the stored energy assets of the biosphere. The first-world lifestyle requires this extra energy, and all energy must come from somewhere. And as long as we insist on using more energy than the sun gives us, the biosphere will remain in an entropic state and more species will go extinct. We can save some species through various creative and heroic means, but we will not be able to change the overall fact of mass extinction as long as we continue to shrink the biosphere that supports these species. That’s physics.
We sat in stunned silence, the classroom beginning to darken in the late afternoon of a New England snowy spring. Nobody bothered to turn on a light. I, at least, felt slightly sick.
But there is still hope, because complex systems can change suddenly and completely, without warning. These bifurcation points, as they are called, are not random. They have identifiable causes, and the bifurcation points within well-studied processes, such as human embryonic development, are well known.
For example, you were once a hollow ball of cells, slowly growing bigger. Then, suddenly, you folded in on yourself and became an intricately crenulated tube and you have been an intricate tube ever since. There is no way an alien, unfamiliar with Earthly life, could have predicted you would do this. Based on all prior observation, it would have seemed reasonable to expect you to remain a ball, getting bigger and bigger like some monstrously round jellyfish, for the rest of your life. Your humanity, emerging suddenly from such simplicity, would be a complete surprise. And yet, every human being born has done it, and we all did it at exactly the same age. This paradoxical predictable unpredictability means that if you are watching a complex system go through something you’ve never seen before, there is no way to be sure what it will do. It can become something completely new on a dime.
The way it works is that complex systems are stable enough to actively resist change. The temperature of your room can drop ten, fifteen, twenty degrees, and yet your body will stay within a degree or two of 98.6 degrees Fahrenheit for as long as you have enough energy to keep shivering. The composition of Earth’s atmosphere can change radically and yet the forsythia still blooms in the spring. A ball of cells can create more and more cells and still remain a perfect ball. The system gives no sign at all of responding to the change until suddenly resistance gives way and a new order emerges. There is no way to predict, from prior conditions alone, when this shift will occur or what the new state will be. This works something like pushing on a stuck door; you push and push, and for a long time nothing seems to happen, until something gives way and the door suddenly swings open and you fall through to the other side.
These unknowable bifurcation points or tipping points are part of the danger of climate change. We can’t know when the next ounce of greenhouse gas might suddenly cause vast, horrible, and irreversible changes. But you are living proof that not all tipping points are bad. Sometimes, the thing that comes after is new and beautiful and wise.
The hopeful thing is that human societies are also complex systems. Our society as a whole may have done next to nothing about global warming so far, and obviously the hour is late, but we don’t know where the next bifurcation point is. It could be right here. If we keep pushing.
Tom, my teacher, spoke quietly into the deepening gloom;
“If you want a fight, this is a good one.”