Tuesday, January 8, 2013

Oxygen, Carbon Dioxide, Decomposition, and Renewal

A blog is a deeply personal mode of expression. Having stated this patent truth I have to say how much better I feel after a brisk walk. It's the dead of winter as I write, a nice but windy day in the 40s, too uncomfortable I think, for a bike ride. These winter days I'm stuck inside and it is real torture, as well as a frustrating damper to the work I'd like to be doing. I need oxygen!

And so, as it turns out, do most of the life forms we are acquainted with. Since the "oxygen revolution" that occurred about 3.5 billion years ago as a result of photosynthesis, multicellular organisms, animals, plants, and fungi, depend on oxygen. Our every cell is host to multiple bacteria, mitochondria, whose energy-generating mechanism requires the electron-hungry presence of oxygen in order to function. We supply the mitochondria with sugars that they break down. The mitochondria harvest electrons from the breakdown of those sugars. And they channel the movement of electrons to produce energy. Oxygen, which we also provide, sops up excess electrons and allows the mechanism to run. So in a way oxygen = energy.

Mitochondria give off carbon dioxide as part of their function, a sort of by-product of processing electrons. And carbon dioxide is where our discussion is going. It's common knowledge that excess carbon dioxide is warming our planet. The question is not if, but when we will have to cope with the consequences. Super storms, excessive drought, and record-breaking heat waves suggest that we have already begun to feel the effects of global warming. Melting glaciers and disappearing ice at the poles, both well-documented phenomena, are further evidence of global warming. The result is ever-raising sea levels. Carbon dioxide is the initiator, if not the major player in these phenomena.

But if mitochondria have been giving off carbon dioxide naturally for billions of years, what is the cause of the sudden rise in this greenhouse gas?

Plant and animal life, both present on the planet for these billions of years, have experienced a continuous cycle of decay and regeneration. Things die. And they rot. They are degraded by bacteria, fungi, and other organisms that break down their dead bodies, giving off carbon dioxide in the process. Any ecosystem is in a constant state of releasing carbon dioxide as part of its natural function, even tropical rainforests.

Some of the creatures that have died over the eons, in fact a lot of them, have ended up buried under sedimentary materials before they rotted away. Over millions and millions of years these dead organisms have been squished so hard, over such a long period of time, that they are unrecognizable today. They have turned into coal, gas, oil, and tar- the things we use as "fossil fuels."

One of the amazing things about fossil fuels is that they are composed largely (or primarily) from carbon. This is not surprising. Our bodies, once you get rid if the water, are mostly carbon. And if you think of wood, which burns nicely once it's dry, its component parts of cellulose and lignin (both highly flammable) are carbon-based.

So fossil fuels and carbon? What does this have to do with global warming? Why now?

Until the advent of the industrial revolution, most of the energy humans used was derived from their own bodies, from animals, from wood, water, and semi-fossilized deposits of peat. It wasn't until about 200 years ago that we started mining coal, which was used to heat our houses, run our large-scale industries, and create steam to move ships and trains. Still, that use of coal was limited to industrially developed societies, a relatively small segment of the earth's human population.

Internal combustion engines in cars changed that scenario in a revolutionary way. Thousands, then millions, and now billions of cars run on fossil fuel- derived oil. In the past fifty years a true explosion of carbon has entered the atmosphere thanks to the combustion (burning) of unprecedented reserves of carbon-based fuel. This explosion has been fed as well by the use of fossil fuels for generating heat, electricity, and refined fuels for air transport. What we perceive as a sort of steady-state level of consumption, a constant burning of oil, gas, and coal at the global scale, has been a reality for perhaps a human generation, barely more.

The removal and combustion of previously sequestered (buried) fossil fuels during these past few decades has resulted in an enormous rise in atmospheric carbon dioxide in levels that are new to the planet.

A small amount of that carbon dioxide is absorbed through photosynthesis in the oceans and extant forests. But the ability of these ecosystems to absorb carbon dioxide is limited by their biological capacity and by their limited ability to expand. Part of the problem of deforestation is that we are limiting that absorptive ability further.

There is no question then that when I feed my compost worms, take a walk, or even plant things in the garden, I am contributing carbon dioxide to the atmosphere. Almost all living systems give off carbon dioxide. But that level of emissions is gradual, measured, and biologically limited. The growth in carbon dioxide in our contemporary atmosphere is due to an explosion in emissions. And by definition explosions are sudden, uncontrolled, and potentially unlimited. Rather than a linear increase in carbon dioxide we are experiencing one that is exponential, and potentially out of control.


  1. Hi Sam, I was much cheered reading your blog. Here in West Wales I've just finished planting 3500 broadleaf trees this winter. Its a personal project born from a desire to 'do something' about current environmental degradation. The physicality of the planting has been hugely enjoyable despite the mud, and I've pondered over the origins of such delight to be outside in nature.
    I'm thinking that if we can understand that impetus, then perhaps we can turn others on to experience and to value the natural world. As adults we maybe tap into a bank of happy emotional childhood memories born from camping trips etc etc. So the really important thing is to get children out there, in the wild and having fun and building up that positive emotional experience. Before all their experience becomes virtual and second hand.

  2. Good good. more updates needed