What is the value of energy? An ecologist?s perspective
Paul Ziemkiewicz, PhD
When I was a student worker one of my jobs involved making agar for Utah State?s Biology Department. Agar is a gel that provides energy for microbial cultures. I poured this stuff into Petri plates and inoculated them with various fungi. The colonies grew merrily ?til the energy, nutrients, or oxygen was exhausted and then the party was over.
So here on planet Earth we live in an ecosystem that derives most of its energy from the Sun. But it wasn?t always that way. Back in the mists of time, prior to the dawn of photosynthesis about a billion years ago, the Earth received similar levels of solar radiation yet is was a pretty wretched place by our standards. The atmosphere was largely nitrogen and carbon dioxide: no oxygen. The kind of microbial life that now dominates the deeper recesses of swamp muds dominated the land back then. With no way to capture sunlight, these chemo-autotrophic microbes derived a meager living oxidizing or reducing metal ions in the waters of stagnant seas. It was a precarious existence since it was difficult for these microbes to capture carbon for their cell walls, and so digesting other organisms was an important way of making a living.
It would have stayed that way unless some enterprising mutation allowed some bacteria to synthesize chlorophyll and start capturing photons from the sun. This freed enough electrons to split the oxygen from carbon dioxide. The resulting free oxygen was a catastrophe for the existing ecosystem since oxygen was toxic to most of the species then in existence. The chemo-autotrophs were replaced by photosynthetic, or green, species which were much more efficient at capturing energy. Photosynthetic species ?soon? dominated most ecosystems. Atmospheric oxygen, driven by photosynthesis, continued to climb from zero to its present level of about 21%. The old autotrophs were driven underwater or underground away from free oxygen.
Once free carbon was readily available it could be strung together to make sugars, cellulose, and starch, not to mention proteins. The rest, so to speak, is history?but there is a moral here for us. Ecosystems, read cultures, that capture and use energy efficiently grow and prosper. Those that don?t, are replaced. There are several paths that lead to extinction. The one most germane to us is the exhaustion of our energy supply. The human population outstripped the capacity for living plants to supply its energy needs near the end of the 18th century when forests around towns and cities were exhausted. For that matter, it became impossible to haul enough forage into cities to feed all the draft animals that did much of the work. The limits of photosynthesis as the primary source of energy are evident in places like North Africa, the Middle East, China, and India. It?s hard to find a forest and much of the grasslands are grazed to dust.
Water power, coal, oil, and gas pumped energy into the industrial revolution and the mechanization of agriculture. Like a fertilized lawn, the human population grew. Malthus thought that population would outstrip food supplies but fossil fuels (stored photosynthate) provided enough energy to cause an explosion in food production. Liebig is a favorite of ecologists because he pointed out that, eventually, something in the ecosystem becomes limiting. Industrial pollution adds a new element in that accumulated toxins can become limiting on a grand scale. Much of the developed world?s environmental policy, while well intentioned, has simply driven industrialization into the developing world where it is less manageable, to put it politely.
I?ve made a point of simplifying a very complex history of the Earth?s ecosystem but reductionist theorizing is, if nothing else, easier to cram into a short essay. If we Americans have a plan, I?d suggest that we all ask ourselves what we?re trying to accomplish. Regardless of pious intentions the effect has been, since WW II, to put global population growth into overdrive. Energy growth, consumption, and production are all considered cultural values and we have earnestly exported these virtues to the rest of the world. Yet the end point is always more consumers (humans). As we replace indigenous cultures with the industrial model, one can expect per capita consumption to increase globally albeit unevenly. If our plan is to drive population growth to the point where we exhaust the things that sustain us then we don?t have much more sense than fungus in a Petri dish. If that?s the case, let?s just admit that we?re addicted to global population growth and party on till the lights go out.
If, on the other hand, we care about the future, it?s a bit disingenuous to single out energy production and consumption as a singular evil without addressing the carrying capacity of the planet. All consumption is driven by population growth. What?s the point of reducing our per capita consumption by a factor of 3 if out population increases by a factor of 4? I know it?s a touchy subject but where is it written that we can continue doubling our population every decade or so without consequences? In the natural world, organisms respond to consequences through adaptation, migration, and/or competition (war, in the extreme). When the lights go out which will we choose?
