It’s a verb, it’s an adjective, it’s… green. But what does it mean? Before you can truly get hustled you need to be off your game, out of your element, down on your luck or stuffed with a false sense of security. From the looks of things, we seem to be many of these at once. Tighten up your laces: we’re going in.

Whether attending rock shows or major sporting events, we all seem to enjoy entering the biggest, fanciest stadiums around. So, just imagine that finding new energy sources while controlling carbon emissions is the greatest challenge humanity has ever faced. There; now pull out your circle and square diagrams, bell curves and line drawings, and let’s boil the whole system down to basics.

A system is an absolute human artifact, devised primarily for the sake of scientific conversation, though a lot of this we just don’t talk about. Systems are defined by their relationships to energy and matter crossing into them, and as such there are three types of systems: open, closed and isolated. Our bodies are open systems that exist within a closed system, the earth, and we’re constantly cycling material in and out of our systems. That material is made up of elements, basically identified in the periodic table, and they comprise living things like plants and animals or non-living matter like soil, rocks and the physical environment. But there is a fixed amount of material - its overall quantity never changes.

The earth is a closed system, where energy from the sun enters. Now, this is a tremendous energy input - more energy from the sun hits the earth during one hour than every man, woman and child on it could use in a year. There’s a strong case to be made that we should actually highlight the fundamental distinction between energy sources and energy storage. The sources are rather obvious (solar, tidal, geothermal) - what we keep looking for are the ancient energy storages hidden all over the planet (pockets of fossil fuels) so as to exploit nature’s geological-timescale labor.

Sustainability for earthlings therefore, be they Pakistani or Michigander, means living within the bounds of that solar input. Simply, if you outpace that input, you’re not sustainable.

The sustainability equation is all about time. Humans have benefited from an orgasmic pace of growth fueled by stored solar energy - fossil fuels - developed over a very long period of time and used up almost completely in 100 years. We’re living, lighting, motoring, growing and mowing all on multi-million-year-old solar energy. But our epoch is an aberration. Normally, we would be forced to live within the timescale of our solar inputs; that we have in effect been able to cheat our own system has worked out quite well until lately, when we have begun to sense some limits. These limitations are real, but merely indicative of the closed system in which we live, and to the extent we ignore them our future generations are not sustainable. The supply of stored solar energy is fixed and ties us to a point of return to submitting ourselves to the timescale of energy from the sun.

Now, the very idea of limits seems un-American - an open system if there ever was one. But again, like our bodies, the USA is an open system within a larger closed system. We, too, are constantly cycling every sort of thing through and spitting it out the other end. If we look at the limits as merely fundamental constraints of a closed system with one set of inputs, maybe it begins to make more sense. In fact, maybe if we looked at our monetary system or our political system with a higher order scrutiny toward inputs, these too would begin to make more sense and we could devise more equitable, even sustainable, schemes.

And yet the energy inputs into our system are not fixed - though we have escaped their timescale for a while. But like gravity, they are pulling us back with certain ferocity. We have learned a tremendous amount about how this planet works, but it remains our challenge to concentrate the power of the sun. We must learn how to increase its direct utility - as it is now we must wait for solar inputs to work their way through the food chain. It’s a timescale issue: we’re impatient for the sun to make haste. There should be a deep discomfort in building a human civilization on an energy supply described as fossilized. But what if in the urgency to speed our technological advancement, we slowed down? There might be an inverse relationship here if we so decided.

It’s not as though we have a great deal of choice. An isolated system - the third type, with no inputs or outputs - is revealing itself in the offing with global warming trends. An isolated system generates entropy, unusable energy, to the point of death; the expanding carbon inventory in the atmosphere is succeeding at exactly what? Blocking out the sun. Approaching isolation is a function of global climate change.

Now is not the time to cower. Knowledge of the systems and laws which govern our physical world should animate the creative power of the human mind and steel our nerves. In the words of the great American horticulturist, George Washington Carver: “I believe that the great Creator has put ores and oil on this earth to give us a breathing spell. As we exhaust them, we must be prepared to fall back on our farms, which is God’s true storehouse and can never be exhausted. We can learn to synthesize material for every human need from things that grow.”

Carver knew Green as a noun, a plant you cooked with pork fat and ate. Knowledge is power and we should be quite well rested by now. Know what it has to mean when you hear something is green.