Understanding the big picture of industrial civilization - it's all about the energy
We've heard that our lifestyles are unsustainable, but what does that mean? Humans used to depend only on functioning ecosystems to survive: energy from the sun would allow plants to grow, animals would eat the plants, other animals would eat those, and so on with humans at the top of the chain. Humans, by eating plants and animals, thus lived only on the energy from the sun as it arrived. We couldn't consume much more energy than arrived from the sun and moved through ecosystems in a given year.
Modern industrial civilization, in addition to the yearly sunshine, depends heavily on coal, oil, and natural gas for energy. These fuel sources are plants and animals that died millions of years ago and were compressed inside the earth over eons. They're basically a one-time energy gift from the past - they represent energy from the sun trapped millions of years ago. Once we use it up, or use up the easy-to-get energy, we'll have to go back to using only what we get from the sun each year, like people did centuries ago.
But won't we invent alternative energy technologies to solve our problems?
Humans invent technologies that let us access energy sources, but we can't 'create' energy - we only get to use what's there already. New technologies allow us to access energy sources we couldn't reach in the past, but they don't necessarily make the energy sources feasible to use. For example, a century ago, oil fields were so rich and easy to access that we could invest the energy of 1 barrel of oil to extract 100 barrels - a 100x return on investment! Fracking has been estimated at between 2-10x return, meaning it takes the energy equivalent of 1 barrel of oil to get 2-10 barrels out, depending on the geology. This huge difference makes sense - humans, like all animals, go for the easiest-to-gather energy/food sources first, and we're now left with the dregs, and using even these energy sources up as fast as we can.
So what do we do?
We must recognize that the universe gave humanity an amazing gift - unbelievable physical resources (oil, coal, copper, etc) that let us create a civilization that allowed millions to live more comfortable lives in some ways than royalty of 500 years earlier. But those resources are running out, and we will either adapt proactively or reactively - that is, with foresight before shortages occur, or chaotically afterwards. If we act with foresight, we can choose to retain the scientific and cultural discoveries of modern civilization while learning to live without modern energy sources. I intend to do that!
