Energy

 For the first two hundred thousand years of human existence, all of the work that was done on planet earth required human muscle and brain. Paleolithic people hunted and fished. They built places to live. They made clothes. They cooked. They cared for children and elderly people. They built fires to keep warm and to cook their food, and they made sophisticated stone tools, but the energy expended on work was all their own. It came from the sun that was stored up in plants. When deer and rabbits and wooly mammoths ate the plants, they converted the energy stored in the plant matter into deer, rabbit and mammoth. When Paleolithic hunters killed and ate the plant-eating animals, they converted the same energy into their own bodies. All of the energy came from the sun.d. Even the energy released by the cooking fire had been stored up in the sticks and branches and was released in fire and warmth and grilled mastodon kabobs.

Sometime after the Neolithic Age began (12 or 15 thousand years ago), people who had hunted and killed wild animals for food began to domesticate some of them. Gradually, cattle and horses, camels and (in South America) llamas, came to share in the work of humans, carrying their loads, pulling their plows, and in general adding their muscle power to complete the work humans wanted done. Very gradually, wind mills and water wheels took some of the work that had once relied entirely on muscle, but wind and water power are good for only so much. You can grind grain with a waterwheel, or pump water with a wind mill, but plowing and hauling still took muscle power.

All the while, the earth was storing up energy. Coal, oil, and natural gas started their existences millions of years ago as sunshine. On land, plant matter fossilized into carbon-rich deposits of coal. In the shallow seas of the very ancient earth, microscopic plankton collected on the sea floor and became carbon-rich petroleum and methane, the primary ingredient in natural gas. These fossil fuels all store up the energy of sunny days of eons past. By the late Middle Ages (about six hundred years ago), coal was being mined and burned in parts of Europe where it could be found near the surface, and in the nineteenth century, coal came to be used to power steamboats on the Mississippi, steam powered ships crossing the oceans, and trains crossing the landscape virtually everywhere. In the Twentieth Century, human muscle power faded in economic importance as the age of energy transformed the planet’s landscape and climate. The carbon-rich coal, oil, and gas that had been storing up energy for millions of years was, in a matter of decades, released that energy to run cars and trucks and electric toothbrushes. As these fossil fuels burned, the complex carbon-hydrogen molecules that had been created by the actions of sunshine on plant life, gave up their stored energy in the form of heat and were broken down into simpler molecules, especially carbon dioxide (CO2). Green plants need carbon dioxide. Through the process of photosynthesis, they take up CO2 through their leaves and convert it into giant redwoods and tiny plankton and, in the process release O2—oxygen.

Carbon dioxide has an unexpected side effect. In the atmosphere, it absorbs heat from the sun. The tiny amount that has been part of the atmosphere for the last few million years has helped keep the planet warm enough to support life, but not so warm as to become, like the planet Venus, a hothouse planet, too hot for liquid water or for life to exist. However, as the CO2 trapped in fossil fuels came to be released into the atmosphere at ever faster rates since the beginning of the Industrial Revolution (in the 1750s), the small percentage of CO2 in the atmosphere has increased enough to make the planet several degrees warmer on average than it was one or two centuries ago. A few degrees warmer seems insignificant, but of course the difference between open water and a frozen lake is less than a single degree. When the atmosphere absorbs a very few additional degrees of the sun’s warmth—rather than bouncing it back into space—the glaciers begin to melt. When the glaciers melt—especially the continent size glaciers in Greenland and Antartica—the oceans become a little less salty, a little warmer, a little bigger. Cities built on the edge of the sea—New Orleans, Charleston, New York are just a few examples—begin to experience flooding on a regular basis. The beachfront moves inland. Tropical diseases unknown in the temperate zones, expand their reach.

The least developed countries contribute far less to this increase in global warming than does the industrialized world, but they suffer from its consequences far more immediately. If Africa, the Sahara Desert has been expanding into the vast grasslands that make up most of the continent at a rate of several thousand acres a year. Land that a decade ago supported herds of grazing cattle now support nothing. Herders have to move, but to where? There is no stretch of Africa inviting settlers to come and bring their lifestyles with them.

Environmental challenges of production and consumption

• fossil fuels

• alternative energy

Infrastructure challenges of production and 

consumption

• fossil fuels

• alternative energy

Locations of energy consumption (demand)

Locations of energy production (supply)

Types of energy production

• fossil fuels

• alternative energy