The total value of goods and services produced by humankind in the year 1500 is estimated at $250 billion, in today’s dollars.2 Nowadays the value of a year of human production is close to $60 trillion.3 In 1500, humanity consumed about 13 trillion calories of energy per day. Today, we consume 1,500 trillion calories a day.4 (Take a second look at those figures – human population has increased fourteen-fold, production 240-fold, and energy consumption 115-fold.)
