ABSTRACT
We have recently welcomed the seven-billionth person to our planet. Collectively, we use enough energy in the course of a year such that, converted to an annual rate of using power, the global consumption by all of us is twelve terawatts (TW), or 12,000,000,000 kilowatts. In comparison, a human metabolism operates at around eighty watts. A superbly trained athlete at peak condition performing at his or her optimum, might be able to produce about 500 watts. The energy used for all the interior processes inside the Earth, including the motion of portions of continents, is about 40 TW. Right now, our annual consumption of power is between a quarter to a third of all the processes inside our planet. A volcanic eruption can release about 50 TW, and an enormous earthquake even more. The 2004 earthquake in the Indian Ocean, which produced a devastating tsunami, may have released 2000 TW. However, earthquakes and volcanoes are very short-term events on our human time scale, and are a mere moment on a geological time scale. Our consumption of 12 TW goes on all the time, all day every day.
