Energy-Capture Per-Capita Index
Discussion
"In 1971, the editors of Scientific American commissioned geo-scientist Earl Cook to try to work out how much energy we were all consuming. The best way to do this, he thought, was to work out how many calories a human consumes per day – not just in the form of food, but also in terms of the energy used to build, warm and light our homes, the energy used for industry and agriculture, and the energy used to simply get around. Over the next few years, Cook’s graph – The Flow of Energy in an Industrial Society – became a much-referenced point in energy thinking.
It was to Cook’s graph that Professor Ian Morris, of Stanford University, turned when he began to work on his own theories about the relationship between energy consumption and social development. Using the suppositions in The Flow of Energy in an Industrial Society – and aggregating the many years of work done on the subject of human energy consumption since, to confirm Cook’s basic premise – Morris published in 2010 a per-capita energy-capture index dating back to 14,000 BC, when we were still hunter gatherers. Drawing on multidisciplinary research by archaeologists, anthropologists and historians into the way humans have lived for the past 14,000 years, Morris has built up a picture of the amount of energy a single human was using then – and the amount an average human uses today.
His graph begins in 14,000 BC, when best estimates indicate that a human hunter-gatherer would be averaging between 2,000 kilocalories (kcals) and 4,000 kcals a day – or between 2 and 4.25 points, according to Morris’s system. Energy capture at this point is mostly in the form of ingested calories and shelter building. With the first great transition – to agriculture – some increase in the rate of capture is shown. But over the next few-thousand years, the increase is gradual, to say the least.
By 2000 BC, energy capture has climbed to around 17 points a day in the west and 11 in the east. As agricultural consolidation and urbanisation begins to gather pace, so does the rate of energy capture. In the year after 300BC, the rise of the Roman empire and the organisation that brought with it – combined with the weather boost of what is known as the Roman Warm Period – raises energy capture to as much as 31 points in the west and 27 in the east by 1AD. Although the rate of energy-capture increase slows down, and even declines, in the west in the next few centuries – right up until 1700 AD – it remains pretty stable (at around 30 points) in the east.
But then something remarkable begins to happen: energy-capture levels in the west begin to shoot upwards. In 1700, it stands at 32 points, about 30,000 kcals a day. By 1800, it has reached 38 points and, by 1900, it has shot up to 92. That means an average person’s kilocalorie consumption – from the food they eat, the industrial power they depend on and the means of transport they use – has risen to approximately 89,000k cals a day. By 2000, the average level of kilocalorie consumption is at an unprecedented high of 230,000kcals a day or 250 points."
(http://live-better.theguardian.com/where-does-energy-come-from-interactive)