When artificial light is practically free, how much of it can the world take, asks Dirk Hanson?

Like any junkie, we don’t know when we’ve had enough. “One thing that evolutionary anthropologists have learned is that humans are not necessarily natural conservationists,” says biological anthropologist Carol Worthman of Emory University, who has done field work in developing countries with scant night lighting, such as New Guinea and Vietnam. “We don’t have inbuilt mechanisms to step down consumption, even in the best interest of our own physical health.”

I love this kind of writing, which not only examines a ubiquitous but rarely thought-about aspect of our lives, but also illuminates (sorry) larger questions, in this case the problem of resource consumption. We've managed to make energy incredibly cheap, but this has not brought efficiency gains; it fact, it has just increased our appetite:

As prices fall, our use of light climbs in exact proportion. For several years now, physicist Jeff Tsao at Sandia National Laboratories has been digging into the economic cost-benefit ratios of artificial lighting. Analyzing data sets spanning three centuries and six continents, Tsao and his coworkers at Sandia have concluded that “the result of increases in luminous efficacy has been an increase in demand for energy used for lighting that nearly exactly offsets the efficiency gains—essentially a 100% rebound in energy use.” The Sandia group’s equations aren’t holy writ, but with remarkable consistency, human beings, when faced with the availability of a cheaper and more efficient lighting technology, simply use more of it. We don’t bank the savings, but instead fall into what is known as Jevons’ paradox, which states that technological improvements can be counterproductive if the resultant savings are spent rather than saved.

(H/t Dish.)