Sharing the Garden
Environmental problems, from the extinction of species to climate change and pollution, are all symptoms of a larger syndrome. One way to understand this syndrome is to think about how much of the Earth's biological productivity is appropriated by humans. Using energy from the sun and carbon dioxide from the air, plants make complex sugars, which are the basic currency of life on Earth. Photosynthetically fixed carbon in the form of sugars is called primary production because, with the exception of some bacteria living in deep sea vents, it is the basic foodstuff for every other form of life on Earth.
In 1986 Vitousek et al estimated that humans appropriate about 40 percent of the world's net primary production1. Rojstaczer et al revisited this topic recently and came up with essentially the same number2.
People take 40 percent off the top of all that nature provides. What does this enormous tax on nature do to the natural world and ecosystem function? What constraints does it impose on our social development as our population grows and becomes more affluent?
We discussed these issues with Christopher Field of the Carnegie Institution of Washington at Stanford.