Produced energy and the pattern of human population growth from 1750. Utilization of these energy sources, together with the energy used by humans from net primary production, is now approaching the entire energy available to the global ecosystem before human intervention [Barnosky, ]. Key to colours: dark blue = coal; dark brown = oil; green = natural gas; purple = nuclear; light blue = hydro; orange brown = biomass (e.g. plants, trees). Data source from http://www.theoildrum.com/node/8936
Humans now consume between 25 and 38% of net primary production of the planet. Human modification and appropriation of NPP, and the production of energy over and above NPP, has been developing over thousands of years, but accelerated markedly from the mid-20th century onward (Figure 1).
Professor Zalasiewicz at the University of Lecister said the last times such huge effects were seen happened 2.5 billion years ago when photosynthesis appeared, and again half a billion years ago when the food web grew more complex. Although the 5 major extinction events were also huge, “ even measured against these events, human-driven changes to production and consumption are distinctly new.”
Co-author Dr Carys Bennett added: “It is without precedent to have a single species appropriating something like one quarter of the net primary biological production of the planet and to become effectively the top predator both on land and at sea.”
Some of the massive effects humans are having on the planet include mining phosphorus and fixing nitrogen to make fertilizer, burning hundreds of millions of years of fossil fuels, and directing this increased productivity that is well beyond natural levels towards animals re-engineered for our consumption.
Commentary by Alice Friedemann…