Anthropocene
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The term Anthropocene is used by some scientists to describe the most recent period in the Earth's history, starting in the 18th century where the activities of the human race first began to have a significant global effect on the Earth's climate and ecosystems. The term was coined by the Nobel Prize winning scientist Paul Crutzen, who regards the influence of mankind on the Earth in recent centuries as so significant as to constitute a new geological era.
The very early anthropocene might be considered to have onset following the most recent ice age, with Homo sapiens by then dispersed across the continents, and the neolithic revolution. These brought forward agriculture and animal husbandry over hunter-gatherer subsistence, and were followed by a wave of extinctions, beginning with large mammals, and land birds, but by now having finished off or severely pressuring many others - even the biomass of vertebrate life in the oceans. Mankind became not just another runaway species enjoying an ecological release, but as a keystone species, has shaped the global ecology and environment with ever increasing disequilibrium. The environmental changes are big, and may be lasting.
One obvious geological signal of mankind's activity is increasing atmospheric carbon dioxide (CO2) content. How much of this has come about by continental deforestation or oceanic reductions in fish and release of dynamically fixed carbon from living biomass, or only by combustion of fossilized carbon in fuels is not known. Perturbation of a temperature-sensitive oceanic biochemical 'carbon sink' might also account for disequilibrium. During the glacial-interglacial cycles of the past million years, CO2 varied by approximately 100 ppm (from 180 ppm to 280 ppm). As of 2005, anthropogenic net emissions of CO2 have increased its atmospheric concentration from 280 ppm (pre-industrial "equilibrium") to more than 380 ppm.
References
- Crutzen, P. J., and E. F. Stoermer. 2000. The "Anthropocene". Global Change Newsletter. 41: 12-13.
External links
- New Scientist interview with Paul Crutzen (http://www.newscientist.com/opinion/opinterview.jsp;?id=ns24021)
- The Starving Oceans (http://www.fisherycrisis.com/)