Enter the Anthropocene : an epoch of time characterised by humans

In the first years of the 21st century Earth was being influenced by forces greater than our own and yet as vulnerable. With infinite complacency men and women went to and fro over this globe about their affairs, serene in their assurance of their empire over matter. And yet, across the vastness of time Earth viewed the actions of people with increasing despair. And slowly, but surely, she drew her plans against us….. We have borrowed these words, with some poetic licence, from H.G. Wells’ late Victorian science fiction spectacular The War of Worlds. Wells’ carefully crafted opening salvo to his novel contains words prescient in the early 21st century as we face the prospect of rapid change to our climate, and warns us about complacency in the belief of our dominion over nature. Already in the late 19th century many scientists were commenting on the extent of human influence on planet Earth. The Italian geologist Antonio Stoppani (1873) was perhaps the first to moot these ideas. Later, as the 19th century drew to a close the Swede Arrhenius and the American Chamberlain worked out the relationship between the amount of CO2 in the atmosphere and global warming. Arrhenius suggested that future generations of humans would need to raise surface temperatures to provide new areas of agricultural land and thus feed a growing population. But he could not have conceived of the massive rate of human population increase in the 20th century. In 2002 the Nobel Prize winning scientist Paul Crutzen resurrected the concept of the Anthropocene to denote the ever increasing influence of humans on Earth. The word has now entered the scientific literature as a vivid expression of the degree of environmental change on planet Earth caused by humans (Zalasiewicz et al. 2008 and references therein). For the Anthropocene to become useful though, it needs some quantification. How might an Anthropocene Epoch be unique relative to the Holocene or the Pleistocene epochs that preceded it? What criteria could we use to quantify when the Anthropocene began, and how might future generations of geologists recognise its signal in the rock record? More importantly though, does the term Anthropocene help us to understand the influence of humans on our world and how that affects the environment of the near future?