In a paper published in the journal Quaternary International, members of the Anthropocene Working Group have suggested that the key turning point happened in the mid-20th century. From this point onward, humans did not merely leave traces of their actions, but began to alter the whole Earth system.
The changes here, once we add them up, can be staggering. The extraction of a few hundred million years worth of buried carbon, funnelled into the atmosphere as carbon dioxide, is a phenomenon of extraordinary scale and speed in Earth’s history. We already have an atmosphere like that of Pliocene times, 3m years ago – and the warmer climate and higher sea levels of that epoch look set to follow.We have doubled the amount of reactive nitrogen at the Earth’s surface – and one might have to go back billions of years to find a similar perturbation.
The biosphere is now increasingly influenced by the alien species that we have carried from continent to continent and from ocean to ocean. Such a global reshuffling has never, ever happened before in Earth’s history. We might be creating extraordinary new rock strata, in the form of our megacities.
This makeover of our planet was termed the Anthropocene some 15 years ago by the Nobel Prize-winning atmospheric chemist, Paul Crutzen. Since then, geologists have been scrambling to see whether the idea has geological reality and how it might be defined as a new geological
Slightly disturbing, worthy read: