Landmark in the Earth's 4.7bn-year history as geologists hail dawn of the 'human epoch'. By Steve Connor
Biologists have their principles of evolution, physicists have their laws of thermodynamics and chemists have their periodic table. For geologists, perhaps the most hallowed reference source is the Geological Time Scale, a complex timeline depicting the entire history of the Earth as a series of distinct periods, epochs and ages, from the birth of the planet 4.7 billion years ago to the present day.
The Geological Time Scale is quite literally set in stone. As geologists dig down through the different sedimentary layers of rock, they go back in time to periods when prehistoric humans with stone tools hunted mammoths, to an earlier time 100 million years ago when dinosaurs roamed the land, and even to a distant era 3.8 billion years ago when life first arose in the ancient oceans of a more primitive world.
Changes to the Geological Time Scale resulted from natural events, whether it was the mass extinction of life from a giant asteroid impact, or an ice age resulting from changes to the orbit of the Earth around the Sun. Now, however, geologists are about to consider whether humans themselves have started to influence the geological history of the world.
They cite human-induced changes to the geology of the Earth in support of such an almost heretical position, pointing to alterations in the landscape caused by the growth of global agriculture, the mass extinction of animals and plants caused by hunting and habitat loss, differences in the composition of the atmosphere resulting from the burning of fossil fuels, and to a corresponding change to the global climate, including rising sea levels and increasing ocean acidity.
On the immense scales of geology, time is measured in tens of thousands, and indeed hundreds of millions of years. By comparison, human life and history are imperceptibly short.
So it is almost inconceivable that the Geological Time Scale should be changed to accommodate the effect that such short-lived human activity has had on the long history of the planet. Yet a significant number of scientists believes there is now a strong case to justify the modification of the Geological Time Scale to take into account the impact of humans on the Earth.
They believe that the current geological epoch, called the Holocene, which has existed since the end of the last ice age some 12,000 years ago, should now be amended. They suggest that the Geological Time Scale should be formally changed to include the start of a new phase called the Anthropocene, meaning the "human epoch".
Next month the International Commission on Stratigraphy (ICS), the body responsible for guarding the integrity of the Geological Time Scale, will meet in Prague where it will receive a preliminary report from its Anthropocene Working Group, a collection of experts charged with the task of considering the case of introducing the new, man-made sub-division. It will be the start of a long process that began in 2008 when the Stratigraphy Commission of the Geological Society of London decided that there "was merit" to the idea of formalising the term. But, ultimately, it will be for the disinguished members of the ICS to decide the matter years of heated debate.
To gauge opinion among the 50 or …