I guess it had to happen one day, humanity has changed the world so much that scientists have agreed that we are now living in a geological age defined by human activity. Called the Anthropocene ("Age of Humans") an international group of experts who met to consider whether we are now living in an epoch defined by humanity's impact on the planet decided 34 to zero that the Anthropocene has arrived.
The panel met to access the evidence and decide on whether they should recommend that a new geological phase has started. Their report suggests that this new age should be formally recognized and they now need to find an environmental marker that will be able to date when this new epoch began.
This date will be marked by a “Golden Spike," a line in the rock that marks when the Holocene ended and the Anthropocene begins. It's thought it will probably be some time midway in the 20th century. "Ten members of the 35-strong working group believe the best spike will probably be plutonium fallout from bomb tests in the 1950s, to be found in marine or lake sediments, ice layers or perhaps even speleothems (stalagmites and stalactites)." says the BBC. Others think plastic remains or carbon from rises in CO2 emissions could be the marker.
But whenever it began it's clear that temperature warming, sea level rise, fossil fuel ash, waste from plastics (like these rocks formed from the material), increased erosion, and radioactive particles from nuclear bombs mean that permanent change in the Earth's rock caused by humans is now very much real.
The evidence was presented at the 35th International Geological Congress in South Africa and now needs to be recognised by the International Commission on Stratigraphy (ICS) and the International Union of Geological Sciences to be made formal and recognised as part of Earth's Geological Time Scale, meaning it will then be taught in schools.
"Human impact has left discernible traces on the stratigraphic record for thousands of years – indeed, since before the beginning of the Holocene." says a statement by the Anthropocene Working Group (AWG). "However, substantial and approximately globally synchronous changes to the Earth System most clearly intensified in the ‘Great Acceleration' of the mid-20th century. The mid-20th century also coincides with the clearest and most distinctive array of signals imprinted upon recently deposited strata."
It continues, "Changes to the Earth System that characterize the potential Anthropocene Epoch include marked acceleration to rates of erosion and sedimentation, large-scale chemical perturbations to the cycles of carbon, nitrogen, phosphorus and other elements, the inception of significant change to global climate and sea level, and biotic changes such as unprecedented levels of species invasions across the Earth. Many of these changes are geologically long-lasting, and some are effectively irreversible. These and related processes have left an array of signals in recent strata, including plastic, aluminium and concrete particles, artificial radionuclides, changes to carbon and nitrogen isotope patterns, fly ash particles, and a variety of fossilizable biological remains. Many of these signals will leave a permanent record in the Earth’s strata."