We’re living in the Human Epoch, an age where humanity is profoundly affecting the Earth’s biosphere. We can’t control it – too many of us running off in all directions – but we may be able to precisely date its beginning.
Geologists divide Earth’s history into Eras: Paleozoic or Old Life, when fish, insects, and reptiles first evolved; Mesozoic or Middle Life, which saw flowering plants and the dinosaurs come and (for the non-avians) go; and Cenozoic or New Life, when mammals, including us, arose. Eras are further subdivided, especially the most recent Cenozoic, where we have more detailed knowledge.
“To pinpoint the start of [a] new phase, geologists [look] for a clear signal, described as a ‘golden spike’, that will be captured in rocks, sediments or ice – ‘a real point in time when you can show in a [geological] record when the whole Earth changed.'”
Such a record must be dramatic to be preserved in Earth’s geology, “continental movement, a big asteroid strike, or a major shift in climate,” like the end of the last Ice Age about twelve thousand years ago. That marked the start of the Holocene or Entirely New Epoch. Modern humans had already spread out of Africa, our Neanderthal cousins were gone, and we trembled on the edge of agriculture and the great ancient civilizations.
Some scientists think our Entirely New Epoch is over and the Anthropocene or Epoch of Humanity has begun. Past epochs were determined by finding a step change, a “golden spike,” in the geological record. But today we are seeing a change as it happens.
Some have suggested the 1800s and the Industrial Revolution in Europe, but I’ve run across a better proposal: 1610 AD.
Here’s the reasoning:
- Arrival of Europeans in the Americas had an “unprecedented impact on the planet…
- “The rapid global trade after that time moved species around. Maize from Central America was grown in southern Europe and Africa and China. Potatoes from South America were grown in the UK, and all the way through Europe to China. Species went the other way: wheat came to North America and sugar came to South America [and deadly diseases entered the Americas from Europe] – a real mixing of species around the world… which is a geologically unprecedented impact, setting Earth off on a new evolutionary trajectory…
- “50 million people [in the Americas] died, and most of those people were farmers… this farmland grew back to the original vegetation – tropical forest, dry forest or savannah.
- “All that growing vegetation removed enough carbon from the atmosphere to see a pronounced dip in the global atmospheric carbon dioxide concentration that can be seen in ice core records.
- “It provides an exact marker of the Anthropocene at 1610 AD, the lowest point of CO2 in the ice-core record at that time.”
So there you have it – the precise date Earth entered the Human Epoch. We don’t know what we’re doing, but we’re sure doing it big-time.