In 1992, the science writer Andrew Revkin – in his book Global Warming: Understanding the Forecast coined the term “Anthrocene” to describe a new geological era dominated by the actions of humans.
More recently, he has quoted from his book: “We are entering an age that might someday be referred to as, say, the Anthrocene. After all, it is a geological age of our own making. The challenge now is to find a way to act that will make geologists of the future look upon this age as a remarkable time, a time in which a species began to take into account the long-term impact of its actions.” It now appears that like all respectable geological eras, the Anthrocene will be clearly identifiable as a distinct transition in the stratigraphy of the rocks that will make up that future world.
Over the past 200 years, the oceans have absorbed about half of the Carbon dioxide released into the atmosphere as a by-product of burning fossil fuels such as oil and gas. Researcher’s form the National Oceanic and Atmospheric Administration in the US have been monitoring the acidifying effect that this additional Carbon dioxide is having on the oceans, and have found a detectable decline in pH. Studies by other groups indicate that even small changes in pH have detrimental consequences on species that build their shells out of calcium carbonate, and particularly those in cold water ecosystems, which appear to be sensitive to levels of acidification that could occur in the oceans over the next few decades. These organisms; including sea urchins, cold-water corals, coralline algae, and plankton known as pteropods, provide essential food and habitat to others, their demise could affect entire ocean ecosystems.
The calcite shells of these creatures are also the raw material from which limestone rock is formed, a fact that could result in the beginning of the “Anthrocene” era made visible to future geologists as a stratigraphic boundery, formed by reduced limestone formation, and a period of mass extinction in the oceans. It seems that humans could now be changing the very bed-rock of the planet on which they live; it is a very remarkable time indeed!