This Earth Day, Humans Hog the Spotlight

Have we, as a species, shifted Earth’s systems so much that we can now name an entire geological epoch after ourselves? This Earth Day, Worldwatch’s Gary Gardner reflects on what it means to be Homo sapiens on a changing planet.

If you are middle-aged, as I am, your birth may be laden with deep new meaning this year. Scientists may conclude that the earth was morphing into a new geological epoch when our generation came onto the scene. In August, a subcommittee of the International Geophysical Union (IGU) will vote on whether to begin the approval process for recognition of a new “Anthropocene Epoch,” in acknowledgement of the human handprint now evident in the biological, geological, and physical systems of our planet. The import of such a vote is seismic.

Humanity’s Own Epoch? Really?

Since 2008, the IGU’s Anthropocene Working Group has been studying the question of whether human activities have altered the planet enough to warrant a new geological age to succeed the Holocene. Given that epochs typically endure for millions of years, our impulse to declare a new one after just 11,700 years of the Holocene, and after a far shorter period of human influence, smacks of the very hubris that the new epoch subtly points to. But the rapid rise of human dominance actually makes the case: what other species could render its global habitat dysfunctional in the blink of an eye?

Members of the working group have dusted for prints in their search for a human imprint on our rapidly changing planet. A subset of the group recently published in the journal  Science   with these findings of human influence:

  • Concentrations of carbon dioxide and methane began to diverge from typical Holocene patterns starting around 1850, and more markedly by 1950. The increase in average global temperature since 1900 is now diverging from typical Holocene variances of the past 1400 years. Global sea levels are rising above Late Holocene rates.
  • “Technofossils” such as concrete, plastic, and elemental aluminum are now found in new rock types around the world. Black carbon and other byproducts of fossil fuel consumption are deposited widely across the globe, especially since 1950.
  • Erosion from deforestation and road construction has altered patterns of sediment deposition. Meanwhile, dams retain sediments that would otherwise flow downstream, resulting in the subsidence of some deltas around the world.
  • Byproducts of industrial-level activities, such as polychlorinated biphenyls, pesticide residues, and lead are found at elevated levels starting in the mid-20th century.
  • Levels of nitrogen and phosphorus in soils have doubled in the past century because of chemical fertilizer use. Nitrate levels in Greenland ice samples are higher than at any time during the previous 100,000 years.
  • Extinction rates have exceeded background rates since 1500. Communities of species have been heavily reconstituted by species invasions worldwide and by changes brought about by new patterns of farming and fishing.

In January, the BBC reported that a member of the IGU working group believed that the majority of the group “now agree that we are living in an interval we should call the Anthropocene.” The designation, if adopted this summer, could be a formal declaration of a new epoch.

When did human muscle-flexing begin?

A new Anthropocene epoch could have any of several starting points, says the Science article. An “early Anthropocene” era might be detected with the adoption of agriculture, and its accompanying deforestation, several thousand years ago. Or the exchange of Old World and New World species after 1492 could be a better marker. The Industrial Revolution and its early impacts around 1800 are yet another possible starting line. And if the physical evidence from these periods is too weak, the mid-20th century, when the “Great Acceleration” of population growth and industrialization began, offers strong and abundant evidence of the human imprint on the planet. The question is whether human impact is strong enough at any of these historical moments to leave long-lasting imprints in the geological record that clearly demarcate the Holocene and the Anthropocene.

It’s a big deal

Should the blessing of the scientific community eventually come, my bet is that it will prompt a monumental shift in our self-understanding—a change in identity perhaps greater than when the first whole-Earth images arrived from space nearly a half century ago. Ironically, while a new epoch will implicitly acknowledge the vastness and range of human power, our only appropriate response is one of deep humility and atonement. Indeed, unless we respond humbly by transforming our industrial civilization, the biologists, at their next global conference, may weigh in with a re-designation of their own, stripping us of the Homo sapiens sapiens (“wise man”) moniker and proposing something more accurate.

Here at Worldwatch, we will take seriously the designation of a new epoch, should it come. Projects in the pipeline—a major initiative on education and another on new economies—are focused on solutions that allow humanity to live more humbly, showcasing not just our intelligence, but our grasp of wisdom as well. Earth Day is a good moment to ponder the challenge: if the Anthropocene is indeed our time, it is also our moment to prove ourselves worthy of the vaunted name we carry.


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