A New Geological Age?
By Larry Larason
The other day a friend showed me an article she had found on the internet about the Anthropocene. She had just heard about it, which is not too surprising, since the word was newly coined in 2000 to describe a new geologic epoch.
So what is the Anthropocene? First some background.
Geological ages are usually assigned following a change in flora and fauna, especially after extinction events. The Paleozoic [ancient life] Era ended 543 million years ago with the extinction of 96 percent of marine life and 70 percent of terrestrial species. That was followed by the Mesozoic Era, or age of middle life. When the dinosaurs were wiped out by an asteroid strike 65 million years ago then came the Cenozoic, new life, mammals.
The Cenozoic is subdivided into epochs. Their names and approximate beginning dates are:
Paleocene [old new], 65 million years ago
Eocene [dawn of the new], 55 mya
Oligocene [few new], 34 mya
Miocene [less new], 24 mya
Pliocene [more new], 5 mya
Pleistocene [most new], 2 mya
Holocene [entirely new], 10,000 years ago.
When you explain what the names mean they seem a little silly, don’t they? The “new” in the names could also be read as “recent.” It says something about geologists that they consider 65 million years ago to be recent. And now the Anthropocene has been proposed to continue the series of epochs. “Anthropo-” means human, as in anthropology. The world’s ecosystems are now being shaped as much by us as by nature. Anthropocene acknowledges that we are actors determining the course of nature, not just observers.
Aerial view of New York City, published in Collier’s New Encyclopedia, 1921.
Sometimes I look around my neighborhood in Gallup and try to envision it as it was before the houses were built. In scant decades the developers and contractors caused probably a million years worth of erosion when they brought in earth moving equipment to sculpt the land for streets, sidewalks, and homes. The result is not at all like what nature would have done. Some drainages were left more or less intact, but others were obliterated. Unpaved alleys have become new channels and are on the way to becoming gullies. This is just a local situation, but it happens all around the globe. Multiply our local changes by millions and you can see what that means for the planet. When I drive through parts of the Oklahoma Panhandle, I am awed as I pass by mile after mile of plowed fields. The Panhandle would be a moisture-impoverished zone, but agriculture is made possible by tapping into the Ogallala Aquifer to mine paleowater that has been stored since the ice ages. Every cultivated field is a loss of habitat for some plants and animals. Agriculture, highways, cityscapes, all limit the habitats of plants and animals. Many biologists are convinced that by the end of the century up to half of the species now living will be gone.
Humans are suspects in some of the extinctions that occurred during the Pleistocene and Holocene. Forty to fifty thousand years ago when humans first settled Australia, nineteen animals weighing more than 200 pounds disappeared, as well as three giant reptiles and a large flightless bird. North America’s large mammals – mammoths, mastodons, giant beavers – became extinct about the time humans came across the Bering land bridge. Humans arrived on Madagascar 2000 years ago and the island soon had no mammals weighing more 20 pounds. After the Maoris came to New Zealand 800 years ago all the species of moas, huge ostrich-like avians, became extinct, possibly within a single century. The reasons for these extinctions are not clear, but the coincidence of first contact with humans is suggestive. Others are more clearly our fault. I was surprised some years ago to learn that a species of parrot, the Carolina parakeet, used to live in North America. The last one died in a zoo in 1918. The birds succumbed to habitat loss, hunting, in part for food, and maybe a poultry disease imported with domesticated chickens. Another bird, the passenger pigeon, used to flock in the billions in the central US and Canada. Loss of habitat and hunting it for food made it go extinct by 1914.
While humans may have directly caused earlier extinctions by hunting a species out of existence, the ones we are causing today are more indirect. I know that some of you don’t believe that climate change is caused by humans; I’ll leave that argument for another day. There is no doubt, though, that the climate is changing. Polar ice is disappearing, and the search for the Northwest Passage around the top of Canada/Alaska, which occupied the lives of many sailors in the fifteenth and sixteenth centuries, is now over. Shipping has begun to use this route seasonally since 2009. Spring weather arrives earlier in some parts of the world, disrupting animal migration, hibernation, and breeding patterns. The ocean is becoming more acidic as it absorbs more carbon dioxide. This threatens corals and other animals that build shells of calcium carbonate. The acidic water tends to dissolve them.
While some species go extinct, others will evolve and survive. We alter the environment by the use of fertilizers, insecticides, herbicides, and other poisonous pollutants. Monsanto genetically engineered a variety of crops to be resistant to glyphosate [Roundup], but some weeds have evolved immunity to it through repeated exposure. [Does genetic engineering create new species? I’m not a biologist, so I’m not sure.] Another example of forced evolution is the Atlantic tomcod, which lives in the Hudson River. Between 1947 and 1996 two factories dumped PCBs and dioxin into the river. These chemicals are toxic in a variety of ways, but the fish evolved resistance to them. The tomcod is said to be delicious eating; however, these days they accumulate so much PCB in their flesh that consuming one might be hazardous.
We homogenize ecosystems by moving favored plants and animals around the globe. Sometimes we put livestock in places they would not willingly inhabit if they had a choice. I’m sure that most cows would prefer to live in East Texas instead of the Dinetah, but barbed wire keeps them from migrating. In other cases we move species to where they have no natural predators and they force out native creatures or overwhelm the environment. Rabbits were introduced in Australia during the mid 1800s on the whim of a sportsman for the purpose of hunting. Now they are so numerous that they are serious pests and cause extensive damage to crops. Although I rely on native plants for landscaping, I have others from all over the world growing in my yard, for example: santolina from the Mediterranean region, Russian sage from Central Asia, gazanias from southern Africa.
This is just a sampling of the issues suggesting that we have entered a new epoch. Anthropocene is still an informal designation acknowledging the significant and pervasive effect that humans have had on the world. But various geological organizations are pondering whether to make it official. Some of the questions revolve around the beginning date. The Holocene is only 10,000 years old. That’s a miniscule period of time for geology. Did the Holocene end and the Anthropocene start with the Industrial Revolution in the late 18th century? That’s when we began using fossil fuels in a big way. At least one scientist believes that the Anthropocene began with the invention of agriculture. Maybe the Holocene should be scrapped and subsumed into the care of Anthropocene.
I vote to make the Anthropocene official. Once we admit we’re living in a world so much of our own making, maybe we’ll try to take better care of it.
