Welcome to Terra Sapiens

1360773.  Tourists watch a meltwater waterfall on an icecap from a cruise ship.

Photo by Ralph Lee Hopkins/National Geographic

Humans have been altering Earth for millennia, but only now are we wise to what we’re doing. How will we use that wisdom?

byDavid Grinspoon is a senior scientist at the Planetary Science Institute and an adjunct professor of astrophysical and planetary science at University of Colorado. His popular writing has been featured in The New York Times, Slate, and Scientific American, among others. His latest book is Earth in Human Hands: Shaping Our Planet’s Future (2016). He lives in Washington, DC.

As a planetary astrobiologist, I am focused on the major transitions in planetary evolution and the evolving relationship between planets and life. The scientific community is converging on the idea that we have entered a new epoch of Earth history, one in which the net activity of humans has become an agent of global change as powerful as the great forces of nature that shape continents and propel the evolution of species. This concept has garnered a lot of attention, and justly so. Thinking about the new epoch – often called the Anthropocene, or the age of humanity – challenges us to look at ourselves in the mirror of deep time, measured not in centuries or even in millennia, but over millions and billions of years. And yet much of the recent discussion and debate over the Anthropocene still does not come to terms with its full meaning and importance.

Various markers have been proposed for the starting date of the Anthropocene, such as the rise in CO2, isotopes from nuclear tests, the ‘Columbian exchange’ of species between hemispheres when Europeans colonised the Americas, or more ancient human modifications of the landscape or climate. The question in play here is: when did our world gain a quality that is uniquely human? Many species have had a major influence on the globe, but they don’t each get their own planetary transition in the geologic timescale. When did humans begin changing things in a way that no other species has ever changed Earth before? Making massive changes in landscapes is not unique to us. Beavers do plenty of that, for example, when they build dams, alter streams, cut down forests and create new meadows. Even changing global climate and initiating mass extinction is not a human first. Photosynthetic bacteria did that some 2.5 billion years ago.

What distinguishes humans from other world-changing organisms must be related to our great cleverness and adaptability; the power that comes from communicating, planning and working in social groups; transmitting knowledge from one generation to the next; and applying these skills toward altering our surroundings and expanding our habitable domains. However, people have been engaged in these activities for tens of thousands of years, and have produced many different environmental modifications proposed as markers of the Anthropocene’s beginning. Therefore, those definitions strike me as incomplete. Until now, the people causing the disturbances had no way of recognising or even conceiving of a global change. Yes, humans have been altering our planet for millennia, but there is something going on now that was not happening when we started doing all that world-changing.

To me, what makes the Anthropocene unprecedented and fully worthy of the name is our growing knowledge of what we are doing to this world. Self-conscious global change is a completely new phenomenon. It puts us humans into a category all our own and is, I believe, the best criterion for the real start of the era. The Anthropocene begins when we start to realise that it has begun. This definition also provides a new angle on the long-vexing question of what differentiates our species from other life. Perhaps more than anything else, it is self-aware world-changing that marks us as something new on the planet. What are we? We are the species that can change the world and come to see what we’re doing.

By this alternative criterion, the true Anthropocene – what we might call the ‘mature Anthropocene’ – is just getting started. All of these earlier stages that have been suggested as start dates were a kind of preamble, an unconscious rather than conscious human remaking of Earth. The mature Anthropocene begins when we acquire the ability to live sustainably, and become a lasting presence on this world. This epoch arrives with mass awareness of our role in changing the planet. This is what will allow us to transition from blundering through inadvertent global changes to thoughtfully and deliberately controlling our effects on the planet. It starts with the end of our innocence.

How do we lose our innocence? By developing situational awareness: by becoming cognisant of how we are behaving on a planetary scale, in space and time, and integrating that knowledge into our actions. This will not require altruism or idealism or self-sacrifice, only accurate self-perception and enlightened self-interest. Responsible global behaviour is ultimately an act of self-preservation of, by, and for the global beast that modern technological humanity has become.

What we are observing are the effects of not only a new geologic force, but a new type of geologic force. There has never before been a geological force aware of its own actions. Humanity has at least a dim, and growing, cognisance of the effects of its presence on this planet. The possibility that we might integrate that awareness into how we interface with the Earth system is one that should give us hope. No force of nature has ever decided to change course before. If we do not like some aspects of how this epoch is playing out, its outcome is not set in stone…




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