Look at images of earth from space " or from, say, the 54th floor observation deck of the Mori Tower in Tokyo at night " and the extent of the human footprint shines back. Over the last generations, evidence shows we have become the dominant species, altering " usually for the worse " the planet’s vegetation, covering swaths of the planet with megacities that swallow cropland, and harvesting the biosphere to the extent that some scientists now ask if our ravenous economies risk an ecological ”œovershoot.”

The overwhelming extent of human intervention in the planet’s processes has led some scientists to argue that our era warrants a new geological label: the Anthropocene (anthropo- for human and –cene for new). The term has not been officially recognized by geological societies and there are disputes about when it may have begun, with opinions ranging from 200 years ago, with the ushering in of the industrial age, to as far back as 8,000 years ago, when carbon emissions began to rise with the development of farming.

But the Anthropocene is an effective cultural term to describe an end to the distinction between man and nature. That blurring of lines worries many people who argue, as Alberta conservationist Harvey Locke does in this issue, that it leads to a hubristic notion that man can manage the planet. The underlying science of the damage we are doing to the biosphere that sustains us is a fact, they say, one that can’t be fixed by soothing arguments that man can fix nature.

But others see opportunities in coming to grips with humanity’s force. By embracing the concept of the Anthropocene, they argue, the earth will be what we make of it. This is where it gets interesting. It shifts the conversation from whether there are biophysical and environmental limits to human life, to one in which humans are resilient, adaptable, and capable of guiding our economy and energy use toward a system that can sustain 9”ˆbillion of us " without wrecking the earth’s life support system.

Managing our way out of trouble is, admittedly, a more hopeful outlook. Unfortunately, our generation will not be here to see who’s right. As Vaclav Smil, the distinguished scientist at the University of Manitoba, warns, we should not rush to judge whether we are in a new man-made geological era. ”œWould not it be prudent,” he asks in Harvesting the Biosphere: What We Have Taken from Nature, ”œto wait at least another 10,000 years before we make more solidly founded judgments about the adaptability and hence longevity of human civilizations?”