On the cover of Our Ecological Footprint, published in 1996, a giant foot stomps on the Western hemisphere, carrying the weight of cars, overpasses and skyscrapers. William Rees, a population ecologist at the University of British Columbia, first thought of the footprint metaphor while boasting to a graduate student about the small footprint of his new computer tower in 1992. Linguists trace the use of footprint to mean space occupied to 1965 when astronomers described the landing area for a spacecraft. It would be another fourteen years before a Senate committee first uttered environmental footprint. But is this the best metaphor for humanitys impact on the natural world?

Credit: Nevit Dilmen/Wikimedia Commons

Today Our Ecological Footprint is a classic text among biologists, and ecological footprint and carbon footprint are terms as familiar as Googling and selfie. A number of NGOs offer ecological footprint calculators, including the Global Footprint Network, the WWF footprint calculator and the Earth Day Network Footprint Calculator. The calculators approximate the amount of biologically productive land required to generate the resources an individual or a population consumes and to absorb the waste that the individual or population leaves behind. The results of footprint calculators are often used to highlight global disparities. In 2007, for example, the U.S. footprint per capita was 9.0 global hectares while Chinas was just 1.8.

Global estimates of human impact on natural systems are bleak. Species are going extinct 1,000 to 10,000 times more rapidly than they historically have between major extinction events. There are as many introduced plant species on oceanic islands as native plants. Humans consume about one-third of all solar energy converted to plant matter through photosynthesis, and their actions directly impact 75 percent of terrestrial Earth or, if we take climate change into account, the entire Earth. The magnitude of these changes has prompted some geologists and ecologists to favor the term Anthropocene when referring to the present geological age, even though the International Union of Geological Sciences still places us in the Holocene.

Given the picture painted by such statistics, it is no surprise that the footprint metaphor has caught on. A footprint is a mark one never meant to leave: a revealing clue in a garden, a blemish on an otherwise sparkling floor. It evokes both the weight of whoever left it and that beings ominous absence. Verbs popular among environmentalists include trample, tread, oppress and dominate. Heavy feet imply antagonism and the lack of intimacy between humans and the non-human world. Are we waiting for the other shoe to drop?

Recently, a number of ecologists have suggested that it is no longer possible to imagine a nature where humans dont tread. Richard Hobbs and his colleagues have coined the term novel ecosystems to describe new combinations of species that arise through human action. Erle Ellis has developed maps of anthromes, areas where humans have directly altered ecological patterns and processes. Large areas of pristine wilderness no longer exist, contend the members of this new school of thought.

Anthropocene studies have polarized conservation biologists. Some, like Peter Kareiva, chief scientist for The Nature Conservancy, contend that setting aside large tracts of land is an outdated conservation strategy. Instead, conservationists need to become more people friendly and attend more seriously to working landscapes. Similarly, journalist Emma Marris argued in her 2011 book, Rambunctious Garden: Saving Nature in a Post-Wild World:

"If we fight to preserve only things that look like pristine wilderness, such as those places currently enclosed in national parks and similar refuges, our best efforts can only retard their destruction and delay the day we lose. If we fight to preserve and enhance nature as we have newly defined it, as the living background to human lives, we may be able to win. We may be able to grow nature larger than it currently is."

Other biologists believe that embracing the Anthropocene will doom biodiversity.We need to meet proponents on the battlefield, E. O. Wilson told me over dinner recently. Rather than the cheery Anthropocene, he prefers to call Earths new era of history the Eremocene: the Age of Loneliness. Elsewhere, Tim Caro and colleagues have warned that the concept of pervasive human-caused change may cultivate hopelessness and may even facilitate accelerated changes in land use motivated by profit. The controversy is one of adjectives. Scientists agree that humans have never been so populous. They agree that wilderness protection cannot be the only conservation strategy. But they disagree over whether scientists should describe humans as threats or as saviors.

Despite this new dialogue, the footprint metaphor remains a popular one. As one elementary school principal argued in The Christian Science Monitor, A footprint is a good metaphor for our individual impact on the social or natural environment. Its personal, tactile, organic, and immediately comprehensible. Its elementary. Were bipeds; we all walk and leave tracks. In a New York Times op-ed, Verlyn Klinkenborg wrote, You feel as though youre reducing global warming by saying it.

But humans have been altering the Earth for millennia, and not only for the worse. We know from the management of invasive species and fire regimes that ecosystems can benefit from human action. Some species, like the California condor, avoid extinction only through human intervention.

Credit: Steve Holmes/Flickr

So what if we move up on the human body to consider hands? A handprint, as opposed to a footprint, is deliberate, skilled and artful. It evokes human agency and the human ability to shape the world by choosing among many possible natures. A handprint suggests stewardship. Handprints allow us to ask: What is the place of creativity in conservation? How can human existence lead to good?

Importantly, handprints remind us of equity and of power. Yes, we must consume resources to live. But as those who developed the footprint metaphor have pointed out, we do not consume equally. According to the Footprint Network calculator, it would require 3.6 Earths for the entire human population to live a lifestyle similar to my own.

It is with our hands that we take from others. And it is with our hands that we give to them. It is with our hands that we plant a seedling, carry a re-usable bag and photograph a snow goose. Conservationists who characterize humans as uniformly destructive are as mistaken as those who characterize them as uniformly constructive. Both sides are missing the point that environmental governance and all the human activity that comes with it is immensely complex. Human hands speak, read, and write. They convey to us the texture of the world.