Braden Allenby is professor of civil and environmental engineering and professor of law at Arizona State University. Until 2004, he was vice president for environment, health and safety at AT&T, and is author or co-author of numerous textbooks.

The Human Earth

The Earth has become an anthropogenic planet. The dynamics of most natural systems—biological, chemical, and physical—are increasingly affected by the activities of one species, ours. The debate over how to manage global climate change; the efforts to recreate the Everglades and similar regional resource regimes to support both environmental and economic values; the effect of rapidly growing urban areas around the world on their hinterlands; the evolution of a global economy and market-oriented culture networked by information and communication systems that did not exist twenty years ago all testify to a planet whose characteristics, from the biological to the electromagnetic frequencies it radiates to space, are increasingly defined by human action. As the journal Nature put it in a 2003 editorial, "Welcome to the Anthropocene"—welcome to the Age of Humans.

This trend is not new, of course. Although this process has been accelerated by the Industrial Revolution, "natural" and human systems at all scales have in fact been affecting each other, and coevolving, for millennia, and they are now more tightly coupled than ever. Copper production during the Sung dynasty, as well as in Athens and the Roman Republic and Empire, are reflected in deposition levels in Greenland ice; and lead production in ancient Athens, Rome, and medieval Europe is reflected in increases in lead concentration in the sediments of Swedish lakes. The buildup of carbon dioxide in the atmosphere began not with the post–World War II growth in consumption of fossil fuel, but with the growth of agriculture in, and thus deforestation of, Europe, Africa, and Asia over the past millennia. Humanity's impacts on biota, both directly through predation and indirectly through the introduction of new species to indigenous habitats, has been going on for centuries as well.

What is different is that the impacts of the past were relatively minor and localized. Since the Industrial Revolution, they have become progressively more global and systematic (see "History, Responsibility, Design"). Indeed, in some areas, such as biotechnology, new fundamental technological and scientific advances have generated the potential for subsuming large chunks of previously (relatively) natural systems into human systems—in this case, genetic engineering combined with existing legal treatments of intellectual property creates the means by which the vast information store of biological genomes can be "commoditized" and made part of human economic systems (see "The Commoditization of Nature"). From a systems perspective, population and economic growth, and the evolution of ever more dense information and communication technology (ICT) infrastructures, has facilitated the linking of previously disparate local and regional patterns of human activity into globally synchronized systems, as well as ever closer coupling of human with fundamental natural systems. For the most part, we neither perceive nor recognize this state, in part perhaps because it has evolved without our conscious guidance; in part because recognition would require that we try to respond responsibly, rationally, and ethically and we do not know how to do that; and in part because the reality conflicts so basically with the popular mythology of "nature" as sacred. After all, to the extent we regard nature as something "outside the human," it becomes that much harder to recognize how much the human has actually affected the natural world.

So we should not be surprised that the language and mental models we often rely on in thinking about environmental issues have a powerful ideological and religious content, yet they are regarded by most of us as representing objectively real phenomenon. Thus, for example, terms such as "nature," "wilderness," "sustainable development," and even "environment" tend to be used as if they represented unquestionable, concrete facts and components of objective reality, but they are in fact products of a particular place, time, and culture, and have changed significantly over time. The concepts and meanings of "nature" alone make it one of the most complex of these cultural constructs. It can mean desirable; morally right; an independent source of value; the sacred; and, especially these days, the nonhuman, as "natural" ingredients are taken to mean "not made by humans" despite the fact that the products identified by such adjectives clearly are packaged, processed, and distributed in highly complex human structures. This implies that humans and their products, and especially their technologies, are somehow beyond the pale, profoundly "nonnatural."

The irony, of course, is that this implication arises at the very point in human history characterized by increasing globalization of economic, technological, and cultural patterns. This does not mean that we are entering an era of global monoculture, but, rather, increasing complexity: there are more communities, units, systems, interests, political and social entities, and technology clusters, at many different levels, and more relationships among them and natural systems at many scales than ever before. Production, consumption, economics, culture—and environmental issues—are all part of the same, increasingly complex package, and viable solutions must deal with all the varied dimensions of that package.

Dealing ethically and rationally in such a world requires a sense of realism. Environmental issues are occasionally framed in apocalyptic terms, with people speaking glibly of "saving the planet." It is highly unlikely, however, that "the world," "life," or even the existence of the human species is threatened by current levels of human activity (indeed, as regards the latter, it is well-known that generalist species, of which humans are the outstanding example, do better than others in periods of rapid change). What is threatened is the stability of global economic and social systems; especially endangered, as always, are the poor and powerless, and those who do not belong to the dominant culture. Regional and global current system states—climate and oceanic circulation systems, biological systems at all scales, elemental and hydrological cycles, and the like—are also evolving rapidly. What the dramatic language indicates is not that the planet itself is threatened, for it will certainly continue to evolve, although elements of it will follow a different path than they would in the absence of humans. Rather, it is people's judgments about the world they want, and their underlying mental models and ideologies, that are at risk: it is not the planet, but individual,...