Humans are an environmental force that impacts Earth’s ecosystems.

When it comes to the environment, modern societies are not as different from the Vikings as one might assume. Vikings chose livestock and farming methods that were ill suited to Greenland’s climate and natural environment. We, too, use farming practices that strip away topsoil and diminish the land’s fertility. We have overharvested our forests and in so doing have triggered a cascade of environmental consequences: loss of vital habitat and biodiversity, soil erosion, and water pollution. We have overfished and overhunted and have allowed invasive species to devastate some of our most valuable ecosystems.

KEY CONCEPT 1.4

Modern humans inflict tremendous environmental impact by virtue of our sheer numbers and the high per-person impact of some societies.

In part, these problems stem from a disconnect in our understanding of the relationship between our actions and their environmental consequences. For example, unless they live close by, many people in the United States don’t realize that entire mountains are being leveled to produce their electricity; thousands of acres of habitat and miles of streams and rivers have been destroyed to access coal seams deep beneath the surface of West Virginia and Wyoming. We are slow to make the connection between the burning of that coal and mercury-contaminated fish or increased asthma rates.

We also face a suite of new problems that did not trouble the Vikings. Chief among them is population growth; as we will discuss in subsequent chapters, global population is poised to top 9 billion come 2050. The sheer volume of people will strain Earth’s resources like never before. This is relevant because every environment has a carrying capacity—the population size that an area can support indefinitely—but some of our actions are decreasing carrying capacity, even as our population swells. (See Chapter 4 for more on human populations and carrying capacity.) In addition, we generate more pollution than the Vikings did, and much of what we generate is more toxic.

carrying capacity

The population size that a particular environment can support indefinitely.

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“In part, these problems stem from a disconnect in our understanding of the relationship between our actions and their environmental consequences.”

Environmental scientists evaluate the impact any population has on its environment—due to the resources it takes and the waste it produces—by calculating its ecological footprint (see Chapter 6). Some analysts feel we have already surpassed the carrying capacity of Earth; our collective footprint already surpasses what Earth can support over a long period of time.

ecological footprint

The land needed to provide the resources and assimilate the waste of a person or population.

Anthropogenic climate change is another serious consequence of larger populations, increasing affluence, and more sophisticated technology. While the Vikings had to contend with periodic warming and cooling periods that were part of the natural climate cycle, the vast majority of scientists today conclude that modern humans are faced with rapidly warming temperatures caused largely by our own use of greenhouse gas-emitting fossil fuels. INFOGRAPHIC 1.4

anthropogenic

Caused by or related to human action.

MANY ENVIRONMENTAL PROBLEMS CAN BE TRACED TO THREE UNDERLYING CAUSES

Mads Nissen/Panos
© Oleksiy Maksymenko Photography/Alamy
Martin Roemers/Panos

We have something else in common with the Vikings of Greenland: Our attitudes frequently prevent us from responding effectively to environmental changes. According to Diamond, the Vikings were stymied by their own sense of superiority. They considered themselves masters of their surroundings, and so they did not notice signs that they were causing irreparable harm to their environment, nor did they bother to learn the ways of their Inuit neighbors, who had managed to survive in the same region for centuries before their arrival.

The United Nations’ Millennium Ecosystem Assessment is a scientific appraisal of current research that evaluates what is currently known about the ways in which environmental problems affect humans and makes recommendations about addressing those problems. According to its 2005 assessment, a consensus report of more than 1,500 scientists, human actions are so straining the environment that the ability of the planet’s ecosystems to sustain future generations is gravely imperiled. But there is hope: If we act now, the report’s authors write, we can still reverse much of the damage. Some of the best lessons about how we can do this come from the natural environment itself.

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