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The ecological footprint

The measure of human demands on Earth’s natural resources is known as our ecological footprint. Currently, we use the equivalent of 1.5 Earths to produce all the renewable resources we use. As the human population grows, the challenge of reducing our footprint becomes more urgent.

Impacts

Every human produces an individual ecological footprint that is determined largely by the wealth and level of development in the country they live in—more developed countries have a larger footprint on average—but the choices we make in our daily lives also contribute. Driving a car, running clothes through a dryer, turning on the air conditioning—these are activities that add up to a larger footprint.

If everyone in the world lived like the residents of the U.S., humanity’s annual demand on nature would equal a whopping 4 Earths per year. Only the residents of four countries—Qatar, Kuwait, United Arab Emirates and Denmark—have larger average footprints.

By adding up the natural resources withdrawn from Earth, we can calculate the human footprint on the planet—a measure of how much we are using the Earth’s natural resources. The withdrawals come in six categories:

Carbon

A measure of carbon emissions, represented by the amount of forest land that would be needed to sequester carbon dioxide emissions, not including the fraction that is absorbed by the oceans and leads to acidification.

Cropland

The amount of cropland used to grow plants for food, fiber, animal feed, and commodities including oil, soy and rubber.

Grazing land

The amount of grazing land used to raise livestock for meat, dairy products, hide and wool.

Forests

The extent of forests required to supply timber, pulp and fuel wood. Fishing grounds: The estimated primary production required to support the fish and seafood caught in freshwater and marine environments.

Fishing grounds

The estimated primary production required to support the fish and seafood caught in freshwater and marine environments.

Built up land

The amount of land covered by human structures, including transportation, housing, industrial structures and reservoirs created by dams.