Modern technology has altered the historic relationship between people and the environment. People are now the most important agents of change on Earth, and they can modify the environment to a greater extent than in the past. Geographers are concerned that people sometimes use modern technology to modify the environment insensitively. Human actions can deplete scarce environmental resources, destroy irreplaceable resources, and use resources inefficiently.

Ecology & The Biosphere

The fourth natural resource system, the biosphere, encompasses all of Earth’s living organisms. Because living organisms cannot exist except through interaction with the surrounding physical environment, the biosphere also includes portions of the three abiotic systems near Earth’s surface. Living organisms in the biosphere interact with each of the three abiotic systems. For example, a piece of soil may comprise mineral material from the lithosphere, moisture from the hydrosphere, pockets of air from the atmosphere, and plant and insect matter from the biosphere.

Most of the living organisms interact within the top 3 meters (10 feet) of the lithosphere, the top 200 meters (650 feet) of the hydrosphere, and the lowest 30 meters (100 feet) of the atmosphere:

• The lithosphere is where most plants and animals live and where they obtain food and shelter.

• The hydrosphere provides water to drink and physical support for aquatic life.

• The atmosphere provides the air for animals to breathe and protects them from the Sun’s rays.

A group of living organisms and the abiotic spheres with which they interact is an ecosystem. The scientific study of ecosystems is ecology. Ecologists study interrelationships between living organisms and the three abiotic environments as well as interrelationships among the various living organisms in the biosphere.

Ecosystem: White Cliffs of Dover, United Kingdom

The city of Dover, United Kingdom, sits atop a lithosphere of chalky cliffs, beside the hydrosphere of the English Channel, beneath the atmosphere above, and surrounded by a green biosphere. Geographers are especially interested in the ecosystem of a city because more than half of Earth’s humans live in urban areas. The lithosphere provides the ground and the materials to erect homes and businesses. The hydrosphere provides the water for urban dwellers to consume. The atmosphere is where urban dwellers emit pollutants. Some plants and other animals of the biosphere thrive along with humans in the cities, whereas others struggle.

Human geographers are especially interested in ecosystems involving the interaction of humans with the rest of the biosphere and the three abiotic spheres:

• If the atmosphere contains pollutants, or its oxygen level is reduced, humans have trouble breathing.

• Without water in the hydrosphere, humans waste away and die.

• A stable lithosphere provides humans with materials for buildings and fuel for energy.

• The rest of the biosphere provides humans with food.

Human actions are sustainable if they preserve and conserve elements of the four spheres and unsustainable if they cause destruction. For example, human actions contribute to the destruction of soil, the material that forms on Earth’s surface at the thin interface between the air and the rocks. Two sustainability issues arise from the destruction of soil:

• Erosion. Erosion occurs when the soil washes away in the rain or blows away in the wind. Farmers contribute to erosion through inappropriate choices. To reduce erosion, farmers can avoid steep slopes, plow less, and plant crops whose roots help bind the soil.

• Depletion of nutrients. Soil contains the nutrients necessary for successful growth of plants, including those useful to humans. Nutrients are depleted when plants withdraw more nutrients than natural processes can replace. Each type of plant withdraws certain nutrients from the soil and restores others. To minimize depletion, farmers can plant different crops from one year to the next so that the land remains productive over the long term.

Conservation and Restoration Ecology

Cultural Ecology

Human geographers are especially interested in the fact that different cultural groups modify the four spheres in distinctive ways. The geographic study of human–environment relationships is known as cultural ecology. The roots of cultural ecology reach back more than 200 years, to an era when early scientists traveled the globe, observing how people lived in different environments.

Environmental Determinism

Pioneering nineteenth-century German geographers Alexander von Humboldt (1769–1859) and Carl Ritter (1779–1859) believed that the physical environment caused social development, an approach called environmental determinism. According to Humboldt and Ritter, human geographers should apply laws from the natural sciences to understanding relationships between the physical environment and human actions. They argued that the scientific study of social and natural processes is fundamentally the same.

Other influential geographers adopted environmental determinism in the late nineteenth and early twentieth centuries. Friedrich Ratzel (1844–1904) and his American student Ellen Churchill Semple (1863–1932) claimed that geography was the study of the influences of the natural environment on people.

Another early American geographer, Ellsworth Huntington (1876–1947), argued that climate was a major determinant of civilization. For instance, according to Huntington, the temperate climate of maritime northwestern Europe produced greater human efficiency as measured by better health conditions, lower death rates, and higher standards of living.

Possibilism

To explain relationships between human activities and the physical environment, modern geographers reject environmental determinism in favor of possibilism.

According to possibilism, the physical environment may limit some human actions, but people have the ability to adjust to their environment. People can choose a course of action from many alternatives in the physical environment.

The climate of any location influences human activities, especially food production. From one generation to the next, people learn that different crops thrive in different climates. For example, rice requires plentiful water, whereas wheat survives on limited moisture and actually grows poorly in very wet environments. On the other hand, wheat is more likely than rice to be grown successfully in colder climates. Thus, according to possibilism, people can choose the crops they grow and yet be compatible with their environment.

Some human impacts on the environment are based on deep-seated cultural values. Why do we plant our front yard with grass, water it to make it grow, mow it to keep it from growing tall, and impose fines on those who fail to mow often enough? Why not let dandelions or wildflowers grow instead? Why does one group of people consume the fruit from deciduous trees and chop down the conifers for building materials, whereas another group chops down the deciduous trees for furniture while preserving the conifers as religious symbols? Are some of these actions more sustainable than others?

A people’s level of wealth can also influence its attitude toward modifying the environment. A farmer who possesses a tractor may regard a hilly piece of land as an obstacle to avoid, but a poor farmer with a hoe may regard hilly land as the only opportunity to produce food for survival through hand cultivation.

Sustainability & Our Environment

Climate Change & Rising Seas

Climate change has raised the global sea level about 8 inches since 1880, and by nearly 2 feet along the U.S. East Coast. The interactive map at SurgingSeas.org shows different amounts of flooding, depending on the level of sea level rise. A better resource is Sea Level Rise Viewer from NOAH https://coast.noaa.gov/slr/

Explore the Sea Level Riser Viewer and see how sea level rising effects at least three areas.