13.1 Physical Environments and Human Impacts

• Earth’s Environmental Systems

  • Ecosphere

    • Thin zone of

      • Air

      • Water

      • Earth

      • Living matter

    • Structure of the ecosphere is not eternal and unchanging

    • Composed of four layers of overlapping, interrelated parts:

      • Atmosphere

        • A thin blanket of air enveloping the Earth

      • Hydrosphere

        • Consists of the perpetually moving surface and subsurface waters

        • Water is essential to all life

        • Water plays a critical role in moderating the Earth’s climate

        • Hydrologic cycle

          • Changing form from vapor to liquid to ice/snow and back again

      • Lithosphere

        • The upper reaches of the Earth’s crust

          • Contains soils and support for plant life, animals, and other natural needs for living organisms

      • Biosphere

        • Consists of the living matter of plants and animals

        • Biomes

          • Dividents of the Biosphere which are biological communities

          • Established by the pattern of global climates

          • Ecosystems

            • Self-contained, self-regulating, and interacting communities adapted to local combinations of climate, topography, soil, and drainage conditions

            • Contain smaller, more specialized organisms

• Impacts on the Atmosphere

  • Ecosystems have long felt the destructive hand of humans and the cultural landscapes they made

  • At a global scale, however, human impact was minimal

  • Air pollution was at first local in the form of

    • Household air pollution

    • Negative health effects from indoor cooking over open fires

• Air Pollution and Acid Precipitation

  • Every day, thousands of tons of pollutants are discharged into the air by natural events and human actions

  • Atmospheric pollution can and does result in nature from

    • Ash from volcanic eruptions

    • Marsh gases

    • Smoke from naturally occurring forest fires

    • Windblown dust

      • These pollutants are of low volume and are widely dispersed in the atmosphere

  • Pollutants come primarily from burning fossil fuels

    • Coal

    • Oil

    • Natural gas

      • In power plants, factories, furnaces, and vehicles

        • Fires deliberately set to clear

        • Forests

        • Grasslands

          • They do this for agricultural expansion or shifting cultivation clearing and burning

  • Air pollution is a global problem today

  • The pollution shroud in and around India the researchers find it reduces sunlight enough to cut rice yields across much of the country

  • Air pollution worsened in the developing countries of South, Southeast, and East Asia

  • When acids from all sources are washed out of the air by

    • Rain

    • Snow

    • Fog

      • The result is acid precipitation

  • The Trouble with Ozone

    • Air pollution is the cause of the destruction of the Earth’s ozone layer

    • Ozone

      • Reactive molecule consisting of three oxygen atoms rather than the two of normal oxygen

      • In either hemisphere, ozone depletion has identical adverse effects

      • Ozone problems lead to greater exposure to UV radiation and it increases the incidence of skin cancer and, by suppressing bodily defense mechanisms, increases risk from a variety of infectious diseases

• Global Climate Change

  • Humans have significantly altered the chemical composition of the atmosphere

  • Human activities have increased the concentrations of three greenhouse gases

    • Carbon dioxide

    • Methane

    • Nitrous oxide

      • Intensifying the natural greenhouse effect which leads to global climate change

  • The Earth would be substantially colder and its temperatures would fluctuate wildly if the greenhouse effect did not exist

  • Carbon dioxide gets most of the media coverage

  • Nitrous oxide emissions are a byproduct of increased fertilizer use

    • This is a consequence of agricultural expansion and intensification

13.2 Impacts on Land Cover

• Humans have always managed to leave their mark on the landscapes that they occupy

• Search for minerals and other natural resources has altered whole landscapes

• Tropical Deforestation

  • Forest clearing accompanied the development of agriculture and spread of people throughout

    • Europe

    • Central Asia

    • Middle East

    • India

  • Desertification

    • Humans are negatively affecting the arid and semiarid regions of the world

• Soil Erosion

  • Soil

    • Complex mixture of rock particles, inorganic mineral matter, organic material, living organisms, air, and water

    • Soil is constantly being formed by the physical and chemical decomposition of rock material and by the decay of organic matter

13.3 Impacts on Water Resources

• Water is essential to all life on Earth

• Our bodies are about 60 percent water and about 70 percent of the Earth’s surface is covered by water

• Water Availability

  • Distribution, its availability, and its quality is the problem with water

  • Only about 1 percent of all water is available as liquid freshwater

  • Populations are rising in many regions where water supplies are limited

  • Transboundary river basins

    • Basins straddling two or more countries

• Water Use and Abuse

  • Water supplies and food supplies are intimately connected

  • In dry climates, rivers and lakes have shrunk or even disappeared due to irrigation demands

  • Environmental pollution

    • When humans introduce wastes into the biosphere in kinds and amounts that the natural system cannot neutralize or recycle

  • Human wastes often contain infectious agents that cause waterborne diseases such as

    • Cholera

    • Dysentery

    • typhoid fever

13.4 Wastes

• The most enduring of landscape evidence of human occupancy is the garbage produced and discarded by every society

• Solid Wastes

  • Solid wastes are generally landfills or incineration

  • Americans produce garbage and other municipal waste at a rate of about 2 kilograms per person per day

  • When the populations grow, the incomes rise, and the consumption patterns change

    • This means the volume of disposable materials continues to expand

  • The fastest-growing category of waste is electronic waste

• Toxic Wastes

  • Problems of municipal and household solid-waste management are having

    • Disposal of hazardous chemical or radioactive wastes

  • 10 percent of industrial waste materials are hazardous chemical or radioactive wastes

  • Disposed in highly regulated incinerators or lined landfills designed to prevent the release of contaminants into the environment

  • Radioactive Wastes

    • A facility that uses or produces radioactive materials generates at least low-level waste material where the radioactivity will decay to safe levels in 100 years or less

      • Examples of facilities that produce low-level radioactive waste materials

        • Nuclear power plants

        • Industries that manufacture radiopharmaceuticals

        • Smoke alarms

        • Consumer goods

        • Research establishments

        • Universities

        • Hospitals

• Exporting Wastes

  • There is no true “away”

  • Governments or industries have proposed to build

    • Landfills

    • Hazardous waste incinerators

    • Nuclear waste repositories

    • Communities

  • Organization of African Unity (OAU) adopted a 1988 resolution condemning the dumping of all foreign wastes on that continent

  • 80% of e-waste collected in the United States for recycling is exported to areas such as

    • China

    • India

    • Pakistan

    • Nigeria

    • Mexico

13.5 Future Prospects and Perspectives

• Humans have transformed the Earth’s landscapes since the end of the last glaciation

• Diverse systems of exploitation of the environment were developed in and diffused from distinctive cultural hearths

• Spatial interaction among regions did not halt the creation of distinctive regional subsystems of culture

• Human impact on the environment has shifted scales from the local or regional to the continental and global scales

• Things that can offer resources to guide human behavior in ways that are more respectful of the Earth

  • Religions

  • Belief systems

  • Cultures

• We can use scientific and technological advances to monitor and restore the environment