Chapter 13 Human Impacts of the Environment

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

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