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