Objectives Explain how the rate of human population growth is determined and compare the rates of growth over the last 100 years Distinguish between people overpopulation and consumption overpopulation. Explain why the rate of human population growth is important to the study of environmental science.

Human Population 1960 – 3 billion 1975 – 4 billion 1987 – 5 billion 1999 – 6 billion 2010 ~ 6.8 billion

Population & Resources Generalizations: 1.The resources essential to an individual’s survival are small, but a rapidly increasing population tends to overwhelm and deplete a country’s soils, forests, and other natural resources 2.In highly developed nations, individual resource demands are large, far above requirements for survival.

Nonrenewable Resources Resources present in limited supply, which do not replenish themselves in a reasonable timeframe. Includes: Minerals (aluminum, tin, copper, etc.) Fossil fuels (oil, natural gas, coal

Renewable Resources Replenished by nature relatively rapidly Includes: Trees Fisheries Agricultural land Fresh water Sun Renewable resources are only renewable if the are used in a sustainable way.

People & Consumption Overpopulation Overpopulation occurs if a country’s demand on resources results in damage to the environment People overpopulation-degradation of the environment occurs because there are too many people, even if those people consume few resources per person; currently a problem in developing countries Consumption overpopulation-results from consumption-oriented lifestyles common I highly developed countries.

Ecological Footprint The average amount of land, fresh water, and ocean required to supply a person with food, wood, energy, water, housing, transportation, and waste disposal billion acres – productive land and water on Earth 4.7 acres – average amount available to each person 5.7 acres – current avg. ecological footprint for the world’s population 23.7 acres - current avg. for U.S.

Ecological Footprints

The IPAT Model I = P x A x T (I) Environmental Impact (P) number of people (A) Consumption of resources per person (T) Environmental effects of the technologies used.

The IPAT model The environmental impact of CO 2 emissions from motor vehicles is a function of: Population The number of cars per person Average annual CO 2 emissions per vehicle