Ch. 4 The Human Population and the Environment Age structure Birth rate Death rate Demographic transition Growth rate Human carrying capacity Life expectancy Logistic carrying capacity Logistic growth curve Maximum lifetime Population Population dynamics Species Zero population growth

Age Structure Diagrams

Growth Rate Births – deaths = r Total population 20,000 births – 15, 000 deaths =. 01(x100 ) = 1.0% 500, 000 people

Average crude birth rateAverage crude death rate World All developed countries All developing countries Developing countries (w/o China) © 2004 Brooks/Cole – Thomson Learning

Human carrying capacity

Carrying capacity

Carrying capacity of Earth

How to determine human carrying capacity of Earth 1. extrapolate from past growth – logistic growth curve 2. packing problem approach Deep ecology

Life expectancy

Demographic Transition Model

Demographic Transition Preindustrial stage: little population growth. Living conditions are harsh. High birth and high death rate. Transitional stage: start of industrialization, higher food production, health care. Population booms Industrial stage: industry, medical care, etc now well established. Population growth slows. Most developed countries in this stage. Postindustrial stage: birth rate declines, population stable, then slowly decreases.

A Closer Look 4.1 – Growth of Human Population Stage 1 – Hunters and Gatherers Stage 2 – Preindustrial, Agriculture Stage 3 – The Machine Age Stage 4 – The Modern Era

Logistic Growth Curve Assumes: a constant environment a constant carrying capacity a homogenous population -Fig. 4.4 – inflection point -Used to forecast human population growth

Population and Technology T = P x I or I = PAT Total Impact = Population x Average Environmental Impact per person The average rich-nation citizen used 7.4 kilowatts (kW) of energy in 1990—a continuous flow of energy equivalent to that powering watt lightbulbs. The average citizen of a poor nation, by contrast, used only 1 kW. There were 1.2 billion people in the rich nations, so their total environmental impact, as measured by energy use, was 1.2 billion x 7.4 kW, or 8.9 terawatts (TW)—8.9 trillion watts. Some 4.1 billion people lived in poor nations in 1990, hence their total impact (at 1 kW a head) was 4.1 TW

Limiting Factors Categories – short-term, intermediate-term, and long-term Dispersal of certain pollutants, such as toxic metals, into water and fisheries - ? Soil erosion - ? Disruption of food distribution in a country caused by drought for instance -?

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