Human Demographics

Demography The study of the growth rate, age structure and other characteristics of human populations Since industrial revolution, birth rates have remained fairly stable, but death rates have decreased dramatically  why? Growth rate is 1.6% 96 million people per year Doubling time of 43 years

This graph shows one factor affecting population growth. What is it? Predict how this factor will affect the population in each country between now and 2050. Brainstorm list of factors, events or conditions that might affect population growth in these countries.

Population Pyramids Shows age structures of populations Stable populations have an even distribution across most age classes A large number of young people indicates a growing population Growth momentum – the inherent future growth in a population that results form a disproportionately large fraction of the population being of younger age

Majority of people are in their pre-reproductive years Therefore, there will be a lot of births in the years to come Less industrialized countries ex. Kenya

Stable population Relatively equal number of individuals in each age groups (except for elderly since they naturally have a higher mortality rate than any other age group) Industrialized countries ex. United States

Few young people to reproduce in the future Majority of population is in post-reproductive years Low fertility rates and high mortality rates Ex. Japan, E. Europe

Demographic Transition Model Four-stage model describing relationship between economic development and changes in population patterns Preindustrial – harsh living conditions, high birth and death rates, slow population growth Transition – industrialization decreases death rates, birth rates still high, high population growth Industrial – birth rates decline, population begins to stabilize Postindustrial – birth and death rates balance, zero population growth

Trends in Human Population Growth Increased food supply due to improved agricultural methods and domestication of animals Breakthroughs in medicine enabled people to be treated for once-fatal illnesses Better shelter Improvements in storage capacity of food

Earth’s Carrying Capacity Humans have been able to increase the carrying capacity of Earth Population continues to grow exponentially Great disparity among countries in the amount of resources that are used per person Wealthiest 20% of population consumes 86% of world’s resources and produces 53% of world’s CO2 emissions People in poorest countries use 1.3% of world’s resources and produce 3% of CO2 emissions

Ecological Footprint The amount of productive land that is required for each person in a defined area for food, water, transportation, housing, waste management and other requirements 6 major categories: cropland, grazing land, fishing grounds, forest land, carbon absorption land, building area (available biocapacity) Estimated average per person globally is 2 hectares of land (1ha = 10 000m2)

Ecological Footprints from Around the World

Available Biocapacity Earth’s carrying capacity for the human population Approx. ¼ of Earth’s surface Does not include arid regions, open oceans, etc.