Let’s Review: What are the four factors that affect populations?

The study of human population dynamics: Demography How has the human population changed over time? Why do population growth rates vary in countries throughout the world? What is the ‘demographic transition’ and why should I care? The million dollar question:What is the ‘carrying capacity’ of the biosphere for humans?

Modelling human populations is important!

How long has Homo sapiens inhabited the planet? Follow the timeline of human evolution here... Homo Sapiens arrives 195,000 years ago ‘Agriculture’ begins 10,000 years ago Bronze Age: 5,000 years ago…

Global rate of population growth is now 1 billion/ 13 years. Until the 1800s the world's population grew slowly for thousands of years. 1820: 1 billion. 1970: 3 billion. 1999: 6 billion Global rate of population growth is now 1 billion/ 13 years.

Historical Overview Human Population growth 200 years of history in 4 minutes

High mortality rate Short life span Limiting Factors which maintained the prolonged lag phase for the human race Disease Primitive medical knowledge Primitive insulation Poor nutrition Primitive agricultural techniques Lack of sanitation High mortality rate Short life span

Watch this video and write down the reasons for the growth in the world’s population BBC report on the 7th Billion...

Reasons for rapid growth since 1820 Industrial revolution Progress in agricultural techniques – including Haber Process for Nitrogen fixation Improved sanitation Improved health care and medical knowledge More reliable, stable food supply Increased survival to reproductive age

Human Population Dynamic predictions Here are the United Nations Predictions for population change over the next 100 yearsUN World population prospects (Image: http://esa.un.org/unpd/wpp/P-WPP/htm/PWPP_Total-Population.htm) 7.12.12

When modelling human population dynamics, we commonly include: Birth rate (2012 global mean is 19.5/1000, cf 20.09 in 2007) Death rate (current ‘crude’ mortality rate is 8.37/1000) Age structure of the population : WHY? Migration

Birth/Death Rates For as long as birth rate outstrips death rates, the human race will continue to grow in size..

How does population growth vary in the world

Most population growth in the world is contributed by only 10 countries, with China and India leading

Developing countries account for 97% of global population growth

Global migration

Population (age-structure) profiles

let's look at population pyramids! Demographers predict future growth using models called ‘pyramids’/age-structure diagrams let's look at population pyramids!

Population pyramids: Developing Countries Developing countries typically have pyramid-shaped age pyramids, with high numbers of young, and relatively youthful age structures High infant mortality rates High (but decreasing) death rate

Population pyramids: Developed countries Low infant mortality Low death rate High proportion of population is over 60 years old

The Demographic Transition model

The Demographic Transition Model A 5 – stage model used to predict population dynamics as a country shifts from being a pre-industrial to an industrialised economic system

Demographic transition in a nutshell… Changes brought about by industrialisation, modernisation, lower the death rate Births greatly exceed deaths, resulting in rapid population increases (Stages 1,2) As modernisation increases, the birth rate falls and population growth decreases (stage 3) Birthrate falls to meet the death rate, and population growth stops (Stage 4,5)

Stage 1 High birth and high death rates Population size correlates highly with food supply ‘Pre-industrial’ (no countries are Stage 1 – few isolated communities…)

Mozambique, 2000: Stage 1 of the demographic transition model

Stage 2 Stable food supply and sanitation lead to huge drop in death rate Birth rates remain high Huge population increase

Mozambique, 2025: Stage 2 of the demographic transition model

Other countries currently in Stage 2 of the demographic transition Most ‘developing’ countries are in Stage 2: Much of South Saharan Africa *(except South Africa, Kenya, Botswana, Namibia, Ghana) Yemen Bhutan Laos

Stage 3 Birth rates start to fall as contraception is made available and fewer children needed to work Death rates still falling Population continues to rise

Countries in Stage 3 Countries in Stage 3

Stage 4 Total population high but balanced by low birth rate and low mortality Desire for smaller families Fertility rate may drop < 2.1 Population size stabilises

UK, 2000: Stage 4 of demographic transition

Other countries in Stage 4 Most wealthy countries are in Stage 4 Western Europe USA Canada Australia New Zealand South Korea Singapore

Stage 5 VERY low birth rate Low death rate Total population slowly decreasing Desire for smaller families People have children later in life

UK, 2025: Stage 5 of demographic transition UK in future Germany Japan Russia has lost 5.7 M since the breakup of the Soviet Union

Where is your country? Learning about the 'New Demography'

What does human demography mean for the future of our planet? Will today’s emerging nations pass through the demographic transition? Do you believe that national governments should implement policies, subsidies, or other programs to reduce birth rates? UN data...

Is population growth really a problem? Some say NO: People can find or manufacture additional resources to keep pace with population growth. Nations become stronger as their populations grow. Some say YES: Not all resources can be replaced. Even if they could, quality of life suffers. Nations do not become stronger as their populations grow.