A Growing Population Chapter 3 Section 2

Population Growth is Worldwide The rate of population growth has increased rapidly in modern times  World population was 3 billion people  World population doubled to 6 billion people. (40 years later)

Population Birthrate and Death Rate During different historical periods, populations grew at different rates. Demographers  know that population depends on the birthrate and death rate – Birthrate  the number of live births each year per 1,000 people – Death rate  the number of deaths each year per 1,00 people By comparing birthrates and death rates, demographers can figure out population growth.

Population Birthrate and Death Rate For centuries, the world population grew slowly. – No modern machinery = scarce amounts of food – Deaths because of diseases High birthrate, but also high death rate The life expectancy (the average number of years that people live) was short. – A hundred yeas ago in the US, men and women usually lived less than 50 years.

Reasons for Population Growth Today Birthrate has increased dramatically. The death rate has slowed. Populations in most countries have grown fast. – In some countries, the population doubles in less than 20 years. People live longer than ever. – US  women live to about 80 and men to 73 years

Reasons for Population Growth Today Two scientific developments have made this possible. 1. New farming methods have greatly increased the world’s food supply. – New varieties of important food crops have been developed – New ways to protect crops against insects – New fertilizers to enrich the soil – These changes in agriculture are called the Gree Revolution.

Reasons for Population Growth Today 2. Scientists have made advancements in medicine and health. – Today, new medicines and types of surgery treat health problems that used to kill people (i.e. heart disease and serious injuries). – Vaccines to fight diseases such as small pox, polio, and measles – Antibiotics to fight infections – As a result, many more babies are born and stay healthy, and people live many more years. – Population Growth Population Growth

The Challenges of Population Growth Growing populations use resources much faster than stable populations. – Some nations, like those in Southwest Asia, face shortages of fresh water and energy. – In Asia and Africa, food supplies cannot keep up with the growing population. – These countries do not have enough money to purchase imported food.

The Challenges of Population Growth Population growth puts pressure on all aspects of life. – Jobs – Schools – Decent housing – Transportation and sanitation

The Challenges of Population Growth Rapid population growth also effects the environment. – Forests in areas of India and Pakistan are disappearing. – Wood = building; fuel – Clean air supply Graphs on Pgs