Demographic and Environmental Changes: c. 1900 - Present

AP Concept: 6.1 Science and the Environment
Key Concepts

Demographic Changes

Scientific advances in the use of vaccines, antibiotics, and sophisticated sewage systems improved life expectancy rates

However, longer life expectancy and changing lifestyles led to a rise in diseases such as diabetes, heart disease, and certain kinds of cancer

The Green Revolution in agriculture transformed farming and fed the world's growing population

Birth rates in the developing world increased dramatically throughout the 20^th century, despite birth control programs in India and the one-child policy in China

Migration increased in this period due to the growing population and lack of resources, as well as job opportunities elsewhere and political, religious, or ethnic persecution

Many people have moved to cities in rapid urbanization, which led to underemployment and the development of slums
External migrations have resulted in new cultural identities as well as anti-immigration movements
Conflict has led to great demographic shifts, as populations move to escape persecution in the Middle East

Epidemics have been able to spread more easily in this interconnected world, such as the 1918 influenza pandemic and AIDS

Environmental Changes

This huge population growth combined with rapid industrialization has led to significant environmental problems

Commercial overfishing has significantly depleted many oceanic fish species, leading to government regulation

Slash-and-burn agriculture and timber operations in tropical forests has resulted in deforestation

Water pollution destroys sources of fresh water, especially in developing nations

The use of petroleum and heavy metals has polluted the environment

The growing human population continues to generate greater amounts of trash, especially in industrialized societies

mountains of non-degradable trash sit in landfills or are sent to developing nations

Scientists believe that human actions may have contributed to global warming of the environment
However, humans have begun to take a more positive approach to the environment, focusing on how they can protect and preserve our natural resources

Groups like Greenpeace and the Sierra Club work to protect the environment through direct action and government lobbying

More Topics