 Environmental scientists study how the natural world works, and how humans and the environment affect each other.

 The environment includes all the living and nonliving things with which organisms interact.

 Environment is often used to mean the nonhuman or “natural” world. But humans are a part of nature.

 Biotic factors: refer to the living organisms. Example: fish, bacteria, tree  Abiotic factors: refers to the non-living things. Example: water, soil, air

 Environmental science is the study of how the natural world works, how the environment affects us, and how we affect our environment.

 Understanding interactions between humans and the environment is the first step toward solving environmental problems.

 Environmental science is interdisciplinary which means it will involve more than one study of science including ecology, earth science, chemistry, biology economics, political science and others.

 Environmental science is the pursuit of knowledge about the world whereas environmentalism is a social movement dedicated to protecting the natural world.

 In the last several hundred years, both human population and resource consumption have increased dramatically. There are limits to our resources.

 Renewable resources can be replaced in a short period of time.  Nonrenewable resources cannot be replaced or it takes millions of years to replace.

 When they are used up, they are gone forever. Resources are considered sustainable if it can continue at the same rate into the foreseeable future.

 Renewable resources: fruits, grains, sunlight, wind energy, etc.  Nonrenewable resources: crude oil, natural gas, coal, copper, etc.  Sustainable resources: timber, water, soil, agricultural crops

 Recently our population has grown to about 7 billion people. We add about 78 million people to Earth every year, that’s more than 200,000 people a day. Population growth leads to many environmental problems. It’s not just the number of people but the amount of resources we consume.

 Ecological footprint expresses the environmental effects of an individual or population in terms of the total amount of land and water required:

 To provide the raw materials the individual/population consumes  To dispose of or recycle the waste the individual/population produces

 The ecological footprint is usually applied to humans but every organism, natural or synthetic object has a footprint.