When people hear the word environment, they often think it has something to do with the people that protect the earth, but in truth the word environment is a scientific term. It means “all the living and nonliving things on Earth.” The living things include animals, plants, bacteria, algae, fungi, etc. The nonliving things include rocks, mountains, streams, lakes, rain, snow, and even clouds, oxygen, and carbon dioxide.
The earth has many cycles that keep it in balance. Everything is interconnected and affects everything else, in ways we may not even realize. The water cycle keeps moisture falling as rain and snow and evaporating back up to the clouds to fall again. The oxygen cycle depends on plants replenishing the oxygen that animals use and taking up the carbon dioxide they release. There is even an energy cycle where plants make energy from the sun and provide food for animals, which then release their nitrogen back into the environment when they die. That nitrogen is used to nourish new growing plants all over again. These cycles are how our environment is balanced.
Though the environment is in balance in many ways, it does change over time. Glaciers advance and retreat. Temperatures change, animals go extinct, and animals evolve. The continents slowly drift over millions of years. Volcanoes erupt and spew carbon dioxide into the air. Hurricanes flatten forests and change the shape of shorelines.
Though our planet may seem like a vast and powerful place, we are changing the earth's environment all the time too. There are over 6 billion people on Earth and our activities do affect the environment. We dam rivers, clear-cut forests, drain lakes, and create deserts. Interestingly, we may affect the planet in ways that actually will come back and hurt us!
This book will tell you about the environment, how it varies in different habitats, and how you affect it. You can see how people are trying to protect the environment and how you can make a difference. If you want to know how to protect the environment and get involved in being more “green,” that is called environmentalism. It's cool to be an environmentalist and our environment needs you!