CHAP TER 1 History Weather Is Always Changing Environmentalism is a big word But its meaning is simple Practicing environmentalism means being a friend of Earth and all its creatures Environmentalists want to keep our air healthy our land clean and our water fresh They want to take care of our plants and animals by making sure our planet remains a safe place to live Some environmentalists focus on encouraging people to stop polluting Others encourage people to recycle One of the most important environmental jobs is to teach people about climate change The Story of Climate Change Earth has been around for about 4 5 billion years Throughout all these years the climate has always been changing During 4 21st century skills library
Many people care about protecting Earth from climate change 5 55 Global Citizens Environmentalism
The greenhouse effect is part of Earth’s natural way of keeping us warm 6 6 21st century skills library
some time periods the planet is hotter Other times the planet is covered entirely in ice But researchers believe that today’s climate change is different Studies indicate that human actions may be contributing to climate change Scientists have known about climate change for almost 200 years In 1827 French mathematician Joseph Fourier learned that Earth’s atmosphere traps heat from the sun like a greenhouse Today we call this the greenhouse effect Atmosphere is the air surrounding Earth It is made up of different gases including nitrogen oxygen argon and carbon dioxide These gases work together If there were no atmosphere the sun’s heat would bounce off Earth and head back into space Earth would be freezing cold and nothing would survive In 1896 Swedish scientist Svante Arrhenius began to think the atmosphere was changing He thought that there was more carbon dioxide in it than there should be In 1958 scientist Charles David Keeling proved Arrhenius right By collecting data Keeling proved that there was 10 percent more carbon dioxide in the atmosphere than just a century before Carbon dioxide is a gas that absorbs the heat from the sun The more carbon dioxide in the atmosphere the hotter our temperatures become 7777 Global Citizens Environmentalism
