The greenhouse effect

The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be about 16ºC colder. Because of how they warm our world, these gases are referred to as greenhouse gases.

The Earth’s atmosphere is all around us. It is the air that we breathe. Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse. Sunlight enters the Earth's atmosphere, passing through the blanket of greenhouse gases. As it reaches the Earth's surface, land, water, and biosphere absorb the sunlight’s energy. Once absorbed, this energy is sent back into the atmosphere. Some of the energy passes back into space, but much of it remains trapped in the atmosphere by the greenhouse gases, causing our world to heat up.

The greenhouse effect is important. Without the greenhouse effect, the Earth would not be warm enough for humans to live. But if the greenhouse effect becomes stronger, it could make the Earth warmer than usual. Even a little extra warming may cause problems for humans, plants, and animals.

It may seem hard to believe that people can actually change the Earth’s climate. But scientists think that the things people do that send greenhouse gases into the air are making our planet warmer.

Once, all climate changes occurred naturally. However, during the Industrial Revolution, we began altering our climate and environment through agricultural and industrial practices. The Industrial Revolution was a time when people began using machines to make life easier. Since the Industrial Revolution, the need for energy to run machines has steadily increased. Some energy, like the energy you need to do your homework, comes from the food you eat. But other energy, like the energy that makes cars run and much of the energy used to light and heat our homes, comes from fuels like coal and oil – fossil fuels. Burning these fuels releases greenhouse gases.

When Do You Send Greenhouse Gases into the Air?

Whenever you ...

• Watch TV

• Use the Air Conditioner

• Turn on a Light

• Use a Hair Dryer

• Ride in a Car

• Play a Video Game

• Listen to a Stereo

• Wash or Dry Clothes

• Use a Dish Washer

• Microwave a Meal

... you are helping to send greenhouse gas into the air.

To perform many of these functions, you need to use electricity. Electricity comes from power plants. Most power plants use coal and oil to make electricity. Burning coal and oil produces greenhouse gases.

Other things we do send greenhouse gases into the air too;

The trash that we send to landfills produces a greenhouse gas called methane. Methane is also produced by the animals we raise for dairy and meat products and when we take coal out of the ground. Whenever we drive or ride in a car, we are adding greenhouse gases to the atmosphere. And, when factories make the things that we buy and use everyday, they too are sending greenhouse gases into the air. When we just go on with loving how we live, we might ruin our planet. Horrible consequences might follow:

Human Health

Climate change may affect people's health both directly and indirectly. Indirectly, ecological disturbances, air pollution, changes in food and water supplies, and coastal flooding are all examples of possible impacts that might affect human health. Very young children and the elderly adults will run the highest risks.

Ecological Systems

Climate change may change the world's habitats and ecosystems – all living things rely on these places.

Sea Level Rise

Global warming may make the sea level become higher. Why? Well, warmer weather makes glaciers melt. A glacier is a large sheet of ice that moves very, very slowly. Some melting glaciers add more water to the ocean. Warmer temperatures also make water expand. When water expands in the ocean, it takes up more space and the level of the sea rises.

Crops and Food Supply

Global warming may make the Earth warmer in cold places. People living in these places may have a chance to grow crops in new areas. But climate change also might bring droughts to other places where we grow crops. In some parts of the world, people may not have enough to eat because they cannot grow the food that they need.