First, it is important to understand that the atmosphere is extremely thin,it is just a few miles above the Earth's surface and it traps some amount of the sun's energy, or light radiation, as it hits the Earth. That's a good thing, the natural trapping of [the sun's radiation], because it keeps the temperatures within comfortable boundaries. While other planets are either too much hot or too much cold, Earth is just like Goldilocks—just right for life.

As humans add pollution like carbon dioxide (also known as CO2) into the air, the Earth's atmosphere becomes thicker. The thicker atmosphere traps more of the reflected radiation, raising the overall temperature. This process is what we call "global warming." Other major factors adding to global warming, include the burning of coal, oil, gasoline and forests.

What is global warming doing to the environment?

Global warming is affecting many parts of the world.  Global warming makes the sea rise, and when the sea rises, the water covers many low land islands.  This is a big problem for many of the plants, animals, and people on islands.  The water covers the plants and causes some of them to die.  When they die, the animals lose a source of food, along with their habitat.  Although animals have a better ability to adapt to what happens than plants do, they may die also.  When the plants and animals die, people lose two sources of food, plant food and animal food.  They may also lose their homes.  As a result, they would also have to leave the area or die.  This would be called a break in the food chain, or a chain reaction, one thing happening that leads to another and so on. 

The oceans are affected by global warming in other ways, as well.  Many things that are happening to the ocean are linked to global warming.  One thing that is happening is warm water, caused from global warming, is harming and killing algae in the ocean.

What is the greenhouse effect?

the Earth’s surface and atmosphere stay warm when gases in the air trap heat from the sun. Have you ever been inside a greenhouse, the all-glass buildings where plants are grown? They’re very warm, because the glass walls allow the sun’s rays in but prevent the heat from getting out.

Think of the earth as being inside a giant greenhouse. The gases act like a greenhouse’s glass walls -- they keep heat from escaping into space, and the earth stays warm.

Try this easy experiment: Take two jars and put a teaspoon of water in each jar. Put a lid on just one jar. Place both jars in a sunny spot. After a few hours, check on the jars. You’ll see that the open jar hasn’t changed, but the closed jar will be steamy and hot inside. What happened? The heat from the sun could not escape from the closed jar.

The greenhouse gases

The main gases that cause the greenhouse effect are:

- water vapor

- carbon dioxide, or CO2

- methane

- nitrous oxide

Some "greenhouse gases" occur naturally in the Earth’s atmosphere. But scientists measuring the gases say the amount of gases in the atmosphere has increased in the past few decades. For instance, the amount of CO2 in the atmosphere is 30% greater than what it was 150 years ago. Scientists believe CO2 levels will rise another 30% during the next 50 years.

The increase in greenhouse gases is expected to raise the average global temperature of the planet by 2 to 9 degrees Fahrenheit over the next 50 to 100 years.

Most of the increase is due to human activities, like:

- burning gasoline to drive cars and trucks

- burning oil, coal or wood to produce electricity

- for heating, cooling, and other purposes burning forests to clear land

All these activities, and many others, release greenhouse gases into the atmosphere. With greater amounts of greenhouse gases in the air, more heat will be trapped, and the Earth will get warmer...and warmer...and warmer

What might happen if Earth heats up?

If Earth gets hotter, some of the following things might occur:

-New coastlines would have to be drawn on maps! Because water expands as it is heated, and because oceans absorb more heat than land, sea levels around the world would rise. Cities on coasts would flood.

-Temperate places that now receive frequent rain and snowfall might become hotter and drier. Inland lakes and rivers would shrink. Forest fires could occur more often. Frequent periods of drought would make it hard to raise crops for food. There would be less water available for drinking, showers, irrigation, even swimming pools!

-Plants and animals unable to take the heat may go extinct, and be replaced by heat-tolerant species.

-Hurricanes, tornadoes and other storms caused by changes in heat and water evaporation might occur more frequently and be more intense.