index > Today's Earth, Our Future > 4. The earth as a greenhouse > The Greenhouse Effect: The Special Layer Around Our Earth

The Greenhouse Effect: The Special Layer Around Our Earth

Do you know what "global warming" is? It's the term used to describe the effect of the earth getting warmer. And, do you know what causes this effect? Everyday, ?he earth gets light from the sun, whether it's sunny, cloudy or rainy. The earth's surface reflects this heat from the sun, or "solar heat," as something called "infrared rays," and sends it back out into the universe.

In this way, there is no heat that stays on the earth. The earth itself is in fact a very cold planet with a temperature of minus 18 degrees Celsius (-0.4 degrees Fahrenheit), where people and other living things cannot actually live. But fortunately for us, the earth is surrounded by a thin, see-through layer, which absorbs some of these infrared rays and then sends them through to the earth. Thanks to this layer, our earth is a much warmer planet of about 15 degrees Celsius (59 degrees Fahrenheit) on average. We couldn't live on the earth without this layer. What an incredible layer it must be, huh?

The earth is just like a greenhouse--one of those see-through buildings where people grow vegetables--or a glasshouse in a botanical garden for tropical plants. That's why we call this "greenhouse effect," which means that the earth keeps warm because of the see-through layer that surrounds it. It's as if the earth is in a large greenhouse.

We've gained a lot from being able to live in this sort of "greenhouse," but recently, the layer has gotten thicker and thicker, meaning that this layer absorbs more of the hot infrared rays and sends them back down to the earth. As a result, our earth is getting warmer and warmer. This is called "global warming."

An easy example of this is that when most of us feel cold, we put on more clothes like a sweat shirt or sweater to feel warmer, right? Imagine yourself wearing an extra sweater even though you already feel nice and warm. You'd feel too hot, wouldn't you? That's what's happening to our earth now.

Just what exactly is this "earth's sweater"? What is this "greenhouse" around the earth made of??

It's made up of something called "greenhouse gases." Gases such as carbon dioxide, methane and chlorofluorocarbons are all greenhouse gases.

Out of these three gases, carbon dioxide is the most harmful. It can be blamed for more than 60 percent of the cause of the greenhouse effect. Methane, the second most damaging gas that's responsible for about 20 percent of this effect, mainly comes from the waste from rice paddy fields and farm animals. The third most damaging are chlorofluorocarbons that cause about 10 percent of the harm. Chlorofluorocarbons mainly come from chemicals that are used to cool air conditioners and refrigerators. Since we are now aware that chlorofluorocarbons also damage the ozone layer, companies have replaced chlorofluorocarbons with a different gas that can do the same thing as chlorofluorocarbons but doesn't damage the ozone layer. Still, even this new gas adds to the greenhouse effect to some degree. Unfortunately, it's impossible to avoid some amount of global warming.

It's a tricky situation--without this layer of gases, we're in big trouble and we're in trouble with too much of it--and sadly enough, the more greenhouse gases there are, the more they will lead to greater problems with global warming in the future.

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