What Is Greenhouse Gas? - Definition, Causes & Effects

Lesson Transcript
Instructor: Elizabeth Friedl

Elizabeth, a Licensed Massage Therapist, has a Master's in Zoology from North Carolina State, one in GIS from Florida State University, and a Bachelor's in Biology from Eastern Michigan University. She has taught college level Physical Science and Biology.

You hear a lot about greenhouse gases and the greenhouse effect these days, but what exactly is a greenhouse gas? You may be surprised to learn that greenhouse gases are not only naturally occurring, but are also essential to life on Earth.

The Greenhouse Effect

In order to understand greenhouse gas, we must first understand the larger concept of the greenhouse effect. To do so, let's use a metaphorical example: Think of a car on a hot summer day. After it sits for a long time in the sun with the windows up, it gets pretty hot in there! Sunlight comes in through the windows and warms the car's interior. If the windows are completely closed, there is no place for this heat to escape. But if the windows are cracked, this creates a place for some of the heat to leave the car. When it comes to climate and environmental science, the earth is very much like the car, and greenhouse gases are very much like the windows.

Greenhouse gases allow sunlight to pass through the atmosphere and reach the earth's surface. Some of this sunlight is captured as heat on Earth, and some of it is radiated back toward space. When greenhouse gases are present in the right amounts, they trap just enough heat to keep the earth warm enough for organisms to survive while letting some of that heat back into space. Without greenhouse gases, the earth would be a very chilly 0° F (-18° C). This trapping of heat under the atmosphere is called the greenhouse effect.

So, if greenhouse gases are so good for us, why do they get such a bad reputation? The problem with greenhouse gases is that they need to be present in specific amounts. When too little gas is present, not enough heat is trapped under the atmosphere to keep the earth warm. When too much gas is present, too much heat gets trapped, which warms the earth more than usual. The types and amounts of greenhouse gases in the atmosphere are only beneficial when they are present in just the right balance.

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  • 0:00 The Greenhouse Effect
  • 1:55 Greenhouse Gas Defined
  • 2:25 Causes and Effects
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Greenhouse Gas Defined

The earth's atmosphere is made up of many different types of gases, each of which contributes to the greenhouse effect differently. The most important greenhouse gases are:

  • Water vapor
  • Carbon dioxide
  • Methane
  • Nitrous oxide
  • Fluorinated gases

So in essence, a greenhouse gas is simply any atmospheric gas that traps heat within the atmosphere. This trapped heat creates the greenhouse effect, which in turn, contributes to climate change.

Causes and Effects

Greenhouse gases are naturally present in the atmosphere, but human production has been increasing the concentration of these gases faster than they can naturally break down. This increase is mainly due to the burning of fossil fuels, such as coal, oil, and natural gas and excess methane production from livestock and landfills.

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