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What Are Greenhouse Gases and Where Do They Come From?

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Climate change is primarily caused by the accumulation of greenhouse gases, or heat-trapping gases, in the atmosphere. Greenhouse gases are certain molecules in the air that have the ability to trap heat in the Earth's atmosphere. Some greenhouse gases, like carbon dioxide (CO2) and methane (CH4), occur naturally and play an important role in Earth's climate. If they didn't exist, the planet would be a much colder place. However, some human activities, such as mining and burning fossil fuels (like coal, oil and natural gas) for energy and transportation, emit molecules of CO2 and other greenhouse gases. These activities cause greenhouse gases to accumulate in the air, and as these molecules build up in the atmosphere they cause an overall warming of the planet. Some greenhouse gases are entirely man-made and are products of certain industrial processes.

Play the video to see sources of the main greenhouse gases.

Not all greenhouse gases are created equal in terms of contributing to climate change. Their impact varies according to how long they remain in the atmosphere and how efficient they are at trapping heat. For example, methane, the main component in natural gas, remains in the atmosphere for a shorter time than CO2, but is far more efficient at trapping heat, making it a more potent greenhouse gas. Nitrous oxide is less abundant than methane, but even more efficient at trapping heat, and it stays in the atmosphere for a long time. Understanding the impacts and sources of the main greenhouse gases can help inform strategies to reduce greenhouse gas emissions.

For more information, check out the EPA's resources on greenhouse gases.

Discussion Questions

  • What does the term "greenhouse gas" mean?
  • What role do greenhouse gases play in climate change?
  • What is the most prevalent greenhouse gas?
  • What are some of the major sources of greenhouse gases?
  • Which greenhouse gases do you think are of greatest concern in terms of global warming? Why?

This video explainer is part of our Clue into Climate collection of resources.

This video explainer is featured in our Clue into Climate e-book series. Click on the tabs below to download our free e-books and subscribe to our iTunes U course. You can also visit our e-books page to view our other offerings.

Climate e-book cover 1

Look into the causes of climate change, and discover how scientists develop and use climate models.

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Climate e-book cover 2 web

Learn about how climate change influences precipitation patterns and how it impacts our frozen landscape.

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Climate e-book cover 3 updated web

Investigate shifts in the distribution of plant and animal species due to climate change, and the effects of increased carbon dioxide emissions on the ocean.

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Climate e-book cover 4 web

See how communities are preparing for sea level rise and other impacts of climate change, and ways we can help minimize future climate change.

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