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?
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