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The Basics of Climate Change

To understand climate change, we first need to go over what climate change is and how it happens. Climate change is happening because of greenhouse gases that humans release into the atmosphere. These greenhouse gases trap excess heat in the earth, warming our planet.

The most important GHG is carbon dioxide

Carbon dioxide makes up 76% of global (human) GHG emissions.

Climate change is when human actions significantly alter the natural climate.

In our case, it's warming the planet.

The greenhouse effect is how the earth naturally stays warm, and how greenhouse gas emissions (GHGs) are warming the planet.

Humans release GHGs, making the greenhouse effect too large.

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In Brief

Climate Change: In Brief

The United Nations Framework Convention on Climate Change (UNFCCC) defines climate change as "a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods." But what does that mean? In essence, climate change is when human actions significantly alter the natural climate.

We are already experiencing climate change. Human activities, most importantly fossil fuel combustion, are releasing dangerous substances called greenhouse gases (GHGs) into the atmosphere. GHGs are gases that trap heat in the earth's atmosphere. You can think of them as a greenhouse, which traps heat to grow plants. Collectively, these GHGs create the greenhouse effect, which is the earth's primary heat-trapping mechanism. The earth needs some of the natural greenhouse effect, but climate change is making it too much. 


This leads to too many GHGs in the atmosphere. That traps too much heat in the atmosphere, warming the earth. These warmer temperatures have profound impacts across the world.


The Greenhouse Effect


The greenhouse effect, as previously mentioned, is the natural warming of the earth due to heat-trapping greenhouse gases (GHGs). The greenhouse effect is what keeps the earth habitable. Too much of the greenhouse effect leads to the earth being too warm simply because too much heat is being trapped in the atmosphere. In short, the more GHGs, the more heat. But how does the greenhouse effect work? When sunlight comes into the earth's atmosphere, it is reflected back into the atmosphere in the form of infrared light, which is a type of invisible light. GHGs then absorb the majority of this infrared light, keeping it from escaping into outer space. 

Before humans started to burn fossil fuels, emitting GHGs, the concentration of carbon dioxide (the primary GHG that we measure) in the atmosphere was between 200 and 280 parts per million (ppm). This means that for every one million molecules in the atmosphere, 200 to 280 of them were carbon dioxide. However, since the Industrial Revolution, the concentration has increased to 416 ppm as of April 2021. This is the highest level in 800,000 years. That is a much longer timeframe than all of human civilization. What's most significant is that scientists have clear evidence that the greenhouse effect and humans' GHG emissions are the contributors to the warming they've observed. 

The Greenhouse Gases

The most significant GHGs are carbon dioxide, methane, fluorocarbons, and nitrous oxide. The Environmental Protection Agency (EPA) created the global warming potential (GWP) to compare how much each gas contributes to climate change. The GWP measures how much each gas warms the planet in comparison to carbon dioxide.

Carbon dioxide is the most significant GHG in regard to climate change. Since GWP is based on carbon dioxide, it has a GWP of 1. Though it is much less powerful than other GHGs, it is most important for two reasons. First, it makes up 76% of global GHGs and 80% of U.S. GHGs. Second, carbon dioxide stays in the atmosphere for a long time. 40% of all carbon dioxide stays in the atmosphere after 100 years, 20% after 1,000 years, and still 10% after 10,000 years. That means the effects of carbon dioxide will still be felt 10,000 years from now.

Methane is twenty-five times more potent (powerful) than carbon dioxide. That means it has a GWP of 25. Released especially by agricultural and industrial processes, methane is much less abundant than carbon dioxide but still quite dangerous. It can leave lasting damage to the environment even though it's only been around for about 100 years. 

Fluorocarbons are the most potent GHG. Fluorocarbons are a broad term for GHGs that humans created. They are only emitted by humans and are heavily regulated, leading to them only being 2% of all emissions. However, they are dangerously potent, with GWPs ranging from the 1,000s to the 10,000s. 

Nitrous oxide is most often emitted by agricultural processes, particularly soil management activities where fertilizers contain nitrogen which is then leaked from the soil into the atmosphere. Nitrous oxide has a GWP of 300 for the first 100 years. 


Global Warming vs. Climate Change

Global warming and climate change are two terms that mean different things. Throughout Kids Fight Climate Change and other resources, it will be important to know the difference. "Climate change" is a blanket term that refers to any effect of human activities. It is scientists' and advocates' preferred term because how climate change happens is different across the world. While some areas may be prone to drought, others may have more severe rainfall. Meanwhile, "global warming" is the more self-explanatory term, which refers to the primary effect of climate change, where the earth's average temperatures increase. In your writing and research, climate change is a better term because it promotes the idea of differences across the globe, refuting (combating) the idea that just because we have a harsh winter doesn't mean that climate change is "fake."


“Ask the Experts: The IPCC Fifth Assessment Report.” Carbon Management 5, no. 1 (February 2014): 17–25.

Denchak, Melissa. “Greenhouse Effect 101.” NRDC, July 16, 2019.

“Fact Sheet: Climate Change Science - the Status of Climate Change Science Today.” United Nations Framework Convention on Climate Change, February 2011.

Climate Change: Vital Signs of the Planet. “The Causes of Climate Change.” Accessed June 21, 2021.

US EPA, OAR. “Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases.” Reports and Assessments. US EPA, June 27, 2016.

US EPA, OAR. “Overview of Greenhouse Gases.” Overviews and Factsheets. US EPA, December 23, 2015.

US EPA, OAR. “Understanding Global Warming Potentials.” Overviews and Factsheets. US EPA, January 12, 2016.

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