How a Greenhouse Gas Traps Heat

What makes carbon dioxide a greenhouse gas? Let’s discuss how they work.

Peer reviewed by Dr. Bryan Gitschlag

Misconceptions abound when it comes to human-caused climate change. Greenhouse gases are a central component of this theory, but how exactly do they work? This article seeks to break that down in a simple way.

One could veer off into the who and why, but today let’s keep things simple. I imagine there’s something special about gases like carbon dioxide and methane that make them trap heat. So, how do greenhouse gases function?

First, we’ll discuss a few basics like the Earth’s atmosphere compared to our neighbor — the Moon. Next, let’s find out what our atmosphere does with the Sun’s energy. Then, we will finish by learning how the form of a greenhouse gas affects its function.

Sun, Moon, and Atmosphere

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We learn in school how the Earth revolves around the Sun. The Sun shines its light on us in perpetuity, which both warms the Earth and nourishes life as we know it. Since the Moon is about the same distance from the Sun, why does it not have living creatures inhabiting it?

Temperature stability makes a big difference in habitability. Like how soil buffers nutrient and water uptake for plants, so does the atmosphere buffer the sun’s radiation. Our planet has enough mass to hold an atmosphere via gravity, whereas the moon does not.

Ergo, temperatures fluctuate wildly on the moon’s surface depending on whether it receives direct sunlight or lies in the shadow. In direct sun, the surface temperature can reach 106°C (224°F). On both the dark side of the Moon and in its craters, temps can dip to -183°C (-298°F). Temps vary so much because the Moon has no protection from the Sun or any buffers to keep its heat.

In contrast, the Earth has quite a thick atmosphere. It consists of roughly 78% hydrogen, 21% oxygen, and everything else is the tiny 1%. These include inert gases like argon, and carbon dioxide only makes up about 0.04%. Despite being such a small part, carbon dioxide’s effect outweighs its proportion to the whole. As a result, Earth’s temperatures can range from -89.2°C (-128.6°F) to 56.7°C (134°F).

Our Atmosphere and the Sun’s Energy

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the Sun bombards us with all kinds of energy, it is fortunate that our atmosphere shields us from most of the worst. The Earth’s ozone layer blocks Ultraviolet (UV) radiation, for example. About two-thirds of visible light makes it to the surface of the planet, though.

Another great thing about our atmosphere is how it retains heat, or infrared radiation, which emanates from the Earth’s surface energized by the sun. Thus, not only does our atmosphere block most of the excess or harmful energy, but it also retains heat during nighttime on the surface. As a result, Earth’s surface temperature stability proves far more hospitable than the wild fluctuations on the Moon’s surface.

How does an atmosphere absorb radiation like infrared heat? In physical science, many learn how water conducts electricity when you dissolve salt into it. Dissolving the salt ionizes the water, which means the components of the salt float around with electric charges.

Your body is similar in how it needs electrolytes. For example, we shouldn’t drink pure water. We need minerals dissolved into it, and our bodies use them to conduct electricity for things like muscle or nerve function. This same concept extends to our atmosphere.

How Greenhouse Gases Trap Heat

Image by Markus Nielbock from Pixabay

Radiation needs to bounce off molecules either with an electric charge or to stick around. Most of the gases in our atmosphere have a balanced electric charge, including nitrogen and oxygen molecules. The radiation bounces off these particles as they have a balanced shape and electric charge.

Other molecules like carbon dioxide and methane have a uneven distribution of electrons despite having balanced charges on paper. Greenhouse gases like water vapor hold most electrons towards one side, as oxygen likes to hoard them. This uneven shape allows the particle to absorb infrared heat through motion, i.e., through vibration and rotation.

This uneven shape allows the particle to absorb infrared heat through motion, i.e., through vibration and rotation.

Thank goodness they do! That tiny bit of carbon dioxide retains heat, and it kept our home in a stable condition for hundreds of millions of years. Otherwise, we would not exist to ponder about it.

What concerns us today is how each year, the average global temperatures rise. Human industrial activity hastened around 1750, and now 99% of all humans who have ever lived do so right now. We can compare carbon dioxide levels in glacial ice sheets, for example. Increases in human greenhouse gas output relate to a rise in average temperatures.

Conclusion

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See, that wasn’t so bad! Even I learned a thing or two in researching this article. Perhaps greenhouse gases seemed like an enigma, but I hope I broke it down into layman terms well enough.

Our Moon makes a good comparison since it’s roughly equidistant from the Sun. We compared the effects of the Sun’s energy on our atmosphere to the Moon’s lack of atmosphere. It’s safe to say we need the greenhouse effect to some extent, and the Moon provides a great contrast about why.

Like your body needs electrolytes, the atmosphere needs charged particles to conduct energy. Otherwise, we’d all burn and freeze daily; or we’d not have come into being. It’s the uneven distribution of electrons in molecules like water vapor, methane, and carbon dioxide which causes them to absorb heat through vibration and rotation.

While the greenhouse gases are getting jiggy with it up in the sky, we need to get jiggy with solutions. Don’t let greed prevent us from survival. May this post decrease roadblocks by dispelling misconceptions. Thank you for making it to the end, and I hope we can all thrive.