![]() Those fuels power our cars, electronics and more. Burning fossil fuels, such as coal, oil and gas, releases lots of CO 2. There has been a relative balance between the sources that spewed it and the processes that removed it. Despite its proximity to the sun, the surface of Venus would be far cooler if the planet had only a thin, Earth-like atmosphere.įor much of history, Potosnak says, levels of CO 2 in the air have risen and fallen naturally. Its thick, dense atmosphere has led to surface temperatures that average a blistering 453° Celsius (847° Fahrenheit). In recent decades, Earth’s greenhouse effect has shown signs of being out of control. SolStock/E+/Getty Images Runaway greenhouse warming How much of this gas is taken up by plants can affect the rate of global warming. Scientists continue to study photosynthesis in plants to better understand the role of carbon dioxide in Earth’s ecosystems. Instead of feeling warmed on a cool night by a cozy blanket, many organisms now feel as though they’re lying under a pile of thick blankets in the middle of summer. And it’s now much higher than most ecosystems have evolved to find comfortable. (By January 15, 2023, it was 420.45 ppm at a monitoring station atop Hawaii’s Mauna Loa observatory.) Like a thick blanket, this growing excess traps more heat. In recent years, global CO 2 levels in Earth’s atmosphere have risen dramatically - to roughly 415 parts per million. But there can be too much of a good thing. Thus, Mars simply can’t hold much of the energy it receives from the sun.įor much of Earth’s history, that greenhouse effect has helped the planet maintain temperatures that support life. Mars, by contrast, is very cold - partly because it’s not massive enough to hold onto much of an atmosphere. Perhaps the gas helps warm that distant planet as well.) (The James Webb Space Telescope has discovered evidence of CO 2 on an exoplanet. Earth would be largely uninhabitable without it. Just like the glass walls of a greenhouse trap heat inside a building’s structure, CO 2 acts like a blanket to hold heat close to our planet’s surface. It helps warm Earth’s surface through what’s known as the greenhouse effect. Over the eons, CO 2 began accumulating in Earth’s atmosphere. In this way, life on Earth recycles oxygen and CO 2.īesides living organisms, other natural sources of this gas include volcanic eruptions and fires. This greenery then “exhales” oxygen, releasing it back for animals and other organisms to use. (Many microbes do, too.) Plants “breathe in” this CO 2 and use it for photosynthesis. A warm, life-sustaining jacketĪnimals - be they humans, whales, turtles, fish or insects - “exhale” CO 2 when they breathe. But since fire cannot burn without oxygen, CO 2 is used in some fire extinguishers as a quick, effective way to douse flames. In some cases, this can cause a person - or other animal - to suffocate. If CO 2 builds up rapidly, such as at the bottom of a tunnel or in an enclosed room, this gas will push oxygen out of its way. It’s also the source of the fizz in carbonated drinks.ĬO 2 is heavier than air, which means it will sink. (Always be careful around dry ice! It can cause frostbite quickly.)ĬO 2 can be captured in high-pressure canisters and used to inflate bicycle tires or power paintball guns. If you’ve ever walked through a haunted house with a so-called “smoke” machine, the fog is likely vapor from a block of dry ice. This “dry ice” looks snowy white and can transform directly from a solid to gas. But cool it to -78° Celsius (-109° Fahrenheit) and it turns solid. ![]() “But with three atoms all in a line, CO 2 can wiggle the oxygens at each end.” This helps the molecule absorb heat when the sun’s rays hit it.Īt typical conditions on Earth, CO 2 is colorless and odorless. “Molecules with just two atoms, like oxygen (O 2) and nitrogen (N 2), really can’t wiggle much,” he says. He describes CO 2 molecules as being able to “flap their wings” a little bit. Mark Potosnak is an Earth scientist at DePaul University in Chicago, Ill. ![]() (The CO 2 molecule is also nonpolar, which means that all of the electric charges inside it are spread out relatively evenly.) This means that the carbon shares two pairs of electrons - four electrons in all - with each of the oxygen atoms. One reason it forms this straight-line shape is its two double covalent (Koh-VAY-lunt) bonds. If you could zoom in to see a single molecule of CO 2, it would look like a straight line with a carbon atom in the center and oxygen atoms at either end. Science Photo Library/Science Photo Library/Getty Images The gray attachments show the double bonds that give this molecule its straight-line structure. This illustration of a molecule of carbon dioxide shows a central carbon atom (black) linked to oxygen atoms (red) at either end. ![]()
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