Carbon dioxide is a colorless, odorless gas with the chemical formula CO₂, consisting of one carbon atom double-bonded to two oxygen atoms in a linear arrangement. Essential to life on Earth, CO₂ plays a crucial role in photosynthesis, where plants convert it into oxygen and organic compounds, while animals and humans exhale it as a waste product of cellular respiration. First identified as a distinct gas by Joseph Black in 1754, carbon dioxide makes up about 0.04% of Earth’s atmosphere, though this concentration has increased by over 50% since pre-industrial times due to fossil fuel combustion. While vital for maintaining Earth’s temperature through the greenhouse effect, elevated CO₂ levels are the primary driver of current climate change, making it simultaneously one of the most important and concerning molecules in modern environmental science.

Find a review of the 50 most important industrial gases here.

20 Fun Facts About Carbon Dioxide

Beyond the basics above, what else should we know about Carbon Dioxide? Check out the 20 fun facts below!

1. Solid CO₂ (dry ice) sublimes directly from solid to gas at -78.5°C (-109.3°F), making it perfect for fog effects and flash-freezing.
2. Carbon dioxide is 1.5 times heavier than air, which is why it can suffocate by pooling in basements, wells, and wine cellars.
3. The “fizz” in carbonated drinks comes from CO₂ forming carbonic acid, which triggers pain receptors on your tongue along with taste buds.
4. Venus’s atmosphere is 96.5% carbon dioxide, creating a runaway greenhouse effect with surface temperatures hot enough to melt lead.
5. Trees can absorb 48 pounds of CO₂ per year on average, with a single mature oak processing about 40,000 pounds in its lifetime.
6. Supercritical CO₂ (above 31°C and 73 atmospheres) acts like both a liquid and gas, used to decaffeinate coffee beans.
7. Your blood carries 3 times more CO₂ than oxygen by volume, mostly as bicarbonate ions that help regulate pH.
8. CO₂ fire extinguishers leave no residue and work by displacing oxygen, making them ideal for electrical fires and clean rooms.
9. The oceans have absorbed about 30% of human-produced CO₂, causing ocean acidification that threatens coral reefs and shellfish.
10. Submarines must “scrub” CO₂ from air using lithium hydroxide canisters, with each person producing about 1 kg daily.
11. Plants grow 30-50% faster in greenhouses enriched to 1,000 ppm CO₂, though this “fertilization effect” has limits.
12. Carbon dioxide lasers are powerful enough to cut steel and are the most common type used in industrial manufacturing.
13. Mosquitoes can detect CO₂ from human breath up to 100 feet away, using specialized neurons to track their targets.
14. The pressure in a CO₂ cartridge for pellet guns reaches 850 PSI at room temperature, dropping as the liquid evaporates.
15. Bread rises because yeast converts sugars into CO₂ and alcohol, with a single teaspoon producing about 30 liters of gas.
16. Lake Nyos in Cameroon released a massive CO₂ cloud in 1986, killing 1,746 people in one of nature’s strangest disasters.
17. The soft drink industry uses 3.7 million tons of CO₂ annually, with Coca-Cola alone consuming about 10% of the total.
18. CO₂ becomes a superconductor under extreme pressure (200 GPa), forming exotic crystalline structures never seen naturally.
19. Medical-grade CO₂ is injected during some surgeries to inflate body cavities, providing better visibility for laparoscopic procedures.
20. Antarctic ice cores show atmospheric CO₂ hasn’t exceeded 300 ppm in at least 800,000 years until the 20th century.

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