New! Sign up for our free email newsletter.
Reference Terms
from Wikipedia, the free encyclopedia

Carbon dioxide

Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. It is often referred to by its formula CO2. It is present in the Earth's atmosphere at a low concentration and acts as a greenhouse gas. In its solid state, it is called dry ice. It is a major component of the carbon cycle.

Atmospheric carbon dioxide derives from multiple natural sources including volcanic outgassing, the combustion of organic matter, and the respiration processes of living aerobic organisms; man-made sources of carbon dioxide come mainly from the burning of various fossil fuels for power generation and transport use. It is also produced by various microorganisms from fermentation and cellular respiration. Plants convert carbon dioxide to oxygen during a process called photosynthesis, using both the carbon and the oxygen to construct carbohydrates. In addition, plants also release oxygen to the atmosphere, which is subsequently used for respiration by heterotrophic organisms, forming a cycle.

Related Stories
 


Earth & Climate News

January 5, 2026

CO2 can stimulate plant growth, but only when enough nitrogen is available—and that key ingredient has been seriously miscalculated. A new study finds that natural nitrogen fixation has been overestimated by about 50 percent in major climate ...
Overfished coral reefs are producing far less food than they could. Researchers found that letting reef fish populations recover could boost sustainable fish yields by nearly 50%, creating millions of extra meals each year. Countries with high ...
Microplastics in rivers, lakes, and oceans aren’t just drifting debris—they’re constantly leaking invisible clouds of chemicals into the water. New research shows that sunlight drives this process, causing different plastics to release ...
Scientists have discovered a clever way to turn carrot processing leftovers into a nutritious and surprisingly appealing protein. By growing edible fungi on carrot side streams, researchers produced fungal mycelium that can replace traditional ...
Scientists have uncovered an extensive underwater vent system near Milos, Greece, hidden along active fault lines beneath the seafloor. These geological fractures act as pathways for hot, gas-rich fluids to escape, forming clusters of vents with ...
The Arctic is changing rapidly, and scientists have uncovered a powerful mix of natural and human-driven processes fueling that change. Cracks in sea ice release heat and pollutants that form clouds and speed up melting, while emissions from nearby ...
A new catalyst design could transform how acetaldehyde is made from renewable bioethanol. Researchers found that a carefully balanced mix of gold, manganese, and copper creates a powerful synergy that boosts efficiency while lowering operating ...
Scientists have built the most detailed 3D models yet of temperatures deep beneath Greenland. The results reveal uneven heat hidden below the ice, shaped by Greenland’s ancient path over a volcanic hotspot. This underground warmth affects how the ...
Deep ocean hot spots packed with heat are making the strongest hurricanes and typhoons more likely—and more dangerous. These regions, especially near the Philippines and the Caribbean, are expanding as climate change warms ocean waters far below ...
A new eco-friendly technology can capture and destroy PFAS, the dangerous “forever chemicals” found worldwide in water. The material works hundreds to thousands of times faster and more ...
What we put on our plates may matter more for the climate than we realize. Researchers found that most people, especially in wealthy countries, are exceeding a “food emissions budget” needed to keep global warming below 2°C. Beef alone accounts ...
The search for life on Earth is speeding up, not slowing down. Scientists are now identifying more than 16,000 new species each year, revealing far more biodiversity than expected across animals, plants, fungi, and beyond. Many species remain ...

Latest Headlines

updated 12:56 pm ET