Carbon dioxide is a chemical compound with the chemical formula CO2. It is a natural chemical compound organized with two oxygen atoms and a single carbon atom. Carbon dioxide has a pungent, colorless odor and a sour taste. This substance can remain in the atmosphere for fifty to two hundred years. It is formed in fermentation, during the combustion of carbon-containing materials, in organic decomposition and in animal respiration and is used by plants in the photosynthesis of carbohydrates. Not only the natural process that can produce carbon dioxide, man also participates in the production of carbon dioxide. The main contributors of human-produced carbon dioxide come from transportation, manufacturing and construction. In addition to the burning of fossil fuels in vehicle engines, deforestation is also the main factor increasing carbon dioxide emissions into the atmosphere. Humans can use carbon dioxide for many things, for example in the chemical industry, the food industry and the oil industry. Factories in the chemical industry use carbon dioxide to produce fire extinguishers. The food industry can use carbon dioxide to produce beverages such as carbonated water and carbonated soft drinks. Therefore, it is also often used for fermentation in the winemaking process to quickly cool the bunches of grapes. Carbon dioxide can be used by oil factories to improve oil recovery. There are also some negative effects of carbon dioxide that can be dangerous to human health and harmful to the world's environment. If humans inhale too much carbon dioxide, they will quickly feel tired, have poor vision and headaches. Additionally, carbon dioxide will increase the acidity of the blood, and a small change in blood pH will kill a person through acidosis. Carbon dioxide can control the atmosphere of paper. Recently, methane concentrations in the atmosphere have doubled, which is why it is important for us to reduce methane emissions. The main source of methane in the atmosphere is produced by human activity, such as the burning of forests and land and in the digestive process of ruminants. The production of methane by ruminants is influenced by two main factors: the digestibility of the feed and the quantity of feed consumed. Researchers and scientists in the animal nutrition sector are looking for ways to reduce methane emissions from ruminants such as cattle in order to improve livestock production and solve the environmental problem. In conclusion, not only can carbon dioxide damage the atmosphere, but methane also contributes to increasing the earth's temperature. We should reduce methane emissions to save and repair the world's environment.