Animals get carbon by consuming plants and eating other animals that obtain carbon from food. Carbon moves from one living thing to another and circulates in the environment through the carbon cycle.
Carbon is bound to oxygen in carbon dioxide gas, and it transfers from the air to plants through photosynthesis. From plants, carbon goes to animals through the food chain. It becomes part of the soil when the remains of dead plants and animals decompose on the ground. Some of the buried, decayed remnants turn into fossil fuels after millions of years.
Carbon enters the atmosphere as living things expel carbon dioxide. The process of removing carbon dioxide from animals and plants is called respiration. Carbon also enters the atmosphere in the form of carbon dioxide when people use fossil fuels to generate power for factories, power plants and vehicles.
More than 5 billion tons of carbon are produced each year as fossil fuels are burned. Around 3.3 billion tons of the released carbon remains in the air, while most of the remaining carbon gets absorbed by bodies of water and dissolves in the water. Excessive carbon dioxide in the atmosphere traps heat and may have a significant impact on the warming of the planet.