Every time you breathe in, you remove oxygen and other elements from the air and when you exhale, you release carbon dioxide. Just like humans breathe plants breathe too, they breathe in the carbon dioxide that humans and animals make and turn them into energy during the process of photosynthesis and releases oxygen back into the air. Plants and animals are all made of carbon, when these organisms expire, fungi use the oxygen in the air to break down the carbon inside them and convert it into carbon dioxide, which is released back into the air. Bodies of water take in and release carbon from the surface, depending on the temperature. When humans burn fossil fuels, such as coal, petroleum, and natural gas, more carbon is released into the air in the form of carbon dioxide. All the extra carbon dioxide in the air is contributing to global warming which is melting the ice caps.