Buoy 2 AIR:
Air is made up of oxygen, nitrogen, carbon dioxide and water vapour. Until the beginning of the last century, the Earth’s atmosphere was relatively constant. Plants took up carbon dioxide, made food and released oxygen into the air. Animals took up oxygen to breathe and released carbon dioxide into the air. Things were in BALANCE. With the burning of fossil fuels, the level of carbon dioxide in the atmosphere has increased considerably, as also have methane, CFC’s and nitrous oxides. These are known as the GREENHOUSE GASES and cause GLOBAL WARMING by forming a thick layer of gases insulating the Earth. It is these gases that are the main cause of global warming and climate change.
