In this section:
A ‘blanket’ of atmospheric gases traps heat around our planet and keeps it warm. The ‘blanket’ includes gases like carbon dioxide and methane that contain carbon. As the concentration of gases increases, more heat is trapped and the average temperature of the Earth goes up.
Carbon is central to the flow of energy around the Earth. It is a naturally occurring element that’s present in all living things. Carbon forms bonds with other elements to create thousands of different compounds including fossil fuels like peat, oil, coal and shale; and is in gases like carbon monoxide, carbon dioxide and methane.
Carbon flows through air, sea, land, plants, animals and people. It’s in our food, and everything we use.
When the sun shines on plants they take in carbon dioxide from the air and use the carbon to make glucose (sugar), the basic building material for plants, and a fuel for living things. Plants store the sugar in leaves, stems and roots. When we eat plants we burn their stored glucose as a source of energy. This involves a chemical reaction that produces carbon dioxide, which we breathe back into the air.
What’s a fossil fuel?
When masses of dead plants were buried millions of years ago and subjected to intense geological pressure they turned into coal, oil or gas. They are all called ‘fossil fuels’ because they’re made from ancient plants. Fossil fuels provide most of the energy we use in Australia. Most of our electricity is generated by coal-fired power stations. Most transport depends on petrol or diesel made from oil, and natural gas provides heat for industry and households. Burning fossil fuels releases carbon that was trapped in plants millions of years ago. Every year Australia releases about 20 tonnes of carbon dioxide per person.
Carbon goes round and around
Since the Industrial Revolution in the the late 1700s, people have been digging up fossil fuels and burning them at an increasing rate. We’re transferring carbon from deep in the Earth into the atmosphere. Atmospheric carbon dioxide levels are now higher than they’ve been in 800 000 years. Where they stop will depend on what we do next. Instead of transferring more carbon to the atmosphere we can harness other sources of energy like wind, sun and waves and become much more efficient in our use of energy.
The greenhouse effect
Carbon dioxide gas is, with other gases, forming a ‘blanket’ that absorbs and traps heat around the Earth. Although the main greenhouse gas is water, carbon dioxide absorbs part of the sun’s energy that isn’t absorbed by water so it has a significant effect. The more carbon dioxide there is in the atmosphere, the greater the potential for heat build-up.