How greenhouse gases increase

Many greenhouse gases are produced naturally in our environment.

Carbon dioxide is the main greenhouse gas. Humans and other animals release it into the atmosphere with every breath.

It is also released when a fuel such as wood or a fossil fuel is burnt. Through a chemical change, oxygen is burnt and carbon dioxide is created.

Nature has methods for balancing the emission of carbon dioxide. Trees use carbon dioxide in photosynthesis, the process by which they make their food. Large bodies of water, such as seas and oceans, can also absorb some carbon dioxide. Over time these, and other natural processes, have managed the amount of carbon dioxide in the upper atmosphere, preventing the earth from becoming too hot or too cold for life to exist.

However, with industrialisation we have enormously increased the amount of fossil fuels being burnt. Our powerplants and factories burn tonnes and tonnes of fuel every day. Petrol, derived from oil, is used to power millions of vehicles around the world.

At the same time, humans have cut down forests, concreted over grass and otherwise reduced the number of plants in the world. This means the world has fewer plants overall to convert carbon dioxide back to oxygen during photosynthesis.

These trends have led to larger amounts of carbon dioxide being released into the atmosphere, while the capacity of the earth to recycle the gas has been reduced.

This diagram shows the history of atmospheric carbon dioxide concentrations as directly measured at Mauna Loa, Hawaii. This curve is known as the Keeling curve, and is an essential piece of evidence of the man-made increases in greenhouse gases that are believed to be the cause of global warming. This figure was created by Robert A. Rohde from published data and is incorporated into the Global Warming Art project.

There are also other greenhouse gases that help contribute to the greenhouse effect. These include ozone, methane, nitrous oxide, sulphur hexafluoride, and chlorofluorocarbons.

Methane can also be produced through other processes. For example, it is often found underground within coal deposits. When the coal is mined, methane gas can escape into the atmosphere.

Our domesticated cows also release methane through their bowels. As we increase our herds, more methane gets produced and released.