Greenhouse gases are the collective chemicals that make up the Earth’s atmosphere that help keep the temperature of the Earth’s surface relatively constant. This is done by maintaining a balance between the sunlight that is reflected from the Earth’s surface and the infrared radiation that is absorbed by the greenhouse gases and trapped in our atmosphere. The process of absorption is what we refer to as the greenhouse effect.
Many gases contribute to the greenhouse effect, some of them are naturally occurring such as water vapour, carbon dioxide, methane, nitrous oxide and ozone. Others are exclusively man-made such as chemicals from aerosols.
The Carbon Cycle
Levels of carbon dioxide in the atmosphere are controlled in nature by a process known as the “carbon cycle”. The movement of carbon is controlled between the air, land and water by natural processes such as photosynthesis, respiration and decay. While natural processes can handle some of the anthropogenic (caused by humans) carbon dioxide emissions produced each year, there is an estimated 3.2 billion metric tons added to the atmosphere annually. It’s this growing imbalance between emissions and absorption that is attributed to the increase in greenhouse gases in the atmosphere.
Carbon Dioxide
Carbon Dioxide is the most prominent greenhouse gas in the Earth’s atmosphere. It has been made even more abundant through the human process of removing the naturally occurring carbon from the earth in the form of coal, oil and natural gas, and burning it for fuel, releasing it into the atmosphere in incredible quantities.
When we talk about anthropogenic carbon emissions we are referring to such things as burning fossil fuels (coal, oil, natural gas) and clearing of forests which removes large swathes of potential sources of photosynthesis…and human exhalation. At a time when it is becoming increasingly imperative that we reduce our carbon emissions, the evidence points to the fact that they are still increasing.
Methane
Another greenhouse gas that is contributing to the problem of global warming is methane. High levels of methane are produced from landfills when open dumps and waste decomposes under anaerobic conditions. It is also released as part of the coal mining process when trapped methane is released into the atmosphere. Significant amounts of methane are also naturally produced by livestock as part of their digestive system. Rice cultivation produces quite high levels of methane due to the flooding process which promotes anaerobic decomposition or organic matter in the soil.
Each year around 350-500 million tons of methane from human related activities are released into the atmosphere adding to the greenhouse gases. The problem lies in the fact that methane is 20 times effective at trapping in heat than carbon dioxide.
Nitrous Oxide
Better known to most people as laughing gas, this is the stuff that we use as an anaesthetic but it’s a naturally occurring gas and one of our greenhouse gases. It is released naturally from the ocean and by bacteria in the soil. Humans add up to 15 million tons into the atmosphere through nitrogen-based fertilizers, sewerage treatment and car exhausts. Nitrous oxide emissions need to be reduced because it stays trapped in the Earth’s atmosphere for a long time.
Greenhouse Gases and Global Warming
Future carbon dioxide levels are expected to continue to rise due to fossil fuel emissions and destructive land use changes. Possibly one of the saving graces will be the limited availability of fossil fuels but until then it’s up to us to change our pattern of daily energy consumption and look to alternative energy sources, changed transport patterns and more responsible land use practices.
I'll be revealing my own plans for how I will be reducing my impact on greenhouse gases over the coming months. I intend to track the size of my carbon footprint and will try to cut it in half so stay on the lookout for a regular series of posts that will regularly update my progress.
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