A topic on everyone’s mind of late is the carbon tax. With seemingly endless media coverage and ongoing debate about the tax, it is easy to forget about why it’s all happening. We think it’s a perfect time to brush up on the less contentious facts of greenhouse gas emissions.
The most common greenhouse gases
Greenhouse gases (GHGs) are gases in the atmosphere that absorb heat radiated by the sun or reflected off the earth. There are many greenhouse gases in the atmosphere. The most abundant (in order) are water vapour, carbon dioxide, methane and nitrous oxide.
The source of greenhouse emissions
There are several natural and anthropogenic sources of greenhouse gases. Water vapour enters the atmosphere through evaporation. Carbon dioxide is released into the atmosphere through processes involved in the carbon cycle (such as the decay of dead vegetation or volcanic activity). Methane gas is released by animals and nitrous oxide is produced by microbes in soils.
Humans can contribute to the release of these gases by indirectly accelerating the natural release of GHGs. For example, increased agriculture (especially cattle) can lead to more methane production. Deforestation can also effect the concentration of GHGs in the atmosphere as trees are a carbon dioxide “sink”, that is, they remove carbon dioxide from the atmosphere. A decrease in carbon sinks means that more carbon is left in the atmosphere.
GHGs are also directly released into the atmosphere by human activity, particularly the burning of fossil fuels. Fossil fuels contain a high percentages of carbon and when burned, are released into the atmosphere as carbon dioxide and other gases. Humans burn fossil fuels in the form of coal, petroleum and natural gas.
Greenhouse gases and ‘global warming’
Greenhouse gases warm the planet (the greenhouse effect). This in itself is needed, as the warmth of our atmosphere is what has allowed life on earth to survive. However, many believe the increase in greenhouse gas emissions (particularly after industrialisation) is leading to a warming of the planet. Many also believe that this will have dire consequences for the earth’s ecosystems, climate and our way of life.
All that re-capped in a 3 minute video
Here’s a great three-minute video from the University of New South Wales on the topic:
Australia’s key role in measuring global emissions
Atmospheric composition is measured at three key ‘baseline’ stations around the world. One of these is located in Cape Grim on Tasmania’s west coast. The baseline stations measure air samples that represent a large area that is unaffected by pollution from nearby cities or industry. In Tasmania, the baseline air comes from the Southern Ocean. Air samples are taken then tested for pollutants and greenhouse gases with each greenhouse gas requiring its own specific test.
Here is the data from the last 30 odd years of measuring carbon dioxide emissions at Cape Grim:
- Alegria Alano
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