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What is causing Global warming?
There are six major causes of the global warming that we are currently seeing.
- Water vapour and feedback
Water vapour accounts for between 70% and 95% of global warming. Water vapour absorbs and then emits infrared radiation in Earth's atmosphere, this increases the earths temperature.
Feedback results from the evaporation of water in the oceans, on the planets surface and in the atmosphere. As the water vapour absorbs radiation fro the sun and the earth its temperature increases thus causing more evaporation. Additional carbon dioxide in the atmosphere also contributes to this effect. This loop continues until the levels of water vapour reach a point of equilibrium. This has a far greater effect on global warming than CO2 on its own.
- Energy use and production
The running of electrical appliances, diving vehicles, preparing and cooking food as well as using heating and cooling systems all contribute to the consumption of energy. Predominantly this energy is the result of burning certain kinds of fossil fuels. The burning of oil, coal and gas releases carbon dioxide into the atmosphere. Carbon dioxide is one of several greenhouse gases and is in fact considered to be the main contributory greenhouse gas as far as global warming is concerned. Althougth there are several therories concerning the climate changes we are seeing, there is a general agreement among scientists that increased carbon dioxide in the atmosphere is increasing the earths natural greenhouse effect and that is what is known as global warming. Between 50% and 75% of all our carbon dioxide emmissions can be attributed to our energy use.
The global transport market is the fastest growing energy-consumption sector in the world. Approximately 20 % of all man made emissions of carbon dioxide come from the exhausts of cars and motorcyles. The emissions of carbon dioxide from an average car can roughly be considerd to weigh the same as that car.
- Chlorofluorocarbons
Chlorofluorocarbons also known as CFCs, are chemical compands that contain chlorine and bromine. They are often associated with the rapid depletion of the ozone layer which protects the earth from harmful rays. These CFC substances were discovered and then develpoed for use in the early 1930s and subsequently have been used in numerous household and business applications. Because they are stable and relatively unreactive as well as being non-toxic and non-flammable they are ideally suited for use as coolants, solvants, blowing agents and propellants.
It was discovered in 1973 that chlorine was a contributory factor to ozone destruction. This catalytic destruction of ozone meant that the ozone layer was effectively being eaten away. However even though this process was known it was not considered a problem until the early to mid 80s. Once the discovery of the damage to the ozone layer over the polar ice caps was announced many initiatives were started in order to discover the extent of the problem and to learn more about the ozone depletion processes, along with calls to freeze or diminish production of chlorinated fluorocarbons.
- Agricultural practices
Approximately 90% of agricultural energy use can be put down to the development of nitrogen fertiliser, farm machinery and pumped irrigation. Theses processes are also a integral part of todays agriculture.
Land conversion produces almost half a million tonnes of nitrous oxide a year, this increases the amount of nitrogen in the amosphere. Although nitrous oxide is a far more potent greenhouse gas than carbon dioxide it is currently at a far lower concentration that carbon dioxide. The application of 70 million tonnes a year of nitrogen to crops via fertilizers is thought to be respomsible for 10% of the total annual nitrous oxide emissions of 22 million tonnes. In around 30 years time this may have increased two fold.
Methane is also a contributory greenhouse gas, emissions of which are increasing all the time. Livestock fed on a high protein diet produce far more methane than animals fed on grass. The action that fertilizers have on decreasing methane uptake in soil also contributes to the methane problem. The final element to the methane problem is the use of nitrogen fertilized rice paddies as opposed to traditional rain fed paddies.
- Changes in land use
Essentially land usage is changing in two ways: human-caused and naturally occuring or indirect causes. Human causes include (but are not limited to) deforestation, reforestation and afforestation, agriculture, and urbanization. Naturally occuring changes are caused and affected by carbon dioxide concentrations such that they force changes in vegetation. Worldwide, it is thought that these kind of land use changes contribute to round 18% of emissions.
- Other industrial activities
These include all manufacturing and distribution processes as well as the service industry. Essentially all idustrial activities use energy and it is our reliance on fossil fuels for energy that is the major contributor to global warming.
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