Greenhouse gases such as water vapour, carbon dioxide (CO2), methane, and nitrous oxide (N2O) keep our planet warm. They exist naturally in the atmosphere, heating it by trapping energy that originally came from the Sun. This process is called the greenhouse effect. Without the greenhouse gases, the surface of the Earth would be about -18C, rather than the typical surface temperature of about 15C.
Increasing concentrations of the greenhouse gases trap more terrestrial radiation in the lower atmosphere (troposphere), enhancing the natural greenhouse effect. Over the last 200 years, mankind has increased the amount of greenhouse gases in the atmosphere through processes such as fossil fuel burning. Fossil fuels are made up of carbon and hydrogen, which are changed to water and CO2 when they are burned.
By the end of the 21st century, global average temperatures could be several degrees higher than today. In an effort to reduce or remove the threat of global warming, nations around the world have adopted the Framework Convention on Climate Change. The objectives of this framework are to prevent “dangerous
interference with the climatic system”. The aim is to reduce global greenhouse gas emissions by 5.2% from 1990 levels by 2012.
Renewable and nuclear power are alternative energy resources that do not produce CO2 and may therefore be used to reduce the threat of global warming. As the world aims towards a sustainable energy future, the use of renewables will increase and hence pollution from the burning of fossil fuels will reduce.
Renewable energy refers to power generated by a renewable source. When the energy is generated, the resource is not depleted or used up. They are naturally replenished, and can either be managed so that they last forever, or their supply is so enormous humans can never meaningfully deplete them. Unlike fossil fuels, renewable energy sources do not release carbon dioxide as a by- product into the atmosphere. As the amount of fossil fuel resources on Earth decreases, it is becoming increasingly important to find and utilise alternative fuels.
Examples of renewable resources include:
• wind power;
• solar power;
• hydro-electric power (HEP);
• geothermal energy;
• tidal power and
• wave energy.