HKDSE Geography/M7/Human Factors in Global Warming

Numerous human factors lead to global warming.

Carbon dioxide

The main greenhouse gas, carbon dioxide is generated in the following situations:

• Burning of fossil fuels: The burning of coal, oil and natural gas
• Burning of petroleum-based fuels by transport: The combustion of fuel for transport, such as aeroplanes and land vehicles
• Forest fires: Forests are important carbon sinks and carbon dioxide is released into the atmosphere by forest fires.
• Incinerators: Carbon dioxide is produced when burning solid waste in incinerators.

Methane

• Livestock rearing: Rearing of livestock, particularly cattle ranching, produces methane.
• Wet rice cultivation
• Decomposition of solid waste in landfills
• Fossil fuel and biofuel combustion also causes methane release

Nitrous oxide

• Use of nitrate fertilisers in arable farming: When nitrate fertilisers are decomposed in soil, nitrous oxide is released.
• Fossil fuel combustion
• Combustion of solid waste in incinerators
• Nylon production

Chlorofluorocarbons (CFCs)

• Air conditioning and refrigeration
• Aerosol sprays
• Cleaning solvents
• Styrofoam