Difficulty: Summiteer (Level 3)
Carbon dioxide, or CO2, is the best-known greenhouse gas. But several others are also changing the Earth’s climate.
Methane (CH4) is the second most important greenhouse gas linked to human activity after CO2. About 40 per cent of methane comes from natural sources, such as wetlands. But the majority is related to human activities such as agriculture, fossil fuels and waste. Reducing methane emissions would help to slow global warming.
Nitrous oxide (N2O) is the third major greenhouse gas. It is almost 300 times more dangerous than carbon dioxide. It is mainly emitted by man-made nitrogen fertilisers and manure used in agriculture.
Fluorinated greenhouse gases include PFCs, HFCs and SF6. These are found in fridges and freezers, heat pumps, air conditioners and electrical networks. Even in small quantities, they have a high capacity for warming the Earth.
CFCs are another ozone-depleting fluorinated gas. The Montreal Protocol has already lowered the presence of CFCs in the atmosphere. The protocol was signed in 1987 and has been ratified by 195 countries.
Answer: agriculture, fossil fuels and waste
