02 1.1 Definition
Global warming is the continuous rise in the temperature of the air adjacent to the Earth's surface.
- It results mainly from the burning of fossil fuels (coal, oil, natural gas), which emits greenhouse gases that act like a blanket around the Earth, trapping heat in the atmosphere and raising its temperature.
- Climate change is the broader long-term change in climate patterns (temperature, rainfall, storms) that results.
The greenhouse gases that cause global warming (as listed in the book): carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), chlorofluorocarbon compounds (CFCs) and water vapour.
1CO₂
Main sources
- burning of coal, oil and gas; cement making; deforestation
Notes
- the main contributor to the enhanced greenhouse effect; stays in the air for centuries
2CH₄
Main sources
- rice fields, cattle, landfills, natural-gas leaks, wetlands
Notes
- per molecule about 28 times as strong as CO₂ over 100 years
3N₂O
Main sources
- fertilisers, industrial processes, burning
Notes
- about 265 times as strong as CO₂
4CFCs
Main sources
- refrigerants, aerosols (banned by Montreal Protocol)
Notes
- thousands of times as strong; also deplete ozone
5Water vapour
Main sources
- evaporation
Notes
- amplifies warming caused by other gases
(The book's multiple-choice exercise treats ozone as not belonging to this list; ground-level ozone is also a weak greenhouse gas, but the book's list is the one to use in answers.)