1. Greenhouse Gases and Climate Change

2. Natural Greenhouse Effect
Most solar energy from the sun is absorbed by the surface of the Earth & warming it up.
Solar energy is also reflected or re-emitted into the atmosphere as infrared radiation.
Infrared radiation acts as a “insulating blanket” as it is thermal energy trapped in the atmosphere. This helps warm up the Earth. This process is called the natural greenhouse effect.

3. Greenhouse Gases
Greenhouse gases (GHGs) are substances that trap (absorb) heat energy.
The natural greenhouse effect is possible due to the roles played by the following greenhouse gases (examples given are natural sources):
Water vapour (H2O) – water cycle
Carbon dioxide (CO2) – carbon cycle, oceans, respiration, decomposition, volcanic eruptions
Nitrous oxide (N2O) – nitrogen cycle
Methane (CH4) – livestock, wetlands (decomposition), volcanic eruptions
Ozone (O3) – atmospheric component (absorbs dangerous UV radiation, yay for us!)

4. Anthropogenic Greenhouse Gases
The Earth's climate changes through natural processes (natural greenhouse effect), but also as a result of our society's GHG emissions.
Human-directed activities: “anthropogenic”
Anthropogenic GHGs
CO2
Methane
Nitrous oxide
CFCs

5. GHG: Carbon Dioxide
Half of the CO2 released into the atmosphere due to anthropogenic sources
Burning of fossil fuels (coal, oil, diesel, natural gas) for energy and transportation
Deforestation
Industrial activities (eg. Cement making, metal processing)

6. GHG: Methane
34x more potent than CO2 (in terms of how effectively it absorbs heat)
Livestock “emissions” (ruminants)
Wetlands
Landfills
Decomposition of organic matter by bacteria
Coal-mining
Rice paddies
Underground reservoirs = industrial access (eg. Pumping oil)

7. GHG: Nitrous Oxide Nitrogen fertilizers
Burning of fossil fuels (eg. Motor vehicles primary source of N2O emissions)
Industrial processes
Nitrogen cycle (typically bacteria breaking down nitrogen in soils and oceans)

8. GHG: Chloroflurocarbons (CFCs)
No natural sources
Refrigerant coolants
Air conditioners
Aerosol propellants
Ozone layer depletion due to chemical reactions between O3 and chlorine atoms.
Montreal Protocol (1987) to protect ozone layer and banning of CFCs

9. Sinks and Sources Source: Release GHG into the atmosphere
Sink: Remove GHG from the atmosphere
Examples of Sinks:
CO2 sinks: plants & phytoplankton (in oceans) for photosynthesis; ocean dissolution
H2O sinks: condensation & precipitation
Methane sinks: atmospheric reactions

10. GHGs: How does it affect us?
The natural greenhouse effect keeps the Earth at a good temperature (15°C instead of -18°C)
↑ emissions of greenhouse gases (esp. anthropogenic sources) means that more heat energy will be trapped in the atmosphere, therefore ↑ average temperature of Earth.
More extremely hot days
Health concerns with population groups (elderly, children, etc)
More intense weather
Changes in transportation systems (eg. Airline, sea, land)
Water quality
Fisheries & related industries and coastal communities
↓ Crop yields (economic impacts)
↑ irrigation of agriculture lands
↑ in warm-climate infectious diseases (eg. Malaria)
↓ Wildlife reproduction (including endangered species) and ecosystem impacts
EVERYTHING!