Transcript How Human Activity Affects Greenhouse Gases

How Human Activity Affects
Greenhouse Gases
What are Greenhouse Gases
Any gas that has three or more atoms
in its structure will act as a greenhouse
gas
Examples - CO2, H2O, CFC, CH4, but
not O2 or N2
Deforestation/burning of fossil
fuels
Both affect carbon dioxide levels
CO2 contributes most to the greenhouse
effect because of its quantity.
CFC’s are a 100,000 times more effective
as a greenhouse gas but theirquanitiy is
very low in comparison to CO2
Deforestation/burning of fossil
fuels
Carbon Cycle – sinks/reservoirs –
oceans
Vegetation e.g. trees
Carbonate rocks e.g. limestone /chalk
Soils
Atmosphere
Fossil fuels (coal, oil, Natural gas)
Major CO2 Releases
Burning coal, oil, gas
Deforestation
Burn trees
Release CO2
Reduction of trees which absorb CO2
during photosynthesis
Major CO2 Releases
Motor vehicles exhausts
Produce CO2
Add 7 million tons every year to the
atmosphere
Major CO2 Releases
2/3 – Burning Fossil Fuels
1/3 – Deforestation
CO2 causes 50% of global warming
Cattle farming/Rice fields
Methane
Produced by anaerobic bacteria
Found in bogs, swamps, marshes,
paddy (rice) fields
Digestive systems of cows, sheep, and
camels
Methane
1.7ppm
Compared to CO2 ~400ppm
Accounts for 15% of global warming
25 times better than CO2 at absorbing
infra red radiation
Increasing at a rate of 1% per year
Major contributor = India (cows)
Nitrous oxide -NOx
Burning fossil fuel
Denitrifying bacteria can
convert nitrate fertilizers
to nitrous oxides.
Nitrogen Cycle
Accounts for 6 % global
warming/greenhouse
effect
CFC’s - Chlorofluorocarbans
Sources
Propellants in aerosol cans
Coolants in refrigerator
Expanders in plastic insulating foam
CFC’s Account for 22% of global
warming
Montreal protocol
CFC’s banned but very long “residence
time”
Water Vapor
Very important greenhouse gas but not
significantly affected by man