1. The Enhanced Greenhouse Effect

2. The Enhanced Greenhouse Effect:
The natural greenhouse effect has been enhanced by human activities, which contribute to the emissions of greenhouse gases

3. Greenhouse Effect
With the greenhouse effect the earths surface temperature, 15°C, is approximately 30°C warmer
The process by which infrared and near infrared (visible) radiation warms the earth atmosphere
Near infrared (visible) warms the surface
Infrared warms the atmosphere
Oxygen (O2), nitrogen (N2), and argon (Ar), which make the majority of the atmosphere, do not react significantly with the radiation.
Methane, ozone, carbon dioxide, water vapour most significant greenhouse gases
more gases = heated atmosphere = more evaporation and clouds = more absorption of radiation = heated atmosphere
The earth reflects 30% of the radiation while 70% are absorbed
Other greenhouse gases: nitrous oxide, sulphur hexafluoride, hydro fluorocarbons, per fluorocarbons, chlorofluorocarbons

5. Methane is one of the most potent greenhouse gases
Causes 4-9% of greenhouse effect
tundra of Siberia is beginning to melt.
ice is a form of methane clathrate, ice with large amounts of methane in the crystal structure
if melted methane gas will be released into the atmosphere.
Methane clathrate deposits are also with in ocean beds
depths of +300m where the water temperature will be approximately 2°C.
If the ocean temperature rises, methane clathrate deposits will release methane gas in to the ocean drastically influencing environment change.
Predicted that 5°C rise would be enough to create extreme changes in marine life.
1ton of methane = 25tons of carbon dioxide in atmosphere

6. Carbon Dioxide (CO2)
Naturally present in the atmosphere in large amounts
Earths atmosphere: 5.14 x 1018 kg
CO2 in atmosphere: 3.0 x 1015 kg
Expected to rise at an unknown rate due to continuing burning of fossil fuels
Causes 9-26% of greenhouse effect
Oceans absorb approximately one third of all CO2 emissions; they act as a huge carbon sink. But as the water temperature rises, CO2 will be released into the atmosphere to react with radiation from the sun.
Warms rapidly in sunlight

7. Ozone Causes 3-7% of greenhouse effect
Created when UV rays react with oxygen in the stratosphere
Essential as it filters harmful UV rays
Haloalkanes, such as methane, reduce the amount of ozone in the stratosphere
Allows for UV rays to reach the troposphere (where most of the oxygen is) causing the creation of ozone
A major constituent of smog

8. Water Vapour Causes 36-70% of greenhouse effect
Increase in atmospheric temperature will increase the evaporation of water
Results in increasing infrared abortion and increased heat
The result of having more water vapour in the atmosphere (troposphere mainly) would theoretically mean that there would be more clouds and thus more radiation reflected back to earth
Theoretical because it is unsure if there actually would be more clouds or if the amount of clouds would be reduced

9. Natural Greenhouse Emissions
Volcanoes
Oceans
Coal combustions
Petroleum combustions
Natural gas combustions

10. Human Impact on the Greenhouse Effect
From the end of the last Ice Age until the end of the 18th century, the levels of greenhouse gases in the atmosphere remained fairly constant
Since the Industrial Revolution, humans have released extra quantities of greenhouse gases into the atmosphere, enhancing the natural greenhouse effect
The enhanced greenhouse effect is the direct result of human activities
Upsetting the precisely balanced natural systems

11. Human Activities Removing and burning vegetation Burning fossil fuels
Forest build up store of carbon in trees, soil, and fallen leaves
When land is cleared, much is rapidly converted back to carbon dioxide
Burning fossil fuels
Coal, oil, and natural gas contribute to carbon emissions
Energy for industrial processes, transportation, agriculture, heating, lighting, etc …

12. Waste breakdown Agriculture
Decaying organic material dumped in landfills create carbon dioxide and methane
Agriculture
Animals produce methane through digestion
Fertilizers release nitrous oxide
Rice production in paddy fields generates methane

13. Gases Contributing to the Greenhouse Effect
Chlorofluorocarbon (CFC) are produced by aerosols, refrigerators and air conditioners. They are harmful to the Biosphere because they are destroying the Ozone Layer.
Hydrochlorofluorocarbon: a fluorocarbon that is replacing chlorofluorocarbon as a refrigerant and propellant in aerosol cans. Less impact on ozone.

14. Consequences for Global Warming
Increasing concentrations of greenhouse gases will prevent more heat from escaping, increasing the world’s average temperatures
Causing global warming and changes in climate
Effecting cloud cover, precipitation, wind patterns, duration of seasons, changes in ocean currents, etc …

15. Changes in weather patterns will lead to:
Droughts
Heavy precipitation (floods)
Declining snow cover and glaciers (contributing to rises in sea levels)
Increase in frequency and intensity of tropical cyclones