5.2 The Greenhouse Effect
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The document discusses the greenhouse effect and its impacts. It provides background on the carbon cycle and increasing levels of carbon dioxide measured since 1958. The greenhouse effect creates moderate temperatures by trapping heat, while the enhanced greenhouse effect from human emissions may cause climate change. Scientists cannot agree on exact impacts but they could include increased droughts, flooding, food shortages, disease, and loss of biodiversity. The Arctic is especially vulnerable, as melting permafrost releases methane and species struggle with habitat changes.
5.2 The Greenhouse Effect
- 1. 5.2: The Greenhouse Effect Topic 5: Ecology & Evolution Miss Friedman
- 2. 5.2.1: The Carbon Cycle Carbon is one of the 4 main elements found in all organic molecules including carbohydrates, lipids and proteins Carbon is found in one of four “pools” Biosphere Oceans Atmosphere Sediments
- 3. 5.2.1: The carbon cycle Carbon is moved between these four pools by a variety of biological, geochemical & industrial processes Photosynthesis Respiration Feeding Fossilization Combustion
- 5. 5.2.2: Historical Records Trends in atmospheric gases are studied as indicators of potential climate change Carbon dioxide has been monitored at Mauna Ioa atmospheric laboratory on Hawaii since 1958 The basic trend is an increase in atmospheric carbon dioxide levels
- 6. Carbon dioxide concentration has increase since 1960 from around 315 ppm to 380 ppm Graph is not smooth but goes up and down to reflect changes in the amount of atmospheric carbon dioxide due to the seasons Autumn leaves drop & plants no longer take up CO 2 Spring when plants start to photosynthesize CO 2 levels drop
- 7. 5.2.3: Atmospheric gases & enhanced greenhouse effect Greenhouse effect A natural process that creates moderate temperatures on earth to which life has adapted. Earth is about 30 o C warmer than it would be without any greenhouse gases in the environment. This is needed to sustain life on earth.
- 8. 5.2.3: continued Enhanced greenhouse effect The concern that the activities of humans may be increasing the levels of carbon dioxide and other greenhouse gases (methane, oxides of nitrogen) in the atmosphere. This may lead to increased global temperatures and climate change.
- 9. Increase in carbon dioxide and other greenhouse gases will increase particles in atmosphere More infra-red will be absorbed, scattered and retained as heat Average global temperature will rise
- 10. 5.2.4: The precautionary principle The concept that someone wishing to take a certain kind of action should prove that the action does not cause serious or irreversible harm to the public if there is no scientific consensus about the outcome of the action. Both the European Union and the United Nations have adopted the principle as a foundation for some policies Montreal protocol (1987) Rio Declaration (1992) Maastricht Treaty (1993)
- 11. 5.2.4: continued Read the article http://en.wikipedia.org/wiki/Precautionary_principle Read the Policy document from the UK Heath and Safety Executive http://www.hse.gov.uk/aboutus/meetings/committees/ilgra/pppa.htm Read the TOK link in your textbook pg. 82
- 12. 5.2.5: Precautionary principle & the greenhouse effect Since scientist cannot agree on the exact effects of increasing levels of carbon dioxide, the precautionary principle should be applied Countries could agree to reduce greenhouse emissions and boycott trade with countries that do not comply However, in poor countries it may not be possible to reduce greenhouse emissions without delaying economic growth
- 13. 5.2.5: continued Why can’t scientist know what problems the Greenhouse effect will cause? Climate is a complex phenomena with many emergent properties often based on time frames beyond the human experience. This makes predictions of location and timing difficult.
- 14. 5.2.5: continued However, it is possible to hypothesize about the general effects: Increased frequency and intensity of droughts Flooding as a result of higher rainfalls, increased snowmelts and rising sea levels Decline in food production Increased disease (pathogens survive better in colder temperatures) More extreme weather Loss of biodiversity
- 15. 5.2.6: Greenhouse effect & the artic ecosystem As global temperatures rise, many ecosystems would be affected but the artic ecosystem would show clearly visible changes The average artic region temperature is rising at twice the speed of the rest of the world
- 16. Negative Effects Melting permafrost in Siberia would release more methane (a greenhouse gas) Species, like caribou, polar bears, seals, are changing their migration pattern to respond in changes to their feeding patterns Native people are finding it harder to hunt Villages move as environment becomes a swamp due to permafrost disappearing Polar bears hibernate less as temperature rises. Must swim further and more often to reach prey/destination which uses more energy Biodiversity could change and herbivore animals would need to change their eating patterns
- 17. Positive Effects Milder climate would enable other species to survive in Artic (though competition could lead to extinction of other plant species) Plant productivity would increase biodiversity in the area