E3 Greenhouse Effect

E.3.1 Describe the greenhouse effect.

The Greenhouse Effect is the trapping of heat in the atmosphere. Short wavelength sunlight (visible light and UV) penetrates the atmosphere to warm the Earth's surface which partially absorbs the energy before radiating it back out as longer wavelength radiation (infrared). This long-wavelength radiation is partially retained in the atmosphere and only some is re-emitted back out.

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Greenhouse gases, like carbon dioxide, methane, CFCs, water vapour and nitrous oxides, trap as a one-way filter, trapping heat like in a glass/plastic in a greenhouse. This heating effect is necessary for the maintanence of life on Earth and is what maintains global temperatures. However, with increased concentrations of greenhouse gases, the greenhouse effect is 'enhanced', with even more radiation being trapped in the atmosphere, causing a significant rise in global temperatures known as global warming. The rate of temperature change is significantly faster than any observed in the last 10000 years.

E.3.2 List the main greenhouse gases and their sources, and discuss their relative effects.

Water vapour: main source is the evaporation of water bodies and the combustion of hydrocarbons. Occupy 0-4% of the atmostphere, and

E.3.3 Discuss the influence of increasing amounts of greenhouse gases on the atmosphere.

Over the last century worldwide:

1. Increase in temperatures by 0.5ºC

2. 1% increase in precipitation

3. 15-20cm rise in sea levels from glacial meltdown and expansion of ocean water by warmer temperatures.

--> Particularly in the Arctic, global warming from rising levels of carbon dioxide is particularly irreversible because of how the melting of permafrost results in further decomposition of the previously frozen matter, causing a continual increase in carbon dioxide and methane levels.

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Scientific models are also being exceeded- the prediction of scientific models are taking place 30 years sooner than expected.

IMPACT OF CLIMATE CHANGE ON HEALTH, AGRICULTURE, FORESTS, WATER RESOURCES, COASTAL AREAS, SPECIES DIVERSITY, SPECIES NUMBERS AND NATURAL AREAS:

-Health
Life cycles of pathogens and insects affected (e.g. Mosquitoes). Water-borne diseases may become more prevalent.
-Agriculture
Crop yield and crop distribution will be affected. Flooding of land from sea water may result in salination of the water table and affect crops requiring fresh water.

-Forests
Insects and diseases may increase, summer droughts may produce forest fires, higher temperatures and higher increased precipitation may cause increase in vegetation growth, but plants requiring little rainfall may become extinct.

-Water Resources
Decreased water quality due to flooding, more resources needed to turn water into potable sources. Both floods and droughts are more likely, from increased precipitation and increased rates of evaporation.

-Coastal Areas
Eroding of beaches, flooding of low lands and coastal flooding, and resulting loss of such ecosystems.

-Species and Natural Areas
Loss of cold water fish habitat, shift in ecological areas (organisms in temperate regions may migrate upwards to previous uninhabitable regions). Desertification. Loss of habitats and species.