Causes And Effects Of Global Warming

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Causes And Effects Of Global Warming

• IB SL

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Global Warming

• First emerged as a cause of global concern in the
  1980's, a result of the apparent rise in global
  temperatures, believed to be due to human
  activities, such as burning of fossil fuels and
  destruction of forests.
• There is debate as to whether global warming
  exists, as it could merely be another example of
  changes in temperature the world has seen over
  millions of years.
• It is important to distinguish global warming
  from the greenhouse effect.
• The greenhouse effect is a naturally occurring
  phenomenon, without which human life would not
  exist on the earth.

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Greenhouse Effect
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Greenhouse Gases And Radiation

• Many greenhouses gases exist naturally, and it is
  human actions that are increasing their
  concentrations within the lower atmosphere.
• It is believed that as the amount of greenhouse
  gases in the atmosphere increases, the amount of
  long-wave (infra-red) radiation in the lower
  atmosphere also increases, thus raising
  temperatures.

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Causes Of Global Warming
Gas Source Use Way It Increases Global Warming
Water Vapour Oceans, lakes, rivers, reservoirs. Humans have little impact upon levels. Absorbs limited outgoing radiation. Water vapour and clouds are responsible for nearly 98 of the natural greenhouse effect.
Carbon Dioxide Burning of fossil fuels, and forests, breathing animals, less produced by southern hemisphere (less land). Absorption of long wave radiation. Approximately 50.
Methane (CH4) Much from break down of organic matter by bacteria (rice paddy fields) cows, swamps marshes. As above. Approximately 18.
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Causes Of Global Warming
Gas Source Use Way It Increases Global Warming
Ozone Naturally from some oxygen atoms. Ozone in the troposphere is due to chemical reactions between sunlight and agents of pollution. Filters short wave UV radiation. Difficult to estimate.
CFCs Fridges and aerosols. 25, but increasing due to ability to survive within the atmosphere for 100 years.
Nitrous Oxide Nitrate fertilisers, transport and power stations (combustion). Absorption of long wave radiation. Approximately 6.
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Positive And Negative Effects
Impact on Effect Consequence (-) Consequence ()
Health Malaria and cholera increase, due to temperature increase. More money needed to fight disease, strain on medical services, rise in death rate.
Vegetation Shifting flora and fauna to different areas. Extinction of some species. Spread of pests and disease, alteration in crop yields, may increase food shortages. Canadian Prairies could become major wheat growing belt. Areas able to grow different crops, for example, citrus fruits in the UK.
Weather More extreme climates in inland locations. More frequent and devastating hurricanes. Unknown at present. Unknown at present.
Ocean Sea temperatures increase, sea levels rise, shift in ocean currents. Changes in number of fish stocks and their location will impact the fish industry. Increase in fish stocks in certain areas.
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Positive And Negative Effects
Impact on Effect Consequence (-) Consequence ()
Landscape Reduced snow cover in some areas. Glaciers melt in Antarctica. Rise in sea levels. Extended summer season in some landscapes due to higher temperatures, increasing revenue.
Hydrology Reduction of wetland areas, as precipitation is reduced. In some places river flooding may increase. Great pressure on water supplies. Problems for HEP schemes and irrigation. Increased awareness of water conservation measures, less water wastage.
Population Reduction of areas suitable for human habitation, for example. lowland Bangladesh. Increased population densities increase possibility of disease and malnutrition. Forced movement of population from densely populated coastal areas, to interior locations.
Climate Location of jet stream may alter. Depressions may shift south, causing them to be more intense. Better forecasting needed to warn people of approaching storms. Insurance premiums will increase. More accurate weather forecasting developed
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Activity

• Look at the Global Warming Statements W/S and
  sort the statements into 3 categories using 3
  different colours...
• Basic facts about Global Warming.
• Causes of Global Warming.
• Effects of Global Warming.
• Strategies to reduce Global Warming.