Changing Climate

Past climate change
1. Causes
  1. Orbital theory
    1. Earth's orbit changes every 100,000 years
  2. Sunspot theory
    1. Sunspots show more active areas of the sun
    2. Solar output changes every 11 years
  3. Asteroid theory
    1. Extremely large asteroids blast large amounts of dust into the atmosphere
    2. Dust blocks out sunlight and cools the Earth
  4. Eruption theory
    1. Volcanic eruptions spread large amounts of ash into the stratosphere
    2. Ash blocks out the sunlight
  5. Ocean current
    1. Changes can cause warming and cooling
2. Measurements
  1. Ice cores
    1. Cylinders of ice drilled from glaciers - up to 500,000 years old
    2. Indicates carbon dioxide levels in the atmosphere at the time
  2. Glacial period
    1. A cold period of the Earth when it is covered with ice
  3. Interglacial period
    1. A warm period of the Earth, like the one we're in now
Impacts of climate change
1. People (The Little Ice Age)
  1. The Little Ice Age was a cold period in northern Europe, lasting form the 15th century to the mid 19th century
    1. Long cold winters and short summers
  2. Europe
    1. Low crop yields - caused the great famine
      1. New crops, like potatoes, were grown
      2. 10-20% of peasant farmers died of hunger
    2. 'Frost fairs' held on the Thames
    3. Glaciers in the alps crushed villages
  3. Viking Greenland
    1. Sea ice prevented trade between Greenland and Iceland
    2. Cattle died due to lack of food
    3. Resources ran short
2. Animals
  1. Megafauna - giant animals which evolved during the ice age
    1. Mammoths, sabre-toothed tigers etc.
    2. When the ice age ended, temperatures rose 5ºC in 10,000 years
      1. Megafauna could not adapt, so became extinct
    3. Hunting could have also contributed to their extinction
Case studies
1. UK
  1. Current climate
    1. Mild and wet
    2. Prevailing wind from Atlantic Ocean - brings moisture
    3. Warm North Atlantic current keeps the UK relatively warm
  2. Future climate change
    1. Temperature rise
    2. Longer summers, colder winters
    3. Drier summers and unpredictable rainfall
  3. Environmental impacts
    1. Severe storms and longer droughts
      1. Leads to famine and disasters
    2. More coastal erosion and flooding
      1. People lose their homes due to rising sea level
    3. Changes to fishing industries
    4. Disrupted ecosystems
      1. Species cannot adapt
    5. Warmer temperatures could encourage diseases like malaria
  4. Economic impacts
    1. Increase in refugees
    2. Farmers have more crops and longer growing seasons
    3. More people have holidays in the UK
    4. Flood damage/protection costs
    5. Altered housing design
2. Bangladesh
  1. Environmental impacts
    1. River flooding would become worse due to heavy rainfall
    2. Tropical storms become more frequent and damaging
    3. Dry season becomes longer
  2. Economic impacts
    1. Could damage agricultural output
    2. Property damage
    3. Cost of flood damages/management
    4. Water-borne diseases will be spread
    5. Damages aquaculture
Present & future climate change
1. Human activity causes emission of greenhouse gases such as carbon dioxide and methane
  1. This has been occurring since the industrial revolution
  2. More carbon dioxide is produced because of increased industry, need for energy, transport and deforestation
2. Carbon dioxide levels - at their highest for 650,000 years
3. Methane levels - at their highest for 900,000 years

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Changing Climate

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