Causes of climate change

• Milankovitch cycles are variations in the way the earth moves around the sun
• Milankovitch cycles

  Stretch

  • the path of the earths orbit around the sun changes from a circle to an ellipse and back to a circle
  • Every 96,000 years
• Milankovitch cycles

  tilt

  • the earth is tilted at an angle
  • Changes every 41,000 years
• Milankovitch cycles

  Wobble

  • the axis of the earths orbit around wobbles
  • Every 22,000 years
• the Milankovitch cycles affect how far the earth is from the sun, and the angle that the suns rays hit earth

  • this affects how much solar radiation the earth receives
  • these may have caused the glacial and interglacial cycles
• sunspots

  sunspots are cooler areas of the suns surface that are visible as dark patches

  • they increase the suns output of energy
• sunspots come and go in cycles of around 11 years, but larger ones may last hundreds or thousands of years
• periods where there are very few sun sports means solar output is reduced so the earth climate may be cooler in some areas
• most scientists think that changes in solar output dont have a major effect on climate change
• volcanic activity

  1. volcanic eruptions eject large quantities of material into the atmosphere
  2. these particles refleft the suns rays back out into space, cooling the earths surface
• the natural greenhouse effect is essential for keeping out planet warm
• natural greenhouse effect

  1. suns rays hit the earths surface
  2. gases in the atmosphere naturally act like an insulating layer and trap outgoing heat, keeping the earth warm
  3. greenhouse gases that trap heat — carbon dioxide and methane
• human activities are contributing to the greenhouse effect, leading to the enhanced greenhouse effect, which causes global warming
• Farming

  Farming of livestock producing a lot of methane

  Rice paddies contribute to global warming because flooded fields emit methane
• Burning fossil fuels

  Co2 is released into the atmosphere when fossil fuels like coal, oil, natural gas and petrol are burnt
• cement production

  cement is made form limestone which contains carbon, and when cement is produced, it makes co2
• deforestation

  Deforestation means co2 that the plants have taken up is released into the atmosphere when they are burnt