Climate change

• CAUSES NATURAL - orbital changes

  • the way the earth moves around the sun changes. These changes affect the amount of solar radiation (how much energy) the earth receives
  • if the earth revives more energy (by solar radiation) it gets warmer
  • orbital changes may have caused the glacial and inter glacial cycles of the Quaternary period
• CAUSES NATURAL - volcanic activity:

  • when a volcano erupts it produces lots of ash which blocks out the sun so the earth surface cools this is called volcanic winter
  • volcanoes release CO2 (a greenhouse gas) but not enough to cause warming
  • volcanic activity may cause short - term changes in climate e.g. the earth cooled after Mount Pinatubo erupted in 1991
• CAUSES NATURAL - solar output

  • suns output in energy isnt constant it changes in short cycles of about 11 years and possible cycles hundreds years long as well
  • high output - increase earth temperature
  • reduced output - decrease earth temperature
  • solar output isnt thought to have a major effect on climate change
• CAUSES HUMAN - burning fossil fuels

  • CO2 is released into the atmosphere when fossil fuels (coal, gas, oil and petrol) are burnt eg cars
• CAUSES HUMAN - farming

  • farming of live stock produces lots of methane eg cows
  • rice paddies contribute to global warming because flooded fields emit methane (blocking oxygen from the soil so bacteria multiply which releases methane)
• CAUSES HUMAN- cement production

  • cement is made from limestone, which contains carbon, when cement is produced lots of CO2 is released into the atmosphere
• CAUSES HUMAN - deforestation

  • plants remove CO2 from the atmosphere and convert it into organic matter using photosynthesis.
  • when trees are cut down they stop taking CO2
  • CO2 is also released into the atmosphere when trees are burnt as fuel