Climate change

• Climate change


  A change in the global climate from the expected average
• Global warming


  A gradual increase in temperature attributed to the enhanced greenhouse effect
• Quaternary period


  A period in geological time which stretches from 2.6 million years ago to now
• Natural causes of climate change

  • Solar output e.g. sunspots
  • Changes in Earth's orbit or axis
  • Volcanic activity
• Solar output


  The amount of radiation the sun releases can vary in an 11-year cycle. Increased sun spot activity = higher temperatures
• Earth's orbit


  Moves from circular to oval every 100,000 years. Circular rotation-closer to sun-warmer climate. Oval(elliptical)-further from sun-glacial period(ice ages)
• Volcanic activity


  Large volcanic eruptions emit particles into the atmosphere that block the sun and cool the earth's climate.

  1816 was the year without a summer
• Evidence: Photographs 


  Comparing photos from 1850s with today to show how glaciers have shrunk
• Evidence: Ice cores


  Ice cores are drilled out by scientists who analyse the ancient air

  More GHGs = higher temperatures

  This can go back 450,000 years
• Evidence: Temperature 


  Records using a thermometer show us temperature variations

  Only since 1850s
• Evidence: Tree Rings


  Good growing conditions (warm and wet) means rings are wide.

  Extreme weather (droughts/frost) means rings are thin.

  Trees go back 10,000 years
• Greenhouse Gases (GHGs)


  Three main are carbon dioxide CO2, methane CH4, nitrous oxide N2O
• Human causes of climate change

  Burning fossil fuels to power cars, make electricity and power factories emits CO2.

  Deforestation means trees can’t absorb CO2.

  Agribusiness (large scale intensive farming practices) leads to an increase CH4 from livestock and increase N2O from fertilisers.
• Enhanced greenhouse effect


  The greenhouse effect (GHE) describes heat that is trapped naturally by greenhouse gasses. Humans have made the GHE stronger by emitting more GHGs.

  This is call the Enhanced greenhouse effect.
• Stages of the enhanced greenhouse effect

  1. Sun’s energy enters the atmosphere
  2. Heat is absorbed, trapped, some escapes back to soace
  3. Humans emit GHGs = mean more heat is trapped = temperatures increase = global warming
• LICs more vulnerable: lots of farmers


  Lost food and income due to drought
• LICs more vulnerable: lack of money for defences 


  More damage to buildings from sea levels rise and flooding
• Social impacts

  1)Less rain = droughts = famine more extreme = malnourishment e.g. Yemen (2016-present)

  2)Temperature increase = ice caps melt = seal levels rise = floods = people migrate e.g. Fairbourne, Wales

  3)More extreme weather events(tropical storms)= more homes and businesses flooded
• Environmental impacts

  1. Temperature increase = ice sheets melt = polar habitat impacted e.g. 30% of worlds polar bears could be lost by 2050
  2. Temperature increase = ice sheets melt = sea level rise = flooding of coastal habitats e.g. Fairbourne, Wales
  3. Sea temperatures increase = coral reef bleaching e.g. 25% of world reefs have severe bleaching