climate change

• Global warming


  The sharp rise in global temperature over the last century
• Climate change


  Any significant change in the earth's climate over a long period
• Many people confuse the two terms global warming and climate change
• The most recent geological time period spanning from about 2.6 million years ago to right now


  Quaternary period
• In the period before, the earth was much warmer and stable before it entered a cold glacial period lasting 100,000 years
• Evidence for climate change

  • Ice and sediment cores
  • Tree rings
  • Pollen analysis
  • Temperature records since the 1850s
• Ice and sediment cores

  • Scientists drill into ice sheets to get long cores of ice, and by analyzing the gases trapped in the layers of ice they can tell what the temperature was each and every year
• Tree rings


  • As a tree grows it forms a new ring each year, the thickness of the ring will tell the scientists what the climate was like
• Pollen analysis


  • Pollen from plants gets preserved in sediment, scientists can identify and date preserved pollen to show which species were living at that time and compare the climate
• Temperature records since the 1850s


  • Global temperatures have been measured accurately using thermometers, this gives us a reliable but short-term record of temperature change
• Natural causes of climate change

  • Orbital change
  • Volcanic activity
  • Solar output
• Orbital change


  Can affect how much solar radiation the earth receives, the more energy the warmer
• Volcanic activity


  Major volcanic eruptions eject large quantities of material into the atmosphere, some of these particles reflect the sun's rays back out to space so the earth's surface is left cooler
• Solar output


  The sun's energy output is not constant, it changes due to short cycles
• Human causes of climate change

  • Burning fossil fuels
  • Farming livestock
  • Rice paddies
  • Deforestation
  • Cement production
• Burning fossil fuels


  Carbon dioxide is released into the atmosphere when fossil fuels like coal, oil, natural gas and petrol are burnt
• Farming livestock


  Produce a lot of methane
• Deforestation


  Plants remove carbon dioxide from the atmosphere, so when they are cut down they stop taking in carbon dioxide
• Cement production


  Made from limestone which releases carbon dioxide into the atmosphere
• Strategies to manage climate change

  • Mitigation
  • Adaptation
• Mitigation


  • Includes carbon capture and planting trees
• Adaptation


  • Includes changing agricultural systems, using biotechnology to sustain optimum conditions, and managing water supplies