Evidence of Climate Change

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  • Evidence of Climate change
    • Long Term
      • Oxygen Isotopes
        • sampled from ice and sediment cores
        • ration of oxygen 16 to 18 is a good indicator of past sea levels
        • ice from glacial periods are enriched with oxygen 16
      • Ice cores - CO2 levels
        • bubbles trapped
        • levels have  varied between 190 ppm - 280 over last 800,000 years
        • made up of layers - one layer formed every year
          • can use different layers to detect temperaturefor different years
      • Sea Level Change
        • affected by volume of water stored as ice
        • past sea levels shown by raised beaches
    • Medium Term
      • Pollen Analysis
        • pollen from plants often reserved in sediments
          • found in peat bogs
        • can be identified and dated to when it was released
        • compare conditions that plants live in now with back then
      • Tree Rings
        • new tree ring formed each year
        • thick ring = good conditions
        • scientists can take cores and find the age of the tree from the rings
        • can reliably show climate change from 10,000 years ago
      • Retreating Glaciers
        • can be tracked by paintings, direct measurements, and photographs
        • can tell how big glacier was from how far it extended
          • looking at position of rocks deposited
        • if glacier is miles away from rocks indicates climate change
    • Short Term
      • Weather records
        • consistently be collected since 1861
        • used to show climate change over short period of time
      • Polar Ice Melt
        • melting of Greenland ice sheet has increased by 16% since 1979
        • increased melting shows increased temperatures
      • Ecosystem Changes
        • changes in temperature affect availability of food and shelter
          • affect what species live in area
        • can be used to show climate change


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