Climate Change

• Climate Change A01

  Climate Change is a sustained change in the average global temperature, for example the 1.1 ° increase in global temperatures since 1800. This is caused by increasing atmospheric CO2 concentrations driven by human activity with an increase from 280 ppm to 420 ppm since 1800. The IPCC predicts in the worst case scenario (RCP8.5) where CO2 emissions continue to rise, that temperatures may increase by as much as 4.5 ° by 2100, with up to a 1 m rise in sea levels. These changes are likely to impact _____.
• Methods to reconstruct our climate?

  • Ice cores
  • Tree rings
  • Fossils
  • Lake sediment- Pollen Grains, diatom and valves
  • Marine sediment - fossil shells
• Ice cores


  • Ice cores contains tiny bubbles of air trapped during the initial ice formation
  • They provide a record of the gaseous composition of the atmosphere in the sea floor sediment
• Marine sediment


  • Fossil shells of tiny sea creatures called foraminifera accumulate in the sea floor
  • These shells consist of calcium carbonate
  • The chemical composition of these shells can tell us the sea level and temperature from millions of years ago
  • The deeper into the core, the further back in time
• Lake sediment


  • Lake sediment contains pollen grains, diatoms and valves which can help reconstruct the past climate
  • Pollen grains are used to show the past vegetation types -> it infers the type of pollen, the type of tree around the lake > therefore type of climate
  • Diatoms are microscopic plants found in the lake sediment. Their shells are made from silica dioxide which helps preserve them. An abundance in diatoms indicates a warmer climate
  • Valves are made of light and dark bands
• Tree rings 


  • Enables us to date past events of climate change
  • Each annual growth ring marks a year in the trees life and represents a complete cycle of seasons of growth
  • They vary in width depending on the temperature and moisture levels during its growing season eg. warmer temperature > promotes faster tree growth > wider rings
• Fossils

  • Indicate the climate conditions through coral reefs, which are highly sensitive to temperature, water depth and sunlight
  • Coral skeleton consists of calcium carbonate which is extracted from seawater. This contains oxygen isotopes which determines the temperature
  • The higher frequency of oxygen isotopes, the higher the temperature
• What does paleoclimate mean?


  The past climate
• Why is it important to study past climate change?

  It allows us to understand climate change today and predict future climate change
• • Over hundreds of millions of years the earth's climate has fluctuated between greenhouse conditions and icehouse conditions
  • Within these periods there are glacial and interglacial periods which occur on a small time scale
• Greenhouse conditions


  • High CO2 levels
  • High global temperatures
  • High sea levels
• Icehouse conditions


  • Low CO2
  • Low global temperatures
  • Large parts of the continental surfaces covered by ice