Evidence of Climate Change

Evidence of Climate Change

1. Long Term

   • Huge temperature change in the earths history
   • Last 400,000 years detailed fluctuations
   • Climate shifted between cold glacial periods last 100,000 years and warmer interglacial periods that last 10,000 years
   • Ice Cores- drill into ice sheets to get ice cores layer of ice forms every year. Analyse the gases trapped to tell what the temperature was each year and how its changed over time
   • Pollen Analysis- Pollen preserved in sediment can be identified and dated to show when it was released. Can tell what the conditions were like from the plant
   • Sea level change- Affected by the volume of water stored as ice sea levels are shown by raised beaches can be dated to when there was less water

2. Medium Term

   • Last glacial period ended 18,000 years ago.
   • Warming of the climate was fast but it wasn't constant switched back to cooler climate
   • 5000 years ago temperatures were 1-2C higher
   • Historical Records- Indicate different conditions in the past
   • Tree Rings- New ring each year and if conditions are good they will be thicker. Can look at how many rings and the thickness to see the climate of that year.
   • Retreating Glaciers- See how big glacier was and how far it extended by rocks deposited the distance shows climate change further away its increased

3. Short Term

   • Global warming used for rapidly increasing global temperatures risen sharply recently.
   • Overall pattern increase in temperature
   • Rose steadily from early 20th century until 1940s then dropped back down but have risen again rapidly
   • Weather Records- weather conditions have been collected since 1861 can see climate change over a short time
   • Polar Ice Melt- reduction in the amount of ice at both poles increased melting means increased temperatures
   • Ecosystem changes- Affect availability of food and shelter and where species live can see distribution of species has changed