Evidence for Climate Change (OCR GCSE Geography)

Changes in the global climate

• Climate change is large-scale, long-term changes in the average temperatures and weather patterns
• The global climate conditions of the Earth change over time leading to colder and warmer periods
• The last 2.6 million years are the Quaternary period when there have been 60 cold periods and warmer interglacial periods
• The last ice age ended approximately 25,000 years ago

Ice core data: changes in temperature over the last 11,000 years

Ice core data: changes in temperature over the last 11,000 years

• The evidence for the climate change comes from a range of sources

Ice cores 

• These trap ash, air bubbles and microbes.
  • The air bubbles contain CO₂ providing information about past temperatures
  • Ice cores give information regarding the climate for the last 2.6 million years

Preserved pollen

• Allows scientists to know which plants were located where 
  • The climate requirements of those plants can then be used to know what the climate conditions were 

Historical sources

• Diaries and art: such as paintings of the Thames River frost fairs
  • These are subjective and so may be inaccurate

Tree rings

• Each ring of the tree shows a year's growth
  • During warmer and wetter years trees grow more and so the rings are larger
  • Fossilised tree remains enable scientists to examine the climate over thousands of years

Art and diaries

• Paintings and diaries provide evidence seen by people during past colder and warmer periods
  • Paintings of the frost fairs on the river Thames in London in the 19th Century
  • Diaries kept by people such as a gentleman farmer from North-West England dating back to 1815