Evidence for Climate Change

• Climate change is any significant change in the earths climate over a long period
• the Quaternary period is the most recent geological time period, spanning about 2.6 million years ago to present day
• before the quaternary, the earths climate was warmer and stable
• during the quaternary, global temperature shifted from cold glacial periods to warmer interglacial periods
• the earth has been warming as the last glacial periods ended around 15,000 years ago
• ice cores

  ice sheets are made up of layers of ice

  • one layer is formed every year

  1. scientists drill into ice sheets to get long cores of ice
  2. they analyse the gases trapped in the ice
  3. tells us the temperature for every year

  one ice core from antarctica shows the temperature change over the last 400,000 years
• sea ice positions

  sea ice formed around the poles and melts in the summer

  • by observing the maximum and minimum extent of sea ice each year, scientists can tell how the ocean temperature changes
  • reliable data but records dont go far back
• diaries and paintings

  historical diaries can show what the climate was like in the past

  • paintings of frozen rivers show that winters in Europe were colder 500 years ago than now
  • however not very reliable as it is just one persons viewpoint
• temperature data

  since the 1850s, global temperatures have been measures accurately using thermometers

  • however weather stations are not evenly distributed across the world