Climate change

• Natural hazard


  Climate change
• Climate change


  • It is the result of natural and human actors
  • It has a range of effects
• The Quaternary Period is from about 2.6 million years ago to the present
• The Quaternary Period is characterised by the appearance of humans, and includes the Pleistocene and Holocene epochs
• The Pleistocene epoch was from about 2.6 million years ago to 12,000 years ago
• The Holocene epoch has been from 12,000 years ago to the present day
• Some geologists think we should now use the term Anthropocene Epoch because human activity is now affecting the way the Earth system operates
• Ice cores, ocean sediment cores, tree ring analysis, and measurements of ice volume and surface/ocean temperatures provide evidence for climate change in the Quaternary Period
• Ice cores show how gas trapped in ice has changed over 300,000 years, revealing temperature variations over 100,000 year cycles (ice ages)
• Ocean sediment cores show what plants, animals, and pollen were deposited, helping to show how temperature has changed over the last 100,000 years
• Tree ring analysis shows growing seasons (wider rings = warmer) for the last 10,000 years
• Measuring the thickness of ice at the poles and glaciers allows calculation of changes in temperature (thicker ice = colder)
• Scientific equipment has become more accurate over the last 100 years, including the use of satellites to record temperatures
• The evidence from different methods supports each other in showing climate change
• In the Pleistocene there were 100,000 year cycles of ice ages, with very short (5,000 year) interglacial warm periods
• Over the last 10,000 years (the Holocene) it has remained warm, and we are overdue an ice age, likely due to human activity
• Greenhouse effect


  The warming of the Earth's atmosphere due to human activity increasing the layer of greenhouse gases
• The sun emits shortwave radiation which enters the atmosphere, some of which is reflected by white surfaces like ice and snow, and the rest is absorbed by the Earth and re-emitted as longwave radiation (heat)
• Greenhouse gases trap some of this energy, keeping the Earth an average of 15°C warmer than it would be without this effect
• Human activity such as transport, industry and agriculture increases the concentration of greenhouse gases, trapping more of the sun's energy and causing the atmosphere to heat up
• Fossil fuels


  • Coal
  • Gas
  • Oil
• Carbon emissions from fossil fuels have been increasing rapidly, with the biggest increases in the 20th century
• Cement production is a major source of carbon emissions
• Higher wealth (GNI per capita)

  Higher carbon emissions per capita
• Solar Output


  • Causes ice ages
  • Cycles of warmer/cooler periods of 11 years
  • Longer cycles of 100s years
  • Reduced output = cooler on Earth
• Orbital Changes


  • Cycle of 400,000 years from a circle to an ellipse
  • In a circular orbit the Earth is closer to the sun so gets warmer
• Volcanic Activity


  • Large eruptions emit CO2 which is a greenhouse gas-warming
  • Also emit sulphur dioxide-short term cooling effect
• Natural causes like solar output and orbit changes are not responsible for current warming because the cycles are too short or too long to explain the past climate change
• We haven't had frequent enough volcanic eruptions in the past 200 years to explain the current warming
• Human Enhanced Greenhouse Effect

  • More Greenhouse gases
  • More Solar Radiation trapped
• The human enhanced greenhouse effect is responsible for the current climate change