Climate change explained

With so much information on this issue out there, the following is a snapshot of climate change.

• Heat from the sun enters our atmosphere, bounces off the Earth's surface and returns to space. The Earth's blanket of naturally occurring gases, including water vapour, carbon dioxide, methane and nitrous oxide, traps some of the sun’s heat in the atmosphere. This is a natural process known as the 'greenhouse effect'.
• Human activity since the Industrial Revolution in the late 1700s has increased the concentrations of the naturally occurring gases in the atmosphere and introduced new human-made ones such as sulfur hexafluoride, perfluorocarbons and hydrofluorocarbons.
• The burning of fossil fuels combined with increased levels of land clearing means more carbon dioxide is being added to the atmophere at the same time as the number of trees (which help remove carbon dioxide from the atmosphere) have decreased. As a result, the atmospheric concentration of carbon dioxide has increased by 35 per cent and is the highest it’s been for 650,000 years.
• Concentrations of methane have also risen 151 per cent, mainly due to increased food production, and nitrous oxide by 17 per cent, mainly due to the burning of fossil fuels and use of fertilisers.
• As a result, the blanket of gases has thickened and is trapping more heat than before, therefore raising surface temperatures.
• The Intergovernmental Panel on Climate Change has concluded that human activities which increase greenhouse gas concentrations are "enhancing" the natural greenhouse effect and resulting in a changing climate.
• The Earth’s plants and animals, as well as the crops and water resources that we use to sustain our communities, are all linked to the climate. A changing climate will alter the complex web of systems including weather patterns, ocean currents and the distribution of plant and animal species that allow life to thrive on earth. Even the minimum changes forecast could mean frequently flooded coastlines, disruptions to food and water supplies and the extinction of many species.
• Evidence to support a changing climate globally includes:
  • Eight of the ten warmest years on record have occurred in the past ten years.
  • Sea levels have risen 1.8mm each year since 1950 and that rate is accelerating.
  • There have been fewer frosts and the ice sheets of Antarctica and Greenland are shrinking.
  • The area of Arctic ice dropped by 22 per cent between 2005 and 2007 — that rate is 10 per cent higher than the worst case scenario developed by the Intergovernmental Panel on Climate Change.
  • Timing of physiological processes in plants and animals throughout the world is changing.
  • The Earth’s average surface temperature has risen by 0.7°C since 1900.
  • Average temperatures in Australia rose 0.9°C from 1910 to 2004.
• Serious and long-term global action is needed to reduce greenhouse gas emissions to slow the rate of global climate change.
• On an individual level, we will need to change the nature and patterns of our activities that increase greenhouse gas, including the amount and type of energy we use and the way we use transport.