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Greenhouse gases

Greenhouse gases in the earth’s atmosphere trap warmth from the sun and make life possible. Without them, temperatures at the surface of the earth would be about 30°C colder.

The major greenhouse gases include:

  • water vapour
  • carbon dioxide (CO2)
  • methane (CH4)
  • nitrous oxide (N2O).

Other greenhouse gases at lower concentrations include:

  • sulphur hexafluoride (SF6)
  • perfluorocarbons (PFCs)
  • hydrofluorocarbons (HFCs).

As a result of industrial and other activities, human society is now emitting greenhouse gases into the atmosphere in such quantities that the composition and dynamics of the atmosphere are changing.

Global increases in atmospheric carbon dioxide concentration are caused primarily by fossil fuel use and land-use change, while increases in methane and nitrous oxide are primarily due to agriculture. This increased concentration of gases traps more of the earth’s warmth than normal, leading to a gradual warming of the atmosphere.

To measure New Zealand’s contribution to global climate change, the following are reported:

Did you know?

  • Greenhouse gases are removed from the atmosphere by forests, because the trees absorb carbon dioxide as they grow – these are termed ‘forest sinks’ or ‘carbon sinks’.
  • Most of the increase in global temperatures since the mid-20th century is attributed to increased greenhouse gas concentrations caused by human activity.

This information has come from the latest national state of the environment report Environment New Zealand 2007.

 

Last updated: April 2009