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Sulphur cycle

The term 'sulphur cycle' is used to describe the ways in which sulphur is exchanged within and between the Earth's surface and the atmosphere.

This exchange involves various physical, chemical and biological processes, and takes place with sulphur in various organic and inorganic forms (e.g. as sulphur dioxide). It includes sulphate aerosols that scatter and absorb solar radiation, and indirectly affects cloud processes.

In detail

Sulphur gases are emitted from fossil fuel burning and are also emitted naturally by the oceans. They take part in chemical reactions in the atmosphere to form small particles called sulphate aerosols. These are eventually removed from the atmosphere by rain and clouds - having a typical lifetime of a few days. However, whilst in the atmosphere sulphate aerosols can have a substantial cooling effect on climate.

Find out more

  • The HadCM3 model used to produce the UKCP09 probabilistic projections includes some climate-sulphur cycle feedbacks but omits others. More details about the how the sulphur cycle is represented in UKCP09 are given in  in the UKCP09 Climate Change Projections report.  provides a list of the constituents included, and not included, in the UKCP09 probabilistic projections.
  • A discussion of sources of uncertainty in the UKCP09 probabilistic projections is available in  of the UKCP09 Climate Change Projections report.
  • IPCC Fifth Assessment Report, Working Group 1 report The Physical Science Basis, Chapter 6