Over the same period, the world‘s climate changed by an average of 0.05 degree Centigrade, as green house gases trap the Sun’s heat within the atmosphere. Computer models predict a continued warming of 0.5 degree a decade unless steps are taken to limit emissions. The climate change would be greater were it not for pollutants such as sulphur dioxide which scatter sunlight back into space. Other gases- notably CFCs from fridges, aerosols and fire extinguishers- are damaging the tenuous layer of ozone in the stratosphere which screens out ultra violet radiation from the Sun.
Steps have been taken to phase out CFCs. They are also powerful greenhouse gases, but legislation to reduce other green house gases will be harder to implement since the practices that produce them are central to modern life. Many nations have pledged to reduce emissions to their 1990 levels, but stronger measures will be needed for stop climate change.