MINI CASE 15.2
Correlation can be used as part of a debate as the following example illustrates.

A popular theory of climate change sceptics is that global warming is simply the natural fluctuation of the global climate. This idea was advanced in March 2007 by the Channel 4 documentary ‘The Great Global Warming Swindle', where it was suggested that climate change was not a result of carbon emissions rather it was blamed on variations in the Sun's activity. The documentary was heavily criticized for distorting scientific data to fit the sceptic argument.

The results of a study, led by Professor Mike Lockwood, a solar physicist at the Rutherford Appleton Laboratory, published later in the year refuted the programme's claim. The study showed that ‘over the past 20 years, all the trends in the Sun that could have had an influence on the Earth's climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures ... the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified'. (Lockwood & Frohlich, 2007). In other words there is a negative correlation between the earth's temperature rise and the sun's output.