However, there are still disagreements about exactly what is happening and what is likely to happen, and much general speculation. Certainly there is room for debate over the longer term prognosis, given our imperfect understanding of the very complex processes at work in climate systems, for example, in relation to the role played in climate change by
clouds. The IPCC is increasingly confident that their general conclusions are correct and that the uncertainties in the predictions have been reduced, but there is a minority view that is less sure. Indeed, the so-called ‘contrarian’ position was initially that climate change was not in fact happening. There was much made of satellite data which showed cooling rather than warming. However, one would expect reduced radiation outwards from the planet as a result of an enhanced greenhouse effect, although this does not entirely explain the temperature anomaly in the outer atmosphere. Nevertheless, the surface data, which have been collected over a much longer period, consistently showed warming. As that became more apparent in reality, contrarians have tended to move on to claiming that there are other possible causes than human activity, one of the more prominent contrarian explanations being variations in solar activity (Calder 1997).