THE PRECEDING chapters have considered the various strands of the global warming story and the action that should be taken. In this last chapter I want first to present some of the challenges of global warming, especially those which arise because of its global nature. I then want to put global warming in the context of other major global problems faced by humankind.

Global warming – global pollution

A hundred years ago, the French painter Claude Monet spent time in London and painted wonderful pictures of the light coming through the smog. London was blighted by intense local pollution – from domestic and industrial chimneys around London itself. Thanks to the Clean Air Acts beginning in the 1950s, those awful smogs belong to the past – although London's atmosphere could be still cleaner.

Today, however, it is not just local pollution that is a problem but global pollution. Small amounts of pollution for which each of us are responsible are affecting everyone in the world. The first example to come to light was in the 1970s and early 1980s when it was realised that very small quantities of chlorofluorocarbons (CFCs) emitted to the atmosphere from leaking refrigerators, aerosol cans or some industrial processes resulted in significant degradation of the ozone layer. The problem was highlighted by the discovery of the ozone hole in 1985.