2005 was the warmest year in the history of Australia and the second warmest in the history of the Earth since records have been kept. Ten of the Earth’s 11 warmest years have occurred since 1990. The European summer of 2003 was so hot that, according to the statisticians, it was a one in 44,000 chance. Since the mid-1990s ferocious hurricanes, whose intensity is directly linked with the temperature of the sea, have occurred with an unaccustomed regularity in the Gulf of Mexico. Mitch in 1998 killed ten thousand people. Katrina in 2005 took out New Orleans. During the 1990s in the South Pacific there were five consecutive El Niños, an unprecedented event. In the summer of 2002 the Arctic and Greenland ice sheets shrank by one million square kilometres. In February of the same year, at the other end of the world, the Larsen ice sheet broke up in a matter of weeks. You may regard all this as coincidence. Despite my naturally sceptical temperament, I do not.
During the 1980s the world received its first great post-industrial environmental shock. By the use of chlorofluorocarbons as a manufacturing convenience in refrigerators and spray-cans a hole began to appear in the ozone layer protecting human beings and the Earth from the sun’s ultraviolet rays. If instead of chlorine, bromine had been chosen, with a capacity to destroy ozone thirty times as great, by the time the link had been discovered the ozone layer most likely would have been entirely destroyed.
After solid scientific understanding of the threat of CFCs had been reached, 20 countries of the developed world in 1987 signed the so-called Montreal Protocol. It proved a triumph of effective global action and of reason. CFCs were soon more or less entirely removed from industrial production. The ozone layer began to repair itself.