It is true that when the alarm over global warming was set off in the 1980s and 1990s, the world was undoubtedly hotting up, apparently in tandem with an inexorable rise in CO2. But this rise in temperatures was not unprecedented. The world has in fact been heating up for 200 years, ever since it emerged from what climatologists call the “Little Ice Age’ when, between 1350 and 1800, it markedly cooled. The temperature rise of 0.5 degrees C between 1975 and 1998, hailed as “the hottest year in history” was no greater than that recorded between 1910 and 1940, before “global warming” was thought of.