Channel 4’s television programme The Great Global Warming Swindle last Thursday argued that climate change is caused by the Sun, not carbon dioxide.

The idea is that the Sun’s activity fluctuates, and when it grows stronger than usual the global temperatures on Earth rise. An important plank in this theory came in 1893, when the English astronomer Edward Maunder noted a dip in the Sun’s activity during the late 1600s and early 1700s. He found there were few sunspots on the surface of the Sun, with fewer solar storms erupting into space. On Earth, this caused far fewer incidents of the northern lights, the aurora borealis.

The dip in solar activity also seemed to match a bout of particularly cold weather. Savage winters regularly froze rivers and miserable summers ruined crops, and it seemed clear that the quiet Sun was driving this wretched weather. Or was it? In fact, the climate at this time was blowing hot and cold. For instance, 1666 is best known in England not for cold weather but for a year-long drought and scorching summer that led to the Great Fire of London in September that year.

On the other hand, the 1690s were so desperately cold that failed harvests led to famine and a drop in population numbers across much of northern Europe because of death and emigration.