What caused the Little Ice Age, and did it really shape history?

The Little Ice Age was not an ice age at all. It was a few centuries of regional cooling, strongest around the North Atlantic, usually dated from the 1500s to the 1800s (some say from about 1300 to about 1850). Averaged over the Northern Hemisphere, it was less than 1°C colder than the late twentieth century. Its cause is still debated, but the leading suspect today is volcanoes: climate models suggest eruptions did more of the cooling than a dimmer Sun.

The name came from the geologist François Matthes in 1939, and it has caused confusion ever since. The cold was patchy and uneven. In England, 1684 brought the coldest winter in the long Central England temperature record, the year of a famous frost fair on the frozen Thames, yet only two years later came one of the five warmest winters on record. So the period is best pictured as a time when brutal winters came more often, not as one long freeze.

The list of suspects is long: a quieter Sun during two spells of low solar activity, a run of big sulfur-rich eruptions starting in 1257, shifts in ocean currents, natural wobbles of the climate, and even forests regrowing on farmland emptied by plague and conquest. Historians then argue about what the cold did to people: witch trials rose as temperatures fell, unrest turned into wars, yet the Dutch Republic seems to have adapted and even profited from it.