The ‘Little Ice Age’ wasn’t a true ice age, but a period of significant cooling that took place worldwide (though it was felt most keenly in northern Europe) over the course of 500 years. It was punctuated by several brief warming periods with the coldest period manifesting itself in the late-17th and early-18th centuries. It’s during the winters over this period that the European landscape completely changed to something evocative of what might happen if a real ice age occurred. Over the bitter winter of 1683-1684, the River Thames in London completely froze over for two months and in Switzerland entire villages were lost to advancing glaciers.
Evidence suggests that this period of global cooling could have been caused by a number of factors combined. Volcanic activity around Indonesia in the 13th century had a likely long-term effect, while a very slight shift in the Earth’s orbit at this time definitely contributed. The dips in this cooling period also coincided with minimums in solar activity.