Short answers, pulled from the story.
The Little Ice Age was a period of regional cooling, particularly pronounced in the North Atlantic region, that was not a true ice age of global extent. It is conventionally defined as extending from the 16th to the 19th centuries, though some experts prefer a span from about 1300 to about 1850. The term was introduced into scientific literature by François E. Matthes in 1939.
Scientists have proposed at least seven possible causes, including decreased solar activity, heightened volcanic activity, changes in ocean circulation, orbital forcing, and population collapses causing reforestation. Volcanic activity is considered the stronger driver by numerical climate modelling; a 2012 paper by Miller et al. linked the onset to four large sulfur-rich eruptions over 50 years, beginning with a massive tropical eruption in 1257 possibly from Mount Samalas in Lombok, Indonesia.
Winter temperatures in Central Europe during the 17th century ran about 1.2 degrees Celsius below the 1961-1990 average, and 19th-century winters were also about 1.2 degrees Celsius below that same average based on thermometric measurements. A reconstruction by historian Christian Pfister and climatologist Heinz Wanner, published in 2021, found that summer temperatures in the 16th century were around 0.2 degrees Celsius below the 1961-1990 average.
The number of witchcraft trials rose as temperatures dropped and fell when temperatures rose. Beginning in the 1380s, European populations began linking magic to weather-making, the first systematic hunts started in the 1430s, and by the 1480s witches were held responsible for livestock epidemics, late frosts, and crop failures. Scholars Oster (2004) and Behringer (1999) both argued that the resurgence was driven by climatic decline, with peaks of persecution overlapping the hunger crises of 1570 and 1580.
Between 1632 and 1641, rainfall in the Huabei region of China dropped by 11 to 47 percent from historical averages, and the Shaanbei region along the Yellow River experienced six major floods. Famine from extreme snowfall had already struck Manchuria from 1573 to 1620, fueling resentment among the Jurchen people that led to the founding of the Later Jin dynasty in 1616. In 1644, Li Zicheng's forces entered Beijing and overthrew the Ming dynasty.
The Little Ice Age made North America far colder in winter and hotter in summer than European settlers expected, and it coincided with severe drought. Tree ring studies from the University of Arkansas found that colonists at Roanoke arrived during the largest drought of the past 800 years. Historians agree that when colonists settled at Jamestown it was one of the coldest periods in the last 1,000 years, and the combination of cold, drought, and conflict contributed to the collapse of many early settlements.