1250 to 1850 - The Little Ice Age
These were unusually cool centuries.
They followed hundreds of years of a warm, pleasant climate called the Medieval Warming.
Climate change did not suddenly start in 1970.
Climate change happened during the Little Ice Age with almost no man made carbon dioxide in the air !
During the Little Ice Age, there were four periods when the sun was unusually inactive, based on sunspot counts (a proxy for solar energy output, which is now measured directly with satellites).
All four periods of low sunspot counts were associated with unusual cloudiness, which blocked daytime sunlight more than usual, resulting in an an unusually cool average temperature.
There were also rapid changes in temperature and precipitation.
During the Maunder Minimum, for example, the years 1683 and 1684 were unusually cold, and then the years 1685 and 1686 were unusually hot.
Records for this period come from ships' logs, private diaries, military records, agricultural records such as wine harvest dates, and history books.
(1) 1280 to 1340 - The Wolf Minimum
(2) 1450 to 1540 - The Sporer Minimum
(3) 1645 to 1715 - The Maunder Minimum
(the coldest period of the Little Ice Age)
The temperature was so cold it led to famines in Europe
that killed millions of people from 1690 to 1700.
(4) 1795 to 1825 - The Dalton Minimum