
Image caption
A 2000-year temperature history of the Northern Hemisphere outside the tropics shows a warm period that peaked around 1,000 A.D. followed by a multi-century period of cooling: the Little Ice Age. The coldest part of the Little Ice Age overlapped the very low solar activity of the Maunder Minimum, but the cold spell began well before. NOAA Climate.gov graph, based on data from Christiansen and Ljungqvist, 2012.