by A. Watts, February 11, 2018 in WUWT
1. During the first 2000 years of our 5000-year civilization, most of the time, the annual average temperature was 2ºC higher than now. The temperature in January was 3-5ºC higher than now.
2. From then on, there was a series of temperature fluctuations. The lowest temperatures occurred in AD 1000, 400, 1200, and 1700. The range of fluctuation was 1-2ºC.
3. In every 400-800 period, a smaller cycle lasting 50 to 100 years can be detected with a temperature range of 0.5 -1ºC.
4. During the above cycles, it seems that any coldest period started from the Pacific coast of East Asia. The cold waves then moved westward to Europe and the Atlantic coasts. And at the same time, there were also trends from the North to the South.