Quasi-periodicity of temperature changes on the millennial scale *

Abstract

Abstract Quasi-periodicity of temperature changes on the millennial scale is found according to the proxy data both from historical documents and natural evidence in China. The auto-correlation of the temperature changes series for the last 2000 years is most significant on the 1350 a time lag. The period of 1350 a includes 4 warm/cold stages: 200–250 a warm stage, 150–200 a cold stage, 300–350 a warm stage, and 550–600 a cold stage. In contrast to the 550–600 a cold stage, the other three stages can be united in one warm dominant stage. Inferred from the 1350 a period, the 20th century warm stage belongs to the 200–250 a warm stage, which is similar to the warm stage occurring during the 570's-770's. The process of temperature change in the 20th century warm stage is similar to that of the 570's–770's. But the warming rate in the 20th century is more rapid. The temperature anomaly in the 1980's–1990's shows a greater departure from the regression equation of that between 1500's–1900's and 150's–650's. Wh...