Rates of temperature change in China during the past 2000 years

Abstract

Using 24 proxy temperature series, the rates of temperature change in China are analyzed at the 30- to 100-year scales for the past 2000 years and at the 10-year scale for the past 500 years. The results show that, at the 100-year scale, the warming rate for the whole of China in the 20th century was only 0.6±1.6°C/100 a (interval at the 95% confidence level, which is used hereafter), while the peak warming rate for the period from the Little Ice Age (LIA) to the 20th century reached 1.1±1.2°C/100 a, which was the greatest in the past 500 years and probably the past 2000 years. At the 30-year scale, warming in the 20th century was quite notable, but the peak rate was still less than rates for previous periods, such as the rapid warming from the LIA to the 20th century and from the 270s–290s to 300s–320s. At the 10-year scale, the warming in the late 20th century was very evident, but it might not be unusual in the context of warming over the past 500 years. The exact timing, duration and magnitude of the warming peaks varied from region to region at all scales. The peak rates of the 100-year scale warming in the AD 180s–350s in northeastern China as well as those in the 260s–410s and 500s–660s in Tibet were all greater than those from the mid-19th to 20th century. Meanwhile, the rates of the most rapid cooling at scales of 30 to 100 years in the LIA were prominent, but they were also not unprecedented in the last 2000 years. At the 10-year scale, for the whole of China, the most rapid decadal cooling in the 20th century was from the 1940s to 1950s with a rate of −0.3±0.6°C/10 a, which was similar to rates for periods before the 20th century. For all regions, the rates of most rapid cooling in the 20th century were all less than those for previous periods.