Temperature variability inferred from tree rings of Qinling region in north-central China

Based on nine published tree-ring records, we analyzed the regional temperature variability for the past 250 years in the Qinling Mountains in North-central China, where the tree-growth is known to be sensitive mainly to the early-spring and early-summer temperatures. The comparison among these reconstructed temperature series showed that variations of the early-spring and early-summer temperatures were out of phase in the past. The inverse relationship between spring and summer temperatures were found in 1920–1925 (cold springs coincided with warm summers) and 1949–1952 (warm springs coincided with cold summers). On the other hand, consistently warm seasons occurred during the period 1898–1908. The warming trends were obvious for both spring and summer temperatures during the late 20th century. However, the early spring temperatures had increased rapidly since 1965, while the early summer temperatures became warm after 1980. An amalgamation of the series revealed three distinct warm periods (1857–1875, 1896–1938 and 1987–2002) and four cold intervals 1823–1828, 1848–1849, 1883–1895, 1940–1985 and the late 20^th century.