A 414-year tree-ring-based April–July minimum temperature reconstruction and its implications for the extreme climate events, northeast China
A ring-width series was used as a proxy to reconstruct the past 414-year record of April–July minimum temperature at Laobai Mountain, northeast China. The chronology was built using standard tree-ring procedures for providing comparable information in this area while preserving low-frequency signals. By analyzing the relationship between the tree-ring chronology of Korean pine ( Pinus koraiensis) and meteorological data, we found that the standard chronology was significantly correlated with the April–July minimum temperature ( r = 0.757, p < 0.01). Therefore, the April–July minimum temperature since 1600 (more than six trees, but the expressed population signal (EPS) is greater than 0.85 since 1660) was reconstructed by this tree-ring series. The reconstruction equation accounted for 57.3 % of temperature variation, and it was proved reliable by testing with several methods (e.g., sign test, product mean test, reduction of the error, and coefficient of efficiency). Reconstructed April–July minimum temperature on Laobai Mountain showed six major cold periods (1605–1616, 1645–1677, 1684–1691, 1911–1924, 1930–1942, and 1951–1969) and seven major warm periods (1767–1785, 1787–1793, 1795–1807, 1819–1826, 1838–1848, 1856–1873, and 1991–2008) during the past 414 years. The reconstructed low-temperature periods in the 17th and early 18th century were consistent with the Little Ice Age (LIA) in the Northern Hemisphere, and the rate of warming in the 19th century was significantly slower than that in the late 20th century. In addition, the reconstructed series was fairly consistent with the historical and natural disaster records of extreme climate events (e.g., cold damage and frost disaster) in this area. This temperature record provides new evidence of past climate variability, and can be used to predict the climate trend in the future in northeast China.