Summer temperature variability inferred from tree-ring records in the central Hengduan Mountains, southeastern Tibetan Plateau

摘要

Current understanding of the paleoclimatic variability across the Tibetan Plateau (TP) is still limited because of the lack of long-term climatic records. We developed a regional tree–ring width chronology ofPicea likiangensisvar.balfourianafrom the central Hengduan Mountains region, in the southeastern TP. Climate-growth correlation analysis revealed that the current year’s July (cJuly) and the current year’s August (cAugust) mean minimum temperature was the main climatic factor controlling tree-ring growth. Using a linear regression function, we reconstructed this indicator for the past 214 years (1795–2008) to produce the first mean minimum temperature reconstruction for the central Hengduan Mountains. The reconstruction satisfied all statistical calibration and validation tests, and represented 35.9% of the temperature variance recorded over the 1958–2008 instrumental period (34.6% after adjusting for the loss of the degrees of freedom). During the past 214 years, two major cold periods were identified from 1839 to 1853 and 1857–1942, and four major warm periods from 1802 to 1813, 1819–1838, 1972–1981, and 1988–2008. The degree of warming from 1988 to 2008 was unprecedented over the past two centuries. Spatial field correlation with the gridded temperature dataset revealed that our reconstruction captures large-scale regional temperature variations for the southeastern TP and its vicinity. The reconstructed variations were consistent when compared to other regional temperature datasets, historical documents, and records of glacier fluctuations in the surrounding high mountains. This consistency with multiple records suggests that our reconstructed sequence is reliable and it could represent historical large-scale temperature changes on the southeastern TP.