Little Ice Age cooling in the Western Hengduan Mountains, China: a 600-year warm-season temperature reconstruction from tree rings

The distributions of forest, ice and snow in the Hengduan Mountains of China have undergone significant changes due to ongoing climatic warming. To better understand the spatiotemporal pattern of temperature changes in the Hengduan Mountains, we used tree-ring cores collected from multiple individuals of Larix speciosa Cheng et Law at five sites to develop a regional chronology and to establish the relationship between tree-ring radial growth and warm-season (May-September) mean temperature. The regional chronology accounts for 46.1% of the observed variance in the warm season and was used to reconstruct regional temperature levels back to 1420. Four cool intervals (1490-1570, 1590-1660, 1700-1790, and 1800-1880) indicate that the Western Hengduan Mountains experienced the Little Ice Age, and the changes were synchronous with cooling on the Tibetan Plateau and in the Northern Hemisphere, demonstrating a well-defined Little Ice Age signal in the South Asian monsoon region. Air-sea interactions and solar activity affected the variability of the warm-season mean temperature variations on interannual or interdecadal scales. Our temperature reconstruction improves the understanding of multi-centennial climate change in the Western Hengduan Mountains and has implications for advancing high-resolution paleoclimate science in the region.