Maximum July-August temperatures for the middle of the southern Tien Shan inferred from tree-ring latewood maximum densities.

Long-term temperature reconstructions are urgently needed to prolong meteorological climatic data, which are too short to evaluate the anthropogenic effect on climate change since the Industrial Revolution. The maximum latewood chronology (MXD) of Picea schrenkiana in the middle of the southern Tien Shan was established, and it showed a strong correlation with the mean maximum temperature of the current July to August (T), with r = 0.773 (p < 0.001, 1959-2016), which implies that a high temperature in the late growing season could increase the cell wall thickness and lead to high latewood density. Then, the T of the middle of the southern Tien Shan was reconstructed over the period of 1720-2018. Three MXD chronologies from Kyrgyzstan significantly correlated with our T reconstruction at the interannual scale, and they also showed similar variations on decadal scales. None of these MXD series showed a warming trend in the past century, which was also found in several MXD series from different regions of the world. Spatial correlation analysis revealed that our T reconstruction showed significant correlations with that in eastern Asia, southern Europe, and north-western Africa, forming a teleconnection called the Silk Road Pattern. However, moving correlation analysis between our T reconstruction and Hokkaido temperature series indicated that this teleconnection was unstable in the past 3 centuries. The volcanic eruptions from the mid-high latitudes in the Northern Hemisphere showed a stronger cooling effect than those from the Southern Hemisphere and the low latitudes of the Northern Hemisphere. The summer North Atlantic Oscillation was also shown to affect the temperature in the Tien Shan to a certain extent.