## 1 Introduction  
Climate change can lead to changes in the shape, area and volume of mountain glaciers [1; 2; 3; 4; 5]. Therefore, glacial landforms with chronological evidence (e.g., terminal and lateral moraine ridges) can be used to reconstruct paleoglacial surfaces as well as paleoclimate features for specific periods [6; 7; 8; 9]. The Last Glacial Maximum (LGM) is the closest extreme cold period to modern times. Globally, there was massive sea retreat accompanied by a dry and cold climate. Glaciation occurred on the Tibetan Plateau (TP) and its surrounding mountains during the Last Glacial Maximum (LGM), as well as in the coastal mountains of East Asia, but the magnitude of this glaciation varied [10; 11; 12; 13]. Although environmental changes followed roughly similar patterns globally, different regions experienced differing magnitudes of glaciation and climate change [14; 15]. It is therefore important to study the LGM's climatic and environmental characteristics in order to clarify how temperature and precipitation drove glacial advances and leaded to climate change. Analyzing the extent to which there was environmental heterogeneity between different regions is key to understanding climate change today [16]. However, current paleoclimate reconstructions in the LGM are mainly focused on the Tibetan Plateau and its surrounding mountain ranges [17; 18; 19; 20; 21; 22; 23], and there are few relevant studies for the mountainous regions of eastern China [24], which hinders the comparison of LGM climate change between the Tibetan Plateau and other mountainous regions.  
The development of glaciers in eastern China is closely related to the influence of the East Asian monsoon (EAM) [13]. Since the influence of the monsoon on the climatic and geomorphological environment of the Quaternary Period is particularly relevant to the history of the global ice age change [11], the quantification of the paleoglaciers and paleoclimate in the eastern Tibetan Plateau during the LGM can provide a better understanding of climate change in eastern China, and is of great significance for understanding the paleoenvironment under the influence of the East Asian monsoon. The Tianchi area of the Changbai Mountains, representative of a once-glaciated area within this EAM-controlled environment of East Asia, is sensitive to global environmental change. The Tianchi area of the Changbai Mountains contains a rich archive of glacial relics; however, there are no quantitative reconstruction studies of the paleoclimate in this study area. In order to bridge this gap, we firstly reconstructed the paleoglacial surface of the LGM in the Tianchi area. Then, we calculated the the equilibrium line altitude (ELA) values for the LGM as well as for the modern era. And, finally, we inferred the paleoclimate of the Tianchi area during the LGM by using the ELA-related climate models (P-T and LR models) in combination with data from high-elevation meteorological stations. In addition, possible climatic driving factors during the LGM in the Tianchi area are discussed. The paleoclimate reconstruction results of this study area are statistically analyzed with those of the mountainous areas affected by the East Asian monsoon and the Indian monsoon, in order to identify the common features of the paleoclimate variations under the influence of the monsoon.