Human activity over natural inputs determines the bacterial community in an ice core from the Muztag ata glacier

Ice core provides a valuable vertical timeline of past climates and anthropogenic activities. Environmental proxies have been widely used in these studies, but there are few biological indicators available. To address this gap, we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities. By analyzing the portion of the ice core with environmental proxies available (corresponding to 1907 to 1991), we observed an increase in bacterial richness throughout the ice core, which was associated with higher NH ₄ ⁺ , an indicator of agricultural development. The bacterial community was jointly determined by human activity, natural input, and air temperature, with a strong human influence after the 1950s. Furthermore, the relative abundance of animal gut-associated bacteria, including Aerococcaceae, Nocardiaceae, Muribaculaceae, and Lachnospiraceae, was associated with livestock number changes in the Central Asian region. Together with other bacterial lineages, they jointly explained 59.8% of the livestock number changes. This study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities, highlighting the potential of using bacterial proxies for ice core studies.