High-resolution climatic (monsoonal) variability reconstructed from a continuous ∼2700-year sediment record from Northwest Himalaya (Ladakh)

A chronologically well-constrained sedimentary archive from Upshi (Ladakh) was studied using a multi-proxy approach namely palynology, environmental magnetism, total organic carbon (TOC), total nitrogen (TN), stable isotopes of carbon and nitrogen providing a continuous vegetation, and paleoenvironmental history spanning the last similar to 2700 years with a temporal resolution of similar to 43 years. Pollen assemblage shows non-arboreal pollen (NAP) and non-pollen palynomorph (NPP) were dominant around the Upshi from similar to 2646 to 2431 cal. yr BP, indicating warmer conditions. Arboreal pollen (AP) and NAP gradually increased from 2431 to 1860 cal. yr BP in the study area, under warm and wet conditions, corresponding to the Roman Warm Period (RWP). This phase also witnessed enhanced sediment delta N-15 and chi lf values. From similar to 1860 to similar to 1154 cal. yr BP increased Chenopodiaceae/Amaranthaceae and substantial spread of NPP suggest decreased temperature and prevalence of cold-dry climate. This period also records declining trends of chi lf, delta N-15, delta C-13(org), TOC, and TN contents. From similar to 1154 to 293 cal. yr BP, the vegetation type reversed to mixed conifer and broad-leaved forest with significant increase in herbaceous taxa, rising delta N-15, delta C-13(org), TOC, and TN suggesting warm and wet conditions in the study area. This period broadly corresponds to the 'Medieval Warm Period' (MWP). Among all the proxies employed, depth profiles of TOC and TN (wt%) appear to respond best against external climate forcing showing remarkable correlation(s) with residual Delta C-14 in atmosphere, indicating dominance of intrinsic solar variability on regional climate/environment. The reconstructed recorded is well connected with established historical events and cultural activities of the Eurasian region.