Paleoclimate, productivity and anthropogenic eutrophication: Drawing inferences from paleolimnological proxy records of the Kashmir Valley, northwestern Himalaya

Lacustrine sediments, due to their widespread abundance across continents, are valuable archives of the past climate changes. The Kashmir Valley in the northwestern Himalaya, India situated at the interface of Western Disturbances and Indian Summer Monsoon moisture sources preserves undisturbed lacustrine deposits that serve as a valuable archive of past climate conditions. The spatio-temporal variability of these two monsoon moisture sources have been responsible for the Holocene climate perturbations and paleolimnological processes in the Kashmir Himalaya. The global and regional climate shifts aided by the anthropogenic forcing raises the need for a better understanding of the Holocene climate shifts and paleolimnological processes. We studied the available literature on lacustrine proxy records in order to understand the Holocene paleolimnological changes and to decipher paleoclimate, productivity and anthropogenic influences in the Kashmir valley. The analysis of the lake proxy records revealed significant changes in the regional paleoclimate conditions, lacustrine productivity and swings between drier and wetter phases. Furthermore, the region experienced a significant increase in the monsoonal precipitation during the early Holocene, followed by a progressive decline in the monsoonal rains and subsequent decreased lake water-levels and accelerated eutrophication during the late Holocene and recent times. In order to better comprehend the Holocene climate variability and its regional coherence, we compared these lake records with the regional Himalayan lakes and have elaborated about how paleolimnological processes respond to the shifting tropical-subtropical monsoon dynamics. The response of paleolimnological processes to a number of brief wet (Holocene Climate Optimum, Roman Warm Period and dry (Dark Age Cold Period and Little Ice Age) events has not been thoroughly investigated from this region, despite these events having been extensively observed from other lake systems in the Indian Himalaya. We suggest that several other lacustrine sites should be explored to generate high fidelity paleolimnology records with a stronger chronological framework to investigate the response of lacustrine processes to these short-term wet and drier phases.