A Review of the Indian Monsoon Variability during the Holocene from the Speleothem records

Abstract

The Indian summer monsoon (ISM) is the large land-ocean-atmosphere linked system that carries significant amounts of moisture over the Indian Ocean into the Indian subcontinent during the summer, reaching as far north-west as Pakistan and as far north as the southern Himalaya. Changes in the ISM's. Changes in the ISM's strength and seasonality have a substantial impact on the region, but the mechanisms of change and the ISM's drivers are little understood. India has a very distinct seasonal climate, which is governed by Indian Summer Monsoon. Because of the region's vulnerability to floods and droughts, detailed and highly resolved paleoclimate reconstructions are needed to determine the recurrence and driving factors of ISM changes. Several studies have been published in the last few decades that used Stalagmite-based proxies such as oxygen isotope (δ18O) and carbon isotope to reconstruct the ISM. These reconstructions enable researchers to investigate ISM drivers and responses, improving monsoon predictability. Climate and environmental conditions in the Indian subcontinent over the last 10 ka (Holocene) are inferred using stable Oxygen isotope (δ18O) from different Indian caves. Here, this study focusses on stalagmite δ18O records from the Indian continent at the proximal end of the ASM region. On decadal to multi-centennial timescales, Indian stalagmite δ18O records shows well-dated, high-amplitude changes in response to the Indian Summer Monsoon’s most dominant drivers such as solar insolation, changes in the North Atlantic region, El-Nino Southern Oscillation (ENSO) dynamics, etc., indicating a close relationship between them mediated by the atmospheric changes through ITCZ shifts.