Coupled Climate–Vegetation Dynamics over the last 15 ka in the Central Ganga Plain: A Multi‑Proxy Record from Kanwar Wetland, India

The Central Ganga Plain hosts many lakes that serve as archives for high-resolution palaeoclimatic reconstruction. However, climate cycles on millennial and shorter timescales remain poorly constrained in terrestrial records from the Indian subcontinent, especially in the wetlands of the CGP. Some previous research on these lakes has examined the regional Holocene climate variability, but these studies have been limited by the scarcity of high-resolution data. To better understand local and regional climate forcings and identify the main driver(s) of past C₃/C₄ vegetation shifts, Kanwar Wetland in the Central Ganga Plain was studied using various proxies, including mineral magnetism, sediment textural parameters, and stable carbon isotope (δ¹³C values), with chronological control provided by six AMS ¹⁴C ages. A ~3-meter-long sediment core retrieved from the Kanwar wetland allows for reconstructing millennial-scale climate variations over the past 15,000 cal yrs BP. The record reveals significant palaeoclimatic events, including the Bølling–Allerød (B/A), Younger Dryas, and shorter Holocene fluctuations. The B/A period aligns with a phase of strengthened Indian Summer Monsoon (ISM) over the CGP. Furthermore, the prolonged periods of weaker monsoon are evident in the Holocene, mainly around 10600, 8200, 6000, 4200, 2800, and between 1400 and 600 cal yrs BP. These episodes temporally coincide with reduced upwelling intensity in the western Arabian Sea, suggesting weaker ISM winds. Superimposed on these trends are notable short-term cycles of roughly 172–344 and 172–688 years around 12,000 and 14,000 cal yrs BP, as well as 86–344‑year cycles between 2,000 and 6,000 cal yrs BP, which suggest a significant role of external forcing, especially solar variability. A ~1,492‑year ISM cycle during the Holocene is also observed in this record, which is speculated to be linked to combined external (solar) and internal (AMOC) forcings. Comparisons with marine, ice-core, and other published records from the Central Ganga Plain reveal both consistencies and differences in millennial‑scale climate signals, underscoring the strong ocean–atmosphere influence on the ISM. The reconstructed monsoon–vegetation coupling indicates that shifts in the relative abundance of C₃ and C₄ plants were predominantly governed by changes in ISM intensity. For much of the record, C₃ and mixed C₃–C₄ vegetation dominated in the CGP, followed by a shift to C₄-dominated vegetation in the late Holocene (Meghalayan stage).