A 2600-yr multiproxy record for climate and vegetation reconstruction along the Mahanadi River delta, east coast of India

Understanding the impact of climate change on the vegetation cover in the past is crucial for predicting the future warming scenario and its consequences. The present study integrates biotic (palynological analysis) and abiotic proxy (sediment chemistry, clay mineral assemblages and grain size end member (EM) analysis) records in a chronologically constrained sedimentary sequence from the southeastern part of the Mahanadi River delta to reconstruct the hydroclimate since 2600 years. The Mahanadi delta sediments are primarily derived from felsic rock source possibly composed of granites or granulites. The dominance of herbaceous taxa, high aridity index and deposition of fine grain (EM1) sediment possibly suggest a relatively cold and dry climate in the study region during similar to 2600-2100 cal yr BP corresponding to the Iron Age Cold Period (IACP). Presence of diverse mangrove and tree taxa, deposition of coarser sediment (EM3) and relatively high abundance of secondary clay minerals possibly indicate high precipitation associated with the Roman Warm Period (RWP, similar to 2100-1800 cal yr BP). A decline in mangroves, dominance of herbaceous taxa and high deposition of fine grain (EM2) sediment from similar to 1800 to 1300 cal yr BP may indicate a relatively drier climate coinciding with the Dark Age Cold Period (DACP). High moisture index and an increased value of Rb/Sr during similar to 1300 cal yr BP may suggest a wet phase with the onset of the Medieval Climatic Anomaly (MCA) and later shifted to an arid climate during similar to 1100-800 cal yr BP. After similar to 800 cal yr BP, a sharp decline in all weathering indices and vegetation cover, dominance of illite indicates a relatively dry climate which could mark the Little Ice Age (LIA, similar to 800-300 cal yr BP). A small increase in the terrestrial flux, as well as the weathering indices after similar to 300 cal yr BP, may suggest the onset of recent warming.

Automated summary

Understanding the impact of climate change on vegetation cover in the past is important to predict future scenarios. A study in the Mahanadi River delta reconstructed the hydroclimate over the past 2600 years using biotic and abiotic proxy records. The results showed variations in climate, including periods of cold and dry climate, increased precipitation, and dry periods.