A 2000 Year Multi-Proxy Evidence of Natural/Anthropogenic Influence on Climate from the Southwest Coast of India

Abstract

The last millennium climate reconstructions are complex and limit our understanding of the mechanisms behind environmental and climate variability. We present multi-proxy centennial-scale records from the Cherai, southwest India. The last 2000 cal yr AD record suggests a complex environmental condition that prevailed at the depositional site augmenting the role of natural as well as anthropogenic agents. Increased elemental variations and indices values indicate stronger weathering, presumably wetter conditions and intense precipitation. Provenance studies suggest diverse sources and the main composition fall close to the Charnockite and Gneissic composition. Multi-proxy data suggests that a shift towards wetter climatic conditions, which occurred from 910 to 1230 cal yr AD. The core also records a shift towards the drier conditions that started around 1230 cal yr AD with a loss in vegetation diversity. The pollution load index values suggest that the overall study area falls in moderate contamination levels, which are also substantiated with the diatom data indicating human influence in the natural habitat during the deposition time. The present study reveals that the enhanced Cd and As concentration is due to strong anthropogenic influence. We compared the multi-proxy record with other continental and marine palaeoclimatic records to explore global and/or regional trends in climate variability during the last 2000 years.

Keywords

estuaries / monsoon / provenance / vegetation / clmate / contamination

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