Prolonged warming over the last ca. 11,700 cal years from the central Indian Core Monsoon Zone: Pollen evidence and a synoptic overview

Abstract

Paleopalynological records of 1.1 m deep lacustrine sediment profile from the central Indian Core Monsoon Zone (CMZ) have provided a prolonged warming trend over the last ca. 11,700 years. Palynological evidence suggests that between ca. 11,700 and 8500 cal yr BP, a mixed tropical deciduous forest occurred in the region under a warm and humid climate with good monsoon precipitation. The forest expanded into a dense mixed tropical deciduous forest since ca. 8500 cal yr BP to the present, under warm and relatively more humid climatic conditions with further increase in monsoon precipitation. This warm climatic phase represents the Holocene Climate Optimum (HCO) or Holocene Thermal Maximum (HTM). Prior to the initiation of the long warm period, an open vegetation occurred in the region between ca.14,100 and 11,700 cal yr BP, under a cool and dry climate, probably indicating reduced monsoon precipitation, and partially matching with the Older Dryas stadial. The present study provides insights into the vegetation dynamics and associated climatic changes in response to the Indian Summer Monsoon (ISM) variability over the last ~14.1 ka from a poorly understood area of the tropics in South Asia, where rainfall is essentially controlled by the ISM. In addition, an account of the asynchronous warming during the Holocene from the central Indian CMZ, as well as other tropical regions of the Indian sub-continent, has been presented here. Global contextualization of the Holocene warming has also been summarized in this communication.