An overview of Holocene monsoon variability of Sri Lanka and its association with Indian subcontinent climate records

Located in the core of the Indian monsoon domain, Sri Lanka has a classic tropical monsoonal climate, thus making it an ideal platform for paleoclimatic investigations. During past decades, extensive studies have been carried out to explore the Indian Ocean monsoon variability across different time scales including in Sri Lanka. This review synthesized a comprehensive picture of the paleo-monsoon variability of Sri Lanka during the Holocene and compared it with the regional records from the Indian monsoon regime. Available paleoclimate information indicated that the early Holocene is characterized by a strong monsoon phase in Sri Lanka. This enhanced monsoon activity phase was followed by a weak monsoon phases around 8.0 kyr BP. Mid-Holocene was identified as a semi-arid to arid or a period with decreased monsoon activity. The late Holocene showed a highly variable climate with a large spatial variability across Sri Lanka. These observations are almost consistent with the climatic records of the Indian monsoon regime. Dissimilarities in the timing of onset and withdrawal of monsoons were also noted in different geographical localities in Sri Lanka that are possibly due to localized responses of the climate system. Paleoclimate records from Sri Lanka revealed that summer and winter monsoons behaved mostly in a similar way, implying similar forcing mechanisms. Despite the contrasting differences among regional records across shorter time scales, the monsoon climate of Sri Lanka during the Holocene has varied coherently with the climate of other regions of the Indian monsoon domain including the Indian subcontinent, the Bay of Bengal, Northern Andaman Sea, Eastern, and Western Arabian Sea, Northern and Southern Oman, Yemen and as far as some locations from China.