Past climatic changes using cave structures

What is it about?

This is the first thesis which encompasses a study of past precipitation pattern using six cave stalagmites from different parts of the Indian Himalaya.The stalagmites examined were KL-3 from Jammu and Kashmir; TCS and BR-1 from Himachal Pradesh; and DH-1, SA-1 and CH-1 from Uttarakhand. Based on the high resolution palaeoclimatic reconstruction( 35 U/th dates, 5 AMS dates, 1,500 samples for δ18O and δ13C values) was obtained for the duration of the Pleistocene- Holocene transition (16.2- 9.5 ka BP) and Mid Holocene- Present (ca. 4.0 ka BP- Present). Three major events were identified, e.g., Older Dryas (OD), Bølling-Allerød (BA) period and Younger Drays (YD) at ca. 14.3-13.9, 13.9-12.7 and 12.7-12.2 ka BP respectively. This is the first speleothem study in Indian Himalaya that shows a direct relationship of the past precipitation with collapse of civilization. The study showed a gradual reduction in the precipitation from 4 ka BP onwards for about a millennium with a peak arid period between 3.2-3.1 ka BP. In present records, the LIA (Little Ice Age) covers a time span of 1622 to 1820 AD during which the climate was wetter compared to that in the post-LIA period (1820-1950 AD). In addition this study supports that the WDs (Western Disturbances) contributed significantly in the total rainfall in the Himalaya region.

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Why is it important?

The Himalaya not only influences the rainfall pattern in India, but also obstructs the path of the cold winds coming from the north because of altitude and location. The Inner Asian high pressure systems and winter Westerlies are main components of the Himalayan climate and a combined impact of rainfall, latitude and altitude mainly affect the climate pattern. The region mainly experiences two seasons, i.e., summer (June to September) and winter (October to May). The Indian Summer Monsoon (ISM) decreases towards northwest India where Western Disturbances (WDs) play a major role in the annual precipitation. Therefore, the role of the WDs cannot be overlooked while using any archive or proxy for the past climatic changes in the Indian Himalaya. Taking this into account as well as knowing that the high resolution palaeoclimatic records are scarce from the Indian Himalaya, Anoop Kumar Singh was given an assignment on high resolution past climatic changes in selected sectors of the Indian Himalaya employing cave speleothems, particularly for the last ~15 ka period and undoubtedly the results should be very helpful to develop the models for ISM variability and WDs through an improved understanding of the monsoon-climate interaction.