Northeast Indian stalagmite records Pacific decadal climate change: Implications for moisture transport and drought in India

Abstract

Two types of El Niño events are distinguished by sea surface temperature (SST) anomalies centered in the central or eastern equatorial Pacific. The Central Pacific El Niño events (CP‐El Niño) are more highly correlated with weakening of the central Indian Summer Monsoon and linked to decadal Pacific climate variability. We present a 50 year, subannually resolved speleothem δ18O record from northeast India that exhibits a significant correlation with northern Pacific decadal variability and central equatorial Pacific SSTs. Accordingly, we suggest that δ18O time series in similar northeast Indian speleothems are effective tools for investigating preinstrumental changes in Pacific climate, including changes in El Niño dynamics. In contrast to central India, rainfall amounts in northeast India are relatively unaffected by El Niño. However, back trajectory analysis indicates that during CP‐El Niño events moisture transport distance to northeast India is reduced, suggesting that variations in moisture transport primarily control δ18O in the region.

Timing and Structure of the 4.2 ka BP Event in the Indian Summer Monsoon Domain from an Annually-Resolved Speleothem Record from Northeast India

“…18 O values of our records are used to refer to strong and weak monsoons, respectively, consistent with a number of previous studies (e.g., Dayem et al, 2010;Breitenbach et al, 2010;Sinha et al, 2011;Cheng et al, 2012;Sinha et al, 2011;Berkelhammer et al, 2012;Breitenbach et al, 2015;Myers et al, 2015, Dutt et al, 2015Cheng 160 et al, 2012;Kathayat et al, 2016;Kathayat et al, 2017).…”

“…The temperature variations in the cave are 140 small (18.0-18.5°C) and close to the mean annual temperature of the area (Breitenbach et al, 2010 and. A 3-year monitoring study in Mawmluh Cave (Breitenbach et al, 2010) (Breitenbach et al, 2010 andBerkelhammer et al, 2012;Myers et al, 2015;Dutt et al, 2015).…”

Rapid Drying of Northeast India in the Last Three Decades: Climate Change or Natural Variability?

“…The Pacific decadal oscillation (PDO), a dominant pattern of North Pacific SST (120 • E to 120 • W to 20-60 • N), is also known to have a prominent year-to-year as well as interdecadal variability (Krishnamurthy & Krishnamurthy, 2014;Mantua et al, 1997). Speleotherm record of 50 years from NEI also suggested a significant relationship between monsoon rainfall and PDO (Myers et al, 2015). However, PDO is not purely a mode of its own but also reinforced with several natural variability including ENSO (Newman et al, 2016).…”

Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America

“…Griggs et al, 2017) or speleothems (e.g. Myers et al, 2015) from western North America may assist in determining the role of El Niño flavor in structuring hydroclimatic variability across this region during the mid-Holocene.…”