Extended Cave Drip Water Time Series Captures the 2015–2016 El Niño in Northern Borneo
Shelby A Ellis, K. M. Cobb, J. W. Moerman, J. W. Partin, A. Landry Bennett, Jenny Malang, Hein Gerstner, Andrew Alek Tuen
Abstract
Abstract Time series of cave drip water oxygen isotopes (δ 18 O) provide site‐specific assessments of the contributions of climate and karst processes to stalagmite δ 18 O records employed for hydroclimate reconstructions. We present ~12‐year‐long time series of biweekly cave drip water δ 18 O variations from three sites as well as a daily resolved local rainfall δ 18 O record from Gunung Mulu National Park in northern Borneo. Drip water δ 18 O variations closely match rainfall δ 18 O variations averaged over the preceding 3–18 months. We observe coherent interannual drip water δ 18 O variability of ~3‰ to 5‰ related to the El Niño–Southern Oscillation (ENSO), with sustained positive rainfall and drip water δ 18 O anomalies observed during the 2015/2016 El Niño. Evidence of nonlinear behavior at one of three drip water monitoring sites implies a time‐varying contribution from a longer‐term reservoir. Our results suggest that well‐replicated, high‐resolution stalagmite δ 18 O reconstructions from Mulu could characterize past ENSO‐related variability in regional hydroclimate.