Western tropical Pacific hydroclimate across four glacial cycles

Long, high-resolution, absolutely-dated records of past hydroclimate provide the unique opportunity to assess the relationships between a rich variety of past climate forcings and hydrological response. Here, we present the latest compilation of well-replicated stalagmite oxygen isotopic (d18O) records from Gunung Mulu Park, in northern Borneo, that stretches over the last 550,000 years. We focus on the timing and structure of stalagmite d18O variability during major climate transitions including glacial-interglacial terminations as well as a wide variety of sub-orbital climate change events noted in paleoclimate records from both the tropics and extratropics. Ultra-high-resolution timeseries of stalagmite d18O from the Holocene as well as 74kybp, across the Toba super-eruption, document appreciable changes in the character of interannual to decadal-scale variability that may contribute to observed stalagmite d18O variations on millennial to orbital timescales. We employ a suite of climate model output, as well as results from modern-day rainfall d18O monitoring, to investigate the dynamical drivers of observed spring/fall precessional insolation forcing control on Borneo stalagmite d18O.