Coeval Holocene Stalagmites Record Multi‐Centennial Climate Variability and Drought in the Northern Rocky Mountains, USA

Abstract The El Niño Southern Oscillation and Pacific Decadal Oscillation (PDO) are key drivers of cool‐season precipitation variability in the western United States (US), including the Rocky Mountains. Together, they help modulate the north‐south “precipitation dipole,” a regional climate pattern operating on multi‐decadal timescales leading to dry conditions north of 40°N latitude when the south is wet, and vice versa. We investigate the natural evolution of this climate pattern using two precisely‐dated (5900 years ago to present), multi‐proxy, coeval stalagmite records of hydroclimate from Titan Cave, Wyoming, located just north of the modern‐day dipole transition zone. Consistent trace element and stable isotope records from the two stalagmites reflect the amount and seasonality of regional precipitation, documenting decreased winter snowfall and dry conditions over multi‐decadal intervals characterized by the warm phase of the PDO and more frequent and stronger El Niño events.