Unexpectedly High Accumulation Rates in the 2022 Mt. Logan Ice Core Reveal Warm‐Season Drivers of Precipitation Variability

Abstract Ice cores from Mt. Logan, the second highest peak in North America located in the St. Elias mountains in southwest Yukon, Canada, have provided conflicting accumulation records, thus the hydroclimate response to changing atmospheric conditions in the highest elevation regions is not well constrained. Here, we present the accumulation record from the new 325 m Mt. Logan ice core drilled at 5,334 m asl on the summit plateau in May 2022. Multi‐parameter annual layer counting, confirmed with radionuclide and volcanic tephra measurements, extends to 1911 CE, associated with a depth of 257 m. The thinning‐corrected annual accumulation record reveals an average rate of 3.0 m water equivalent per year (m weq a −1 ) from 1912 to 2020 CE, greater than six times higher than the previous estimate of ∼0.41 m weq a −1 from the 2002 Mt. Logan Prospector Russell Col core. Correlation analysis between the annual accumulation record and regional climate data sets (e.g., Japanese 55‐year Reanalysis, weather stations) reveal a strong positive relationship with warm‐season total precipitable water and temperature. Thus, we suggest interdecadal precipitation variability on Mt. Logan is at least partially driven by warm‐season atmospheric water vapor loading, potentially related to atmospheric temperature responses associated with the warm‐season Alaska Blocking Index. Further, the record reveals a statistically significant increase in accumulation of 0.13 m weq per decade since 1970. These results reveal a drastically different Mt. Logan ice core record and provide a new warm‐season perspective on drivers of high‐elevation accumulation variability in the North Pacific.