P2C2: Evaluating North Pacific Hydroclimate during the Holocene Using the Denali Ice Core Archive

University Of Maine, Orono ME

Investigators

Abstract

This project broadly seeks to develop a Holocene-length hydroclimate record from the Mt. Hunter (Alaska) ice core archive and evaluate North Pacific hydroclimate variability in context with existing paleoclimate data and models. This project is motivated in part by recent observational and modeling studies that demonstrate a connection between Pacific multidecadal variability and Arctic warming during the early 20th century and since the 1970s. The impact of Pacific multidecadal variability on Arctic climate has considerable implications for sea ice extent and possible linkages between Arctic amplification, sea ice loss, and enhanced mid-latitude winter variability. Previous work on the Mt. Hunter ice core record demonstrates that the observed doubling of snow accumulation and 60-fold increase in summer melt during the industrial era (since the year 1850) is linked to Pacific multidecadal variability and is unique in the last millennium. The research seeks to confirm if the same drivers are relevant for the entire Holocene. Establishing how the Pacific-Arctic teleconnection responded during warm intervals and abrupt events outside of the instrumental period and last millennium would provide valuable insight into Earth system sensitivity. The researchers will combine several complementary techniques in different sections of the Mt. Hunter ice core archive, with specific focus on the bottom 20 meters of the twin 208-meter surface-to-bedrock cores. Preliminary radiogenic isotope (14-Carbon) analyses demonstrate that the basal ice is more than 10,000 years old. Specific project objectives include: 1) time scale development using additional 14-Carbon measurements, tephrochronology, laser ablation ICPMS measurements to extend annual layer counting, and a suite of glaciological models; 2) hydroclimate proxy development, including snow accumulation for regional moisture estimates (based on chronology and ice flow models), stable water isotopes for the integrated water cycle, and trace element chemistry for atmospheric dynamics; 3) integration with the new Holocene-length Mt. Hunter record with the existing North Pacific ice core array and other regional paleoclimate data; and 4) comparison of the new Holocene-length Mt. Hunter record with Earth system models. The potential Broader Impacts include a multi-faceted approach that includes support and mentoring of an early career scientist and a doctoral student in the context of international research cooperation. The researchers will collaborate with Colorado State University faculty and U.S. National Park Service faculty personnel to fabricate educational kits based on the Mt. Hunter ice core record that target grades 4-12 education in Alaska and Maine schools. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.