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Abstract. During the Last Glacial Period (LGP), Greenland experienced approximately 30 abrupt warming phases, known as Dansgaard–Oeschger (D–O) events, followed by cooling back to baseline glacial conditions. Studies of mean climate change across warming transitions reveal indistinguishable phase offsets between shifts in temperature, dust, sea salt, accumulation, and moisture source, thus preventing a comprehensive understanding of the “anatomy” of D–O cycles (Capron et al., 2021). One aspect of abrupt change that has not been systematically assessed is how high-frequency interannual-scale climatic variability surrounding centennial-scale mean temperature changes across D–O transitions. Here, we utilize the East Greenland Ice-core Project (EGRIP) high-resolution water isotope record, a proxy for temperature and atmospheric circulation, to quantify the amplitude of 7–15-year isotopic variability for D–O events 2–13, the Younger Dryas, and the Bølling–Allerød. On average, cold stadial periods consistently exhibit greater variability than warm interstadial periods. Most notably, we often find that reductions in the amplitude of the 7–15-year band led abrupt D–O warmings by hundreds of years. Such a large phase offset between two climate parameters in a Greenland ice core has never been documented for D–O cycles. However, similar centennial lead times have been found in proxies for Norwegian Sea ice cover relative to abrupt Greenland warming (Sadatzki et al., 2020). Using HadCM3, a fully coupled general circulation model, we assess the effects of sea ice on 7–15-year temperature variability at the EGRIP. For a range of stadial and interstadial conditions, we find a strong relationship in line with our observations between colder simulated mean temperature and enhanced temperature variability at the EGRIP location. We also find a robust correlation between year-to-year North Atlantic sea ice fluctuations and the strength of interannual-scale temperature variability at EGRIP. Together, paleoclimate proxy evidence and model simulations suggest that sea ice plays a substantial role in high-frequency climate variability prior to D–O warming. This provides a clue about the anatomy of D–O events and should be the target of future sea ice model studies. 

This data set is part of a joint international effort for the East GReenland Ice-core Project (EGRIP), which has retrieved an ice core by drilling through the Northeast Greenland Ice Stream (NEGIS, 75.63°N (North), 35.98°W (West)). Ice streams are responsible for draining a significant fraction of the ice from the Greenland Ice Sheet (GIS), and the project was developed to gain new and fundamental information on ice stream dynamics, thereby improving the understanding of how ice streams will contribute to future sea-level change. The drilled core also provides a new record of past climatic conditions from the northeastern part of the GIS. The project has many international partners and is managed by the Centre for Ice and Climate, Denmark with air support carried out by US ski-equipped Hercules aircraft managed through the US (United States) Office of Polar Programs, National Science Foundation. As of May 2022, approximately 2099.2 m (meters) of ice core have been recovered from the combined efforts of drilling operations in 2017, 2018, and 2019. Here we present records of stable isotopes of oxygen and hydrogen from 21.5 meters to 2120.7 m depth. Bedrock is estimated to be at a depth of approximately 2550 m; the remaining ice is expected to be recovered in the 2022 and 2023 field seasons. The data product presented here is supported by the National Science Foundation project: Collaborative Research: The fingerprint of abrupt temperature events throughout Greenland during the last glacial period. Award # 1804098. 

This data set is part of a joint international effort for the East GReenland Ice-core Project (EGRIP), which has retrieved an ice core by drilling through the Northeast Greenland Ice Stream (NEGIS, 75.63°N (North), 35.98°W (West)). Ice streams are responsible for draining a significant fraction of the ice from the Greenland Ice Sheet (GIS), and the project was developed to gain new and fundamental information on ice stream dynamics, thereby improving the understanding of how ice streams will contribute to future sea-level change. The drilled core also provides a new record of past climatic conditions from the northeastern part of the GIS. The project has many international partners and is managed by the Centre for Ice and Climate, Denmark with air support carried out by US ski-equipped Hercules aircraft managed through the US (United States) Office of Polar Programs, National Science Foundation. As of May 2022, approximately 2099.2 m (meters) of ice core have been recovered from the combined efforts of drilling operations in 2017, 2018, and 2019. Here we present records of stable isotopes of oxygen and hydrogen from 21.5 meters to 2120.7 m depth. Bedrock is estimated to be at a depth of approximately 2550 m; the remaining ice is expected to be recovered in the 2022 and 2023 field seasons. The data product presented here is supported by the National Science Foundation project: Collaborative Research: The fingerprint of abrupt temperature events throughout Greenland during the last glacial period. Award # 1804098.