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Abrupt climate changes during the last deglaciation have been well preserved in proxy records across the globe. However, one long-standing puzzle is the apparent absence of the onset of the Heinrich Stadial 1 (HS1) cold event around 18 ka in Greenland ice core oxygen isotope δ 18 O records, inconsistent with other proxies. Here, combining proxy records with an isotope-enabled transient deglacial simulation, we propose that a substantial HS1 cooling onset did indeed occur over the Arctic in winter. However, this cooling signal in the depleted oxygen isotopic composition is completely compensated by the enrichment because of the loss of winter precipitation in response to sea ice expansion associated with AMOC slowdown during extreme glacial climate. In contrast, the Arctic summer warmed during HS1 and YD because of increased insolation and greenhouse gases, consistent with snowline reconstructions. Our work suggests that Greenland δ 18 O may substantially underestimate temperature variability during cold glacial conditions.
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This content will become publicly available on February 24, 2026
Shifts in Greenland interannual climate variability lead Dansgaard–Oeschger abrupt warming by hundreds of years
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.
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- Award ID(s):
- 1804098
- PAR ID:
- 10647527
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Climate of the Past
- Date Published:
- Journal Name:
- Climate of the Past
- Volume:
- 21
- Issue:
- 2
- ISSN:
- 1814-9332
- Page Range / eLocation ID:
- 529 to 546
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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