Arctic Ocean freshwater export and its relation to AMOC over the last two glacial cycles

2025/10/06 by Marc Zehnich, Robert F. Spielhagen, Henning A. Bauch +1 · 1 voice
Earth and Planetary Sciences · Environmental Science · #Geological Studies and Exploration #Geology and Paleoclimatology Research #Methane Hydrates and Related Phenomena

paper · doi:10.1016/j.quascirev.2025.109612

openalex publication_date 2025/10/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

Fram Strait, between NE Greenland and Svalbard, is the main passage for freshwater export from the Arctic Ocean (AO). Here we report results from the first high-resolution multiproxy study of a sediment record from 81°N in this Arctic Gateway to reconstruct the freshwater and environmental variability since ∼200 ka. Based on highly resolved stable isotope records from benthic and planktic foraminifers we link prominent isotopic events in marine isotope stages (MIS) 6-3 to times of strong freshwater input to the AO from the disintegration of circum-Arctic ice sheets and from the discharge of previously ice-dammed lakes in northern Eurasia. Additional short-term events point at the injection of low-salinity waters at intermediate depth along the NE Greenland continental margin, possibly caused by the release of sediment-laden, freshwater-enriched hyperpycnal flows on the shelf and upper continental margin. Changes in the deposition of foraminifers and coarse ice-rafted terrestrial debris at site PS93/016 document highly variable conditions in the NW Fram Strait with sedimentation from icebergs during times of large-scale glaciation around the Arctic and with other intervals dominated by sea ice. Foraminifer-rich sediments even suggest the development of seasonally open waters (polynyas) during certain periods. Four time intervals with a particularly strong and long-lasting freshwater export from the Arctic Ocean can be traced to the western Nordic Seas where modern deepwater formation occurs. The good temporal correlation of these intervals with weakenings of the deepwater circulation in the North Atlantic makes a strong case for a decisive role of Arctic freshwater export in the history of the global climate system of the last 200 ka, in particular as a trigger for instabilities of the Atlantic meridional overturning circulation.

Citations

• Age Dating and the Orbital Theory of the Ice Ages: Development of a High-Resolution 0 to 300,000-Year Chronostratigraphy
• Extended ¹⁴C Data Base and Revised CALIB 3.0 ¹⁴C Age Calibration Program
• Marine20—The Marine Radiocarbon Age Calibration Curve (0–55,000 cal BP)
• The Arctic has warmed nearly four times faster than the globe since 1979
• Physics-based early warning signal shows that AMOC is on tipping course
• Regional and global benthic δ 18 O stacks for the last glacial cycle
• The last Eurasian ice sheets – a chronological database and time‐slice reconstruction, DATED‐1
• A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ 18 O records

Discussions

• Did meltwater from circum-Arctic ice sheets trigger AMOC weakenings during past deglaciations? We think that we can present a convincing line of evidence, from the central Arctic to the North Atlantic [bsky, 4 points, 0 comments]

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• Dansgaard‐Oeschger cycles: Interactions between ocean and sea ice intrinsic to the Nordic seas
• Sea level rise and fall north of Greenland reorganize Arctic freshwater export to North Atlantic
• The large‐scale freshwater cycle of the Arctic