Journal article Open Access

Holocene ocean conditions off the Zachariae Isstrøm, Northeast Greenland

Davies, J.; Mathiasen, A.M.; Kristiansen, K.; Hansen, K.E.; Wacker, L.; Alstrup, A.K.O.; Munk,O.; Pearce, C.; Seidenkrantz, M.-S.

The melting of marine terminating glaciers in Northeast Greenland is a visible sign that our climate is
changing. This melt has been partly attributed to changes in oceanic heat fluxes, particularly warming of
Atlantic Water (AW). Yet our understanding of the interaction between glaciers and the ocean is limited
by the length of instrumental records. Here, we present a multi-proxy study (benthic foraminifera assemblages,
CT scans, grain size, XRF, and stable isotope data) on core DA17-NG-ST08-092G, located 90 km
east of the Northeast Greenland Ice Stream (NEGIS). Whilst the exact timing of deglaciation is uncertain,
it is certain to have occurred at least as early as 12.5 ka cal BP, and likely before 13.4 ka cal BP. The inflow
of AW may have played a role in the seemingly early deglaciation on the Northeast Greenland continental
shelf. Following deglaciation, the site was overlain by an ice shelf, with AWand Polar Water (PW)
flowing beneath until 11.2 ka cal BP. The NEGIS briefly retreated westwards between 11.2 and 10.8 ka cal
BP before our site returned to glacier-proximal conditions dominated by colder subsurface water and
persistent AW flowing beneath (10.8e9.6 ka cal BP). Between 9.6 and 7.9 ka cal BP the NEGIS retreated
westwards; there was a continued presence of AWand PW at the site. A drastic shift in ocean circulation
occurred at 7.9 ka cal BP, with a decline in AW flow and dominance of PW flowing beneath perennial sea
ice. During the Late Holocene, there was return of AW and likely breakup of perennial sea ice.

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