A 100-year long record of alkenone-derived SST changes by Southeast Greenland
Résumé
Sediment core ER07 from Sermilik Fjord by Helheim Glacier in Southeast Greenland was analysed
for alkenones to document sea surface temperature (SST) changes over the past 100 years. The
alkenone SST values, ranging from 8 to 12°C, contrasts with colder values (0-4°C) obtained from
recent hydrographic surveys inside the fjord. We suggest that advection of allochtonous alkenones
produced in the warm Irminger Current waters circulating on the shelf likely accounts for this
difference. The temperature range of the alkenone-derived record is similar to in situ observations
of 8-11°C on the shelf just outside Sermilik Fjord, and its variability over the past 100 years
resembles the constructed variability over the shelf using remote instrumental data. This suggests
that oceanographic changes on the adjacent shelf are linked to regional changes of the Irminger
Current and the East Greenland Current. The subsurface water heat content has previously been
suggested as an important control on Greenland outlet glacier stability and underlined by an episode
of warm subsurface waters ~ 1940 concurrent with markedly increased calving and retreat of
Helheim Glacier. Our results therefore suggest that alkenone-derived SST time series from highsedimentation rate glacial fjords may provide a new approach for reconstruction of past changes of
shelf water properties and variability around Greenland.
Origine | Fichiers produits par l'(les) auteur(s) |
---|