Diatom Inferred Sea Ice Conditions on the SE Greenland Shelf during the Last Millennium

Abstract:

Paleo sea ice conditions based on fossil diatom assemblages are reconstructed from sediment core MD99-2322 from the Kangerlussuaq Trough in order to investigate the variability of summer surface conditions on the SE Greenland shelf during the last millennium. Two diatoms based methods were used for the sea ice reconstructions; a) a qualitative method based on the statistically defined occurrence of diatom assemblages according to their relation to modern surface hydrography, and b) a quantitative method for May sea ice cover based on the Maximum Likelihood transfer function method. The reconstructions were generated with a subdecadal resolution for the time interval 870–1930 CE enabling to reconstruct the climate changes on the SE Greenland shelf with the highest resolution to date.

Diatoms show a pronounced influence of the sea ice cover in the area during the past 1130 years. Both qualitative diatom data (especially the occurrence of Fragilariopsis spp.) and the quantitative reconstruction for the May sea ice cover indicate the record sea ice cover for the first half of the Medieval Climate Anomaly (MCA) between 870 and 1030 CE. Results might indicate an increased sea ice export on the SE Greenland shelf during the onset of the warm climate anomaly. After the MCA, both Fragilariopsis spp. and the May sea ice reconstruction indicate a relatively stable sea ice conditions for the last 900 years of the record.