Climate and sea-ice development between 890 and 1660 CE in SW Greenland revealed by marine diatom studies

Abstract

This thesis presents the results of august Sea Surface Temperature reconstructions from marine diatom assemblages in samples from core Ga3-2 retrieved from Narsaq Sound, inside the Ikersuad fjord, South Greenland. The diatom samples provide a high-resolution (~30-year) reconstruction dating between 890 and 1660 CE (common era). The results show variable conditions with warm periods between 960 and 1010 CE and from 1370 to 1590 CE and cold periods from 890 to 960 CE and from 1010 to 1190 CE. This means cold summer Sea Surface temperatures during the Medieval Climate anomaly and warm temperatures during the Little Ice age. These results are compared to other records from the area, including diatom assemblages from other cores and temperature reconstructions from ice cores, as well as other sea temperature proxies like foraminiferal assemblages or alkenones from haptophyte algae. The comparisons show a complex relation between different proxies and indicate an opposite summer temperature trend between the Northeast Atlantic and South Greenland, probably linked to heat transport by the North Atlantic Current and its two branches, the Northwest Atlantic Current and the Irminger Current.