Correlating organic carbon burial with regional climate variability: the past two centuries tale from Sermilik fjord, Southeast Greenland

Abstract

As the Arctic undergoes ‘Atlantification’ and warms at a faster rate than lower latitudes, dramatic physical and biological changes are occurring in the ocean, atmosphere and cryosphere systems. This project focusses on fjord environments connected to the Greenland Ice Sheet, which has recently experienced a significant and rapid loss of ice attributed primarily to changes in the surface mass balance and increased iceberg calving from tidewater glaciers. Helheim glacier, at the head of Sermilik fjord is one of the largest outlet glaciers in Southeast Greenland and to better understand its dynamic interplay with climate forcing and the marine ecosystem downstream this study investigates sediment core ER11-24S, recovered from the 558 m water depth c. 35 km from the calving margin. Total organic carbon (TOC) throughout the core is relatively low and ranges from 0.09 to 0.14 wt.%. To interrogate the composition, trace the source and ultimately understand the fate of the organic matter, a suite of bulk organic geochemical proxy are analysed and reveal a clear fingerprint of terrestrial origin. A correlation of TOC and the regional atmospheric circulation system, the North Atlantic Oscillation (NAO), highlights peaks in TOC occurred during positive NAO phases and lows occurred during negative phases. We propose that over the last two centuries the NAO has exerted a dominant influence on organic carbon burial within Sermilik fjord and that climatic conditions associated with negative NAO phases have diluted the TOC signal in the fjord sediments during these times.