Abstract
Surface water characteristics of the Beaufort Sea have global climate implications during the last deglaciation and the Holocene, as (1) sea ice is a critical component of the climate system and (2) Laurentide Ice Sheet meltwater discharges via the Mackenzie River to the Arctic Ocean and further, to its outflow near the deep-water source area of the Atlantic Meridional Overturning Circulation. Here we present high-resolution biomarker records from the southern Beaufort Sea. Multi-proxy biomarker reconstruction suggests that the southern Beaufort Sea was nearly ice-free during the deglacial to Holocene transition, and a seasonal sea-ice cover developed during the mid-late Holocene. Superimposed on the long-term change, two events of high sediment flux were documented at ca. 13 and 11 kyr BP, respectively. The first event can be attributed to the Younger Dryas flood and the second event is likely related to a second flood and/or coastal erosion.
Highlights
Surface water characteristics of the Beaufort Sea have global climate implications during the last deglaciation and the Holocene, as (1) sea ice is a critical component of the climate system and (2) Laurentide Ice Sheet meltwater discharges via the Mackenzie River to the Arctic Ocean and further, to its outflow near the deep-water source area of the Atlantic Meridional Overturning Circulation
Core ARA04C/37 was recovered during the 2013 Araon Cruise ARA04C26 at the Beaufort Sea continental slope off the Mackenzie River (70°38.0212′N, 139° 22.0749′W; 1173 m) (Fig. 1), an area characterized by high sedimentation rates
The chronology of Core ARA04C/37 was constrained by accelerator mass spectrometry (AMS) 14C dating on calcareous foraminifera and, in the uppermost centimeters, excess 210Pb
Summary
Surface water characteristics of the Beaufort Sea have global climate implications during the last deglaciation and the Holocene, as (1) sea ice is a critical component of the climate system and (2) Laurentide Ice Sheet meltwater discharges via the Mackenzie River to the Arctic Ocean and further, to its outflow near the deep-water source area of the Atlantic Meridional Overturning Circulation. Causes of the abrupt climate change are not fully understood, special emphasis on the transition from the deglacial into the Holocene is of significance to understand the forcing mechanisms of the climate system In this context, the Arctic marginal seas characterized by strong seasonal variability in sea-ice cover, primary productivity, and terrigenous (riverine) input are very sensitive to environmental changes and of major importance for paleoclimate reconstructions. Since the drainage system was established during the late Wisconsinan (i.e., Marine Isotope Stage 2) as a result of glacial erosion, it was an outlet of glacial meltwater during the last deglaciation[15] During this period, a cold episode known as YD coincides with a significant reduction of AMOC caused by increased freshwater flux into the North Atlantic deepwater formation region[16]. Whereas the former is related to the YD flood event, the origin of the second event is related to a post-YD flood and/or coastal erosion
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