Biomarker Records of Environmental Shifts on the Labrador Shelf During the Holocene

<title xmlns:mml="http://www.w3.org/1998/Math/MathML">Abstract</title><p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en">The ultimate demise of the Laurentide Ice Sheet (LIS) and the preceding and succeeding oceanographic changes along the western Labrador Sea offer insights critically important to improve climate predictions of expected future climate warming and further melting of the Greenland ice cap. However, while the final disappearance of the LIS during the Holocene is rather well constrained, the response of sea ice during the resulting meltwater events is not fully understood. Here, we present reconstructions of paleoceanographic changes over the past 9.3 Kyr BP on the northwestern Labrador Shelf, with a special focus on the interaction between the final meltwater event around 8.2 Kyr BP and sea ice and phytoplankton productivity (e.g., IP₂₅, HBI III (Z), brassicasterol, dinosterol, biogenic opal, total organic carbon). Our records indicate low sea‐ice cover and high phytoplankton productivity on the Labrador Shelf prior to 8.9 Kyr BP, sea‐ice formation was favored by decreased surface salinities due to the meltwater events from Lake Agassiz‐Ojibway and the Hudson Bay Ice Saddle from 8.55 Kyr BP onwards. For the past ca. 7.5 Kyr BP sea ice is mainly transported to the study area by local ocean currents such as the inner Labrador and Baffin Current. Our findings provide new insights into the response of sea ice to increased meltwater discharge as well as shifts in atmospheric and oceanic circulation.</p>

Key Points: <list list-type="bullet"> <list-item> <p xml:lang="en">Sea ice on the Labrador Shelf mainly follows the solar insolation and meltwater input from the decaying Laurentide Ice Sheet</p></list-item> <list-item> <p xml:lang="en">Sea ice increased following the Lake Agassiz outburst and Hudson Bay Ice Saddle Collapse between 8.5 and 8.2 Kyr BP</p></list-item> <list-item> <p xml:lang="en">Low sea ice conditions during the Holocene Thermal Maximum were replaced by an increase following the Neoglacial cooling trend</p></list-item> </list> </p>

Ocean Frontier Institute

NSERC

https://doi.org/10.4095/221564

https://doi.org/10.1594/PANGAEA.949244

https://doi.org/10.5281/zenodo.8247131

https://doi.org/10.1594/PANGAEA.949065

https://doi.org/10.1594/PANGAEA.949056