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Younger Dryas and early Holocene climate in south Greenland inferred from oxygen isotopes of chironomids, aquatic Moss, and Moss cellulose

Puleo, Peter J.K.; Masterson, Andrew L.; Medeiros, Andrew S.; Schellinger, Grace; Steigleder, Regan; Woodroffe, Sarah; Osburn, Magdalena R.; Axford, Yarrow

Younger Dryas and early Holocene climate in south Greenland inferred from oxygen isotopes of chironomids, aquatic Moss, and Moss cellulose Thumbnail


Authors

Peter J.K. Puleo

Andrew L. Masterson

Andrew S. Medeiros

Grace Schellinger

Regan Steigleder

Magdalena R. Osburn

Yarrow Axford



Abstract

Ice core records have long indicated that the Younger Dryas began and ended with large, abrupt climate shifts over Greenland. Key climatic features remain unknown, including the magnitude of warming during the Younger Dryas-Holocene transition along with the seasonality and spatial variability of Younger Dryas climate changes across Greenland. Here, we use geochemical and paleoecological proxies from lake sediments at Lake N14 in south Greenland to address these outstanding questions. Radiocarbon dating and diatom assemblages confirm early deglaciation and isolation of Lake N14 before ∼13,600 cal yr BP, consistent with previous work. Oxygen isotope ratios (δ18O) of chironomid head capsules, bulk aquatic moss, and aquatic moss-derived cellulose are used to reconstruct oxygen isotopes of past lake water and annual precipitation. Oxygen isotope proxies indicate annual precipitation δ18O values increased by 5.9–7.7‰ at the end of the Younger Dryas. Following the Younger Dryas, moss and cellulose δ18O values show a clear decline in precipitation δ18O values of 2–3‰ from ∼11,540–11,340 cal yr BP that may correspond with the Preboreal Oscillation. Reconstructed precipitation δ18O values then gradually increased from 11,300–10,100 cal yr BP. All three aquatic organic materials register similar shifts in precipitation δ18O values over time, and they closely parallel the δ18O shifts observed in ice cores. This evidence strongly supports the utility of these methods for reconstructing lake water δ18O, and furthermore precipitation δ18O values where lake water reflects precipitation. The relatively large shift in isotopic composition of precipitation at Lake N14 suggests that shifts in temperature, precipitation seasonality, and/or moisture sources at the end of the Younger Dryas were even larger in south Greenland than they were in central Greenland, most likely because of the proximity to major changes in North Atlantic Ocean circulation. The annual air temperature change estimated at Lake N14 at the end of the Younger Dryas is also very large (∼18 ± 7 °C) compared to the summer warming previously inferred from chironomid species assemblages there (∼6 °C). This indicates that the strongest warming at the end of the Younger Dryas occurred in the winter season, consistent with past observations of intensified Younger Dryas seasonality at Lake N14 and elsewhere in Greenland.

Citation

Puleo, P. J., Masterson, A. L., Medeiros, A. S., Schellinger, G., Steigleder, R., Woodroffe, S., …Axford, Y. (2022). Younger Dryas and early Holocene climate in south Greenland inferred from oxygen isotopes of chironomids, aquatic Moss, and Moss cellulose. Quaternary Science Reviews, 296, Article 107810. https://doi.org/10.1016/j.quascirev.2022.107810

Journal Article Type Article
Acceptance Date Oct 6, 2022
Online Publication Date Oct 19, 2022
Publication Date Nov 15, 2022
Deposit Date Oct 20, 2022
Publicly Available Date Oct 20, 2023
Journal Quaternary Science Reviews
Print ISSN 0277-3791
Electronic ISSN 1873-457X
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 296
Article Number 107810
DOI https://doi.org/10.1016/j.quascirev.2022.107810
Public URL https://durham-repository.worktribe.com/output/1188398

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