Holocene thermal maximum in the western Arctic (0-180°W)

D. S. Kaufman*, T. A. Ager, N. J. Anderson, P. M. Anderson, J. T. Andrews, P. J. Bartlein, L. B. Brubaker, L. L. Coats, L. C. Cwynar, M. L. Duvall, A. S. Dyke, M. E. Edwards, W. R. Eisner, K. Gajewski, A. Geirsdóttir, F. S. Hu, A. E. Jennings, M. R. Kaplan, M. W. Kerwin, A. V. LozhkinG. M. MacDonald, G. H. Miller, C. J. Mock, W. W. Oswald, B. L. Otto-Bliesner, D. F. Porinchu, K. Rühland, J. P. Smol, E. J. Steig, B. B. Wolfe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

631 Citations (Scopus)

Abstract

The spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0-180°W; north of ∼60°N). Paleoclimate inferences based on a wide variety of proxy indicators provide clear evidence for warmer-than-present conditions at 120 of these sites. At the 16 terrestrial sites where quantitative estimates have been obtained, local HTM temperatures (primarily summer estimates) were on average 1.6±0.8°C higher than present (approximate average of the 20th century), but the warming was time-transgressive across the western Arctic. As the precession-driven summer insolation anomaly peaked 12-10ka (thousands of calendar years ago), warming was concentrated in northwest North America, while cool conditions lingered in the northeast. Alaska and northwest Canada experienced the HTM between ca 11 and 9ka, about 4000yr prior to the HTM in northeast Canada. The delayed warming in Quebec and Labrador was linked to the residual Laurentide Ice Sheet, which chilled the region through its impact on surface energy balance and ocean circulation. The lingering ice also attests to the inherent asymmetry of atmospheric and oceanic circulation that predisposes the region to glaciation and modulates the pattern of climatic change. The spatial asymmetry of warming during the HTM resembles the pattern of warming observed in the Arctic over the last several decades. Although the two warmings are described at different temporal scales, and the HTM was additionally affected by the residual Laurentide ice, the similarities suggest there might be a preferred mode of variability in the atmospheric circulation that generates a recurrent pattern of warming under positive radiative forcing. Unlike the HTM, however, future warming will not be counterbalanced by the cooling effect of a residual North American ice sheet.

Original languageEnglish
Pages (from-to)529-560
Number of pages32
JournalQuaternary Science Reviews
Volume23
Issue number5-6
DOIs
Publication statusPublished - Mar 2004

Bibliographical note

Funding Information:
The PARCS-HTM Working Group meeting at the National Center for Atmospheric Research in Boulder, CO was supported by the US National Science Foundation Arctic System Science Program. The participation of the PARCS Data Manager (M. Duvall) and Science Management Officer (L. Coats) was funded through grant NSF-OPP-0218785. Reviews by A. Werner and an anonymous referee improved the paper.

Funding Information:
Contribution by PARCS (Paleoenvironmental Arctic Sciences), a research initiative sponsored by the US National Science Foundation. PARCS Holocene Thermal Maximum Working Group members and author affiliations listed in Appendix A.

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