14-3 Gradual Summer Warming Prior to the Pleistocene-Holocene Transition in New England (USA) Inferred from Chironomids and GDGTs

Session: Lake Sedimentary Records of Past Climate and Environment

Presenting Author:

Aidan Burdick

Authors:

Burdick, Aidan Warner¹, Gerstler, Kaitlyn Michelle², Stroup, Justin Sirico³, Randall, Anne⁴, Oswald, W. Wyatt⁵, Cwynar, Les C.⁶, Dieffenbacher-Krall, Ann C.⁷, McFarlin, Jamie M.⁸, Shuman, Bryan N.⁹, Kelly, Meredith A.¹⁰, Kitchel, Nathaniel R.¹¹, Axford, Yarrow¹²

(1) Department of Earth, Environmental, and Planetary Sciences, Northwestern University, Evanston, , (2) Department of Geology and Geophysics, University of Wyoming, Laramie, , (3) Department of Earth Sciences, Dartmouth College, Hanover, , (4) Department of Earth Sciences, Dartmouth College, Hanover, , (5) Marlboro Institute for Liberal Arts & Interdisciplinary Studies, Emerson College, Boston, , (6) Department of Biology, University of New Brunswick, Fredericton, , (7) School of Biology and Ecology, University of Maine, Orono, , (8) Department of Geology and Geophysics, University of Wyoming, Laramie, , (9) Department of Geology and Geophysics, University of Wyoming, Laramie, , (10) Department of Earth Sciences, Dartmouth College, Hanover, , (11) Department of Cultural, Environmental, and Global Studies, Salve Regina University, Newport, , (12) Department of Earth, Environmental, and Planetary Sciences, Northwestern University, Evanston, ,

Abstract:

The Pleistocene-Holocene transition (c. 11,700 cal yr BP) is among the most significant rapid warming events in the North Atlantic region during the late Quaternary. In New England and Atlantic Canada, this event was marked by large changes in archaeological records, forest composition, and isotopic proxies indicative of warming climate. However, a relative paucity of quantitative temperature records has left the magnitude of this last great warming in the region unresolved. Here, we present summer temperature reconstructions from across northern New England to address this gap, including three new records (two chironomid [midge] and one branched GDGT) and reexaminations of five previously published chironomid records from northern New Hampshire, Maine, and New Brunswick. Updating the published records using currently available training sets allows for modeling summer air temperature instead of water temperature and uses 10 times more modern calibration sites to improve the accuracy of reconstructions. Our analysis finds that summer warming across northern New England was spatially variable, ranging from 2-10 °C. Additionally, our new and temporally-well resolved reconstructions from central New Hampshire indicate that this warming was gradual, and about half of it took place during the latter half of the Younger Dryas chronozone (12,900 – 11,700 cal yr BP). This adds to a growing body of recently published work suggesting that the Younger Dryas chronozone may have consisted of multiple distinct phases related to changes in Atlantic Meridional Overturning Circulation (AMOC) strength. Additionally, these results suggest that the pattern of temperature change in northern New England may have differed from other North Atlantic sites (e.g., Greenland) due to variability in the spatial fingerprint of AMOC slowdown, regional atmospheric circulation, or the presence of the Laurentide Ice Sheet. These temperature reconstructions may also help resolve the presently poorly understood behavior of the Laurentide Ice Sheet and regional ice caps during the latest Pleistocene, along with gaps in the region’s archaeological record.

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