A multi-proxy reconstruction of climate during the late-Pleistocene to early Holocene transition in the northeastern, USA

Abstract

A multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species’ environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation.

Weak precipitation δ2H response to large Holocene hydroclimate changes in eastern North America

“…The reconstructions show three distinctive hydroclimate features: (1) a wet Younger-Dryas interval (12.9-11.7 ka), more prominent at the northern sites (NY and VT) than at the southern or coastal sites (PA and MA), which is consistent with other lines of evidence for increased precipitation during this time interval in the region(Grigg et al, 2021); (2) a region-wide dry early Holocene (11.7-8.2 ka); and (3) a progressive increase in precipitation during the mid-to late Holocene (>6 ka-present) particularly in Massachusetts near the North Atlantic coast and not in Vermont. The entire region has seen a reduction in the warm/cold season ratio of precipitation such that seasonal precipitation inputs are close to being equal during the late Holocene.…”

A Holocene pollen-inferred climate reconstruction for Vermont, USA

“…The Twin Ponds and Knob Hill Pond pollen records were compared by examining the timing of six individual pollen events representing previously described shifts in the regional vegetation (Oswald and Foster, 2011;Oswald et al, 2018;Grigg et al, 2021).…”

“…High percentages of Quercus and Pinus starting at ca. 10.5 cal ka BP indicate the warmest and driest conditions of the Holocene in VT and in other northern records (Spear, 1989;Whitehead et al, 1990;Spear et al, 1994;Grigg et al, 2021). The second shift occurs after 8.5 cal ka BP, when forests became dominated by mesic taxa, including Tsuga canadensis, Fagus grandifolia, and Betula (Ford, 1990;Oswald and Foster, 2011).…”

“…Existing Holocene pollen data from VT show several prominent shifts in vegetation that coincide with orbital and regional climate forcing (Ford, 1990; Oswald et al, 2018; Grigg et al, 2021). The first shift occurred during the earliest Holocene (11.7–9.0 cal ka BP) with the transition from Picea - to Pinus -dominated forests following the Younger Dryas cooling event (YD; 12.8–11.5 cal ka BP).…”

“…The first shift occurred during the earliest Holocene (11.7–9.0 cal ka BP) with the transition from Picea - to Pinus -dominated forests following the Younger Dryas cooling event (YD; 12.8–11.5 cal ka BP). This transition in northern forests included a sequence of short-lived mixed boreal forest types (Spear, 1989; Ford, 1990; Whitehead et al, 1990; Spear et al, 1994; Oswald et al, 2018; Grigg et al, 2021). Deglacial, no-analog vegetation communities in the Great Lakes have been shown to closely track rapid warming (Fastovich et al, 2020a).…”