Radiocarbon Variability in the Western North Atlantic During the Last Deglaciation

Abstract

We present a detailed history of glacial to Holocene radiocarbon in the deep western North Atlantic from deep-sea corals and paired benthic-planktonic foraminifera. The deglaciation is marked by switches between radiocarbon-enriched and -depleted waters, leading to large radiocarbon gradients in the water column. These changes played an important role in modulating atmospheric radiocarbon. The deep-ocean record supports the notion of a bipolar seesaw with increased Northern-source deep-water formation linked to Northern Hemisphere warming and the reverse. In contrast, the more frequent radiocarbon variations in the intermediate/deep ocean are associated with roughly synchronous changes at the poles.

Abrupt climate change and collapse of deep-sea ecosystems

“…Even less is known about the biotic response to abrupt climate events. Furthermore, LSW, the source water for the core site, is highly unstable even over decadal timescales (43), and longer-term variability of deep-water masses at intermediate (Ͻ2,000 m) depths after the Last Glacial Maximum (LGM: Ϸ26-21 ka) are also complex (44)(45)(46)(47)(48). Bioturbation may also complicate the meiofaunal record from sediment cores.…”

Retreat of the Laurentide ice sheet tracked by the isotopic composition of Pb in western North Atlantic seawater during termination 1

“…For the Blake Ridge Fe-Mn oxyhydroxide samples published conventional 14 C ages (Keigwin, 2004;Robinson et al, 2005) obtained from planktonic foraminifera for cores 51GGC (n = 12) and 12JPC (n = 3) were transformed into calibrated ages using the marine radiocarbon age calibration Marine04 of Hughen et al (2004) assuming ∆R = 0. Calibrated ages of other depths in core 12JPC and 51GGC have been linearly interpolated between absolute age tie points.…”

“…The relatively radiogenic Nd isotope compositions (ε Nd ~ -10.5) observed in the deep core 12JPC until the Younger Dryas (Fig. 3) Core site 51GGC in 1790 m water depth was always located within Upper NADW / GNAIW (Boyle and Keigwin, 1987;Marchitto et al, 1998;McManus et al, 2004;Robinson et al, 2005;Came et al, 2008). It experienced high sedimentation rates throughout the deglaciation (Keigwin, 2004) Within the coarse-resolution Pb isotope record of crust 'Blake', there are no significant variations during the deglaciation (Fig.…”

Developments in Radiocarbon Technologies: From the Libby Counter to Compound-Specific AMS Analyses

“…They include the work of Lloyd Keigwin and his collaborators on late Pleistocene and Holocene climate change events (Keigwin 1996(Keigwin , 2004Keigwin and Pickart 1999;Keigwin et al 2005Keigwin et al , 2006Keigwin and Boyle 2008). Much attention is given by many researchers to the role of the North Atlantic and its important part in the overall ocean circulation and climate change during these time periods (Came et al 2003(Came et al , 2008Oppo et al 2003;Rasmussen et al 2003;McManus et al 2004;Robinson et al 2005;Lynch-Stieglitz et al 2007). The effect of solar cycles on North Atlantic climate was discussed by Gerard Bond and colleagues, using AMS measurements from ETH Zürich, Arizona, and NOSAMS (Bond et al 2001).…”