Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Abstract

The first moderate‐ to high‐resolution Holocene marine stable isotope record from the nearshore Antarctic continental shelf (Ocean Drilling Program (ODP) Hole 1098B) suggests sensitivity of the western Antarctic Peninsula hydrography to westerly wind strength and El Niño‐Southern Oscillation (ENSO)‐like climate variability. Despite proximity to corrosive Antarctic water masses, sufficient CaCO3 in Palmer Deep sediments exists to provide a high‐quality stable isotopic record (especially in the late Holocene). Coherence of benthic foraminifer δ18O, δ13C, sedimentologic, and CaCO3 fluctuations suggests that rapid (<20 years) Palmer Deep bottom water temperature fluctuations of 1°–1.5°C are associated with competitive interactions between two dominant oceanographic/climatic states. An abrupt shift from a warmer, stable Upper Circumpolar Deep Water (UCDW) state to a cooler, variable shelf water state occurred at ∼3.6 ka. Palmer Deep bottom waters oscillated between UCDW and shelf water‐dominated states between ∼3.6 and 0.05 ka. Cool shelf water intervals correlate with Neoglacial events, the most recent and largest being the Little Ice Age (LIA; ∼0.7–0.2 ka). Similarities between Palmer Deep and global Holocene records and the rapidity of inferred bottom water fluctuations suggest that western Antarctic Peninsula shelf hydrography has not been controlled by thermohaline reorganizations but by variable strength and/or position of the Southern Hemisphere westerly wind field. We suggest that these atmospheric perturbations may have originated in the low‐latitude tropical Pacific.

Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

“…Sediment cores from the Palmer Deep have marked variability in the silt to clay ratio and in micro-fossil composition (Leventer et al 1996). These changes in productivity and phytoplankton species composition are linked to the extent of glaciation and long-scale variability in the dynamics of the ACC and the flux of warm water of the UCDW onto the continental shelf (Shevenell & Kennett 2002, Warner & Domack 2002. How these global and regional climate forcings affect extant ecological interactions is a subject of great interest.…”

Mechanisms of Holocene palaeoenvironmental change in the Antarctic Peninsula region

“…Like the MWP, evidence for an LIA in AP proxy records is patchy but it is recognized in the Palmer Deep for the period 700 to 150 cal yr BP with more persistent sea ice and colder sea-surface and bottom-water conditions corresponding with local glacial advances (Domack et al, 1995;2003b;Shevenell et al, 1996;Leventer et al, 1996Leventer et al, , 2002Shevenell and Kennett, 2002;Taylor and Sjunneskog, 2002;Sjunneskog and Taylor, 2002;Warner and Domack, 2002). Various outlet glaciers or ice shelves such as Rotch Dome, Livingston Island (Björck et al, 1996a) and the Müller Ice Shelf (Domack et al, 1995) …”

“…Pope and Anderson, 1992;Pudsey et al, 1994;Ó Cofaigh et al, 2001;2005a;Anderson et al, 2002;Heroy and Anderson, 2005;Evans et al, 2005); palaeoceanographic changes such as surface water productivity (Leventer et al, 2002;Sjunneskog and Taylor, 2002;Taylor and Sjunneskog 2002); the proximity and stability of ice shelves and glaciers (Domack et al, 1995;Pudsey and Evans, 2001;Brachfeld et al, 2003); duration or extent of sea ice (Leventer et al, 1996;Gersonde et al, 2003) the influx of meltwater and terrigenous sediments (Domack et al, 1994), and clues to the behaviour of ocean currents such as the ACC or distribution of water masses such as CDW (Howe and Pudsey, 1999;Shevenell and Kennett, 2002) or Antarctic Bottom Water (AABW) (Anderson, 1999).…”

Holocene variation in the Antarctic coastal food web: linking δD and δ13C in snow petrel diet and marine sediments

“…Among factors that might directly affect food-web δ 13 C, past variation in coastal Antarctic dissolved inorganic 13 C can be inferred from analysis of carbonate (foraminifera shells) found in 14 C-dated sediments to 8450 cal yr BP (Shevenell & Kennett 2002). The magnitude of this variation, ~1 ‰, although also influenced by primary productivity and bottom water formation (Mackensen et al 1994), is a significant fraction of the variation (1.8 ‰) seen in the mumiyo record over the same period (with the caveat related to sample size noted below).…”