Centennial‐to‐millennial‐scale periodicities of Holocene climate and sediment injections off the western Barents shelf, 75°N

Abstract

At the western continental margin of the Barents Sea, 75°N, hemipelagic sediments provide a record of Holocene climate change with a time resolution of 10-70 years. Planktic foraminifera counts reveal a very early Holocene thermal optimum 10.7-7.7 kyr BP, with summer sea surface temperatures (SST) of 8°C and a much enhanced West Spitsbergen Current. There was a short cooling between 8.8 and 8.2 kyr BP. In the middle and late Holocene summer, SST dropped to 2.5°-5.0°C, indicative of reduced Atlantic heat advection, except for two short warmings near 2.2 and 1.6 kyr BP. Distinct quasi-periodic spikes of coarse sediment fraction (with large portions of lithic grains, benthic and planktic foraminifera) record cascades of cold, dense winter water down the continental slope as a result of enhanced seasonal sea ice formation and storminess on the Barents shelf over the entire Holocene. The spikes primarily cluster near recurrence intervals of 400-650 and 1000-1350 years, when traced over the entire Holocene, but follow significant 885-/840-and 505-/605-year periodicities in the early Holocene. These non-stationary periodicities mimic the Be variability, which is a tracer of solar forcing. Further significant Holocene periodicities of 230, (145) and 93 years come close to the deVries and Gleissberg solar cycles.

Middle to late Holocene paleoproductivity reconstructions for the western Barents Sea: a model-data comparison

“…Similar PP rates (5 and 50 gC m -2 year -1 at R87 and PSh-5159N respectively) and low TOM supply as reported during the middle Holocene suggest ice-free, present-day-like oceanographic conditions with only marginal influence of sea ice related processes [48]. This inference is supported by a sea surface temperature reconstruction from the western Barents Sea margin indicating the absence of sea ice between 3000 and 1600 years BP [52]. Furthermore, it fits well with the continuous presence of the subpolar planktic foraminifer species Turborotalita quinqueloba off western Svalbard during the past 3000 years BP [74] suggesting persistent influence of Atlantic-derived water masses along the western Barents Sea margin and consequently limited southward extension of the MIZ.…”

“…The increase in PP rates in the north at about 1000 years BP corroborates an overall trend of increased influence of Atlantic-derived water masses in western Barents Sea surface waters [10,52]. Particularly at nearby MIZ location St.20, sustained AW inflow has influenced surface water conditions from ca.…”

Sub-decadal- to decadal-scale climate cyclicity during the Holsteinian interglacial (MIS 11) evidenced in annually laminated sediments

“…To date, its origin remains unclear; it is considered to be related to either solar forcing (Stuiver et al, 1995;Sarnthein et al, 2003) or changes in the North Atlantic thermohaline circulation (Stuiver and Braziunas, 1993;Chapman and Shackleton, 2000;Damon and Peristykh, 2000;Risebrobakken et al, 2003). No other centennial-scale cycles were identified in the Dethlingen record, e.g.…”

Atlantic Water advection vs. glacier dynamics in northern Spitsbergen since early deglaciation

“…The transition from the Pleistocene to the early Holocene, and especially the Holocene Thermal Maximum (HTM), when enhanced northward advection of Atlantic Water (AW; e.g. Sarnthein et al, 2003) and maximum insolation were recorded at high northern latitudes (Berger and Loutre, 1991), may help demonstrate ocean-glacier interactions under a fast warming trend, possibly comparable to the ongoing global warming.…”