Low‐frequency storminess signal at Bermuda linked to cooling events in the North Atlantic region

Abstract

North Atlantic climate archives provide evidence for increased storm activity during the Little Ice Age (150 to 600 calibrated years (cal years) B.P.) and centered at 1700 and 3000 cal years B.P., typically in centennial-scale sedimentary records. Meteorological (tropical versus extratropical storms) and climate forcings of this signal remain poorly understood, although variability in the North Atlantic Oscillation (NAO) or Atlantic Meridional Overturning Circulation (AMOC) are frequently hypothesized to be involved. Here we present records of late Holocene storminess and coastal temperature change from a Bermudian submarine cave that is hydrographically circulated with the coastal ocean. Thermal variability in the cave is documented by stable oxygen isotope values of cave benthic foraminifera, which document a close linkage between regional temperature change and NAO phasing during the late Holocene. However, erosion of terrestrial sediment into the submarine cave provides a "storminess signal" that correlates with higher-latitude storminess archives and broader North Atlantic cooling events. Understanding the driver of this storminess signal will require higher-resolution storm records to disentangle the contribution of tropical versus extratropical cyclones and a better understanding of cyclone activity during hemispheric cooling periods. Most importantly, however, the signal in Bermuda appears more closely correlated with proxy-based evidence for subtle AMOC reductions than NAO phasing.

Climate control on late Holocene high-energy sedimentation along coasts of the northeastern Atlantic Ocean

“…to the Bond cycle 0 (Bond et al, 2001). Steepening of the meridional temperature gradient during the LIA is frequently invoked as a plausible mechanism needed to trigger stronger storms in the North Atlantic Ocean at that time (Dezileau et al, 2011;Lamb and Frydendahl, 1991;Trouet et al, 2012), in possible conjunction with low-frequency changes in sea surface temperature driving tropical cyclogenesis (van Hengstum et al, 2015).…”

Anthropogenic infilling of a Bermudian sinkhole and its impact on sedimentation and benthic foraminifera in the adjacent anchialine cave environment

“…In addition, bulk organic matter content decreased from 12 to 5% between 12 to 9 cm, before immediately returning to 12%, from 9 cm to the coretop. This carbonate sand layer is anomalous with respect to the entire Holocene succession known from Green Bay Cave (van Hengstum et al, 2011) or late Holocene successions in nearby Walsingham Cavern (van Hengstum et al, 2015b).…”

Detrital cave sediments record Late Quaternary hydrologic and climatic variability in northwestern Florida, USA

“…Research underwater cave and sinkhole sediment has significantly expanded in the last several decades from the realization that these deposits can preserve records of paleoceanography (Yamamoto et al, 2010;van Hengstum et al, 2015a), tropical cyclone variability (Lane et al, 2011;Brandon et al, 2013;Denomee et al, 2014;van Hengstum et al, 2014), long-term groundwater conditions and salinity (Teeter and Quick, 1990;Teeter, 1995;Alverez Zarikian et al, 2005;Gabriel, 2009;van Hengstum et al, 2010;Quillen et al, 2013), millennial-scale terrestrial-oceanic climatic connectivity (Grimm et al, 1993), glacial-interglacial climate oscillations (Larsen and Mangerud, 1989), vertical sea-level and water-level change (van Hengstum et al, 2011;Collins et al, 2015a), and precipitation variability (Wurster et al, 2008;Polk et al, 2013;Onac et al, 2015). However, many questions still surround their millennial scale sedimentary processes because few flooded caves have received detailed sedimentary reconstructions.…”

“…In vadose caves, allochthonous sediments can be delivered through fluvial, aeolian, or biologic vectors (Ford and Williams, 1989;Bosch and White, 2007;White, 2007), whereas weathering products from regional geologic formations, inorganic internal cave geochemical precipitates, or products of biomineralization often provides autochthonous sediment (Onac et al, 1997;Bosch and White, 2007;White, 2007;Fornós et al, 2009;Onac et al, 2014). As research has expanded into phreatic caves, however, it has become apparent that relating sedimentary facies to specific environmental processes is important for accurate paleo environmental reconstructions.. For example, carbonate mud deposition occurs in coastal submarine caves that are circulated with the ocean (Yamamoto et al, 2010;van Hengstum et al, 2011;van Hengstum et al, 2015a), or calcite rafts precipitation only at modern and paleo-water tables (van Hengstum et al, 2011;Collins et al, 2015a).…”