Climate response to the 8.2 ka event in coastal California

Abstract

A fast-growing stalagmite from the central California coast provides a high-resolution record of climatic changes synchronous with global perturbations resulting from the catastrophic drainage of proglacial Lake Agassiz at ca. 8.2 ka. High frequency, large amplitude variations in carbon isotopes during the 8.2 ka event, coupled with pulsed increases in phosphorus concentrations, indicate more frequent or intense winter storms on the California coast. Decreased magnesium-calcium ratios point toward a sustained increase in effective moisture during the event, however the magnitude of change in Mg/Ca suggests this event was not as pronounced on the western North American coast as anomalies seen in the high northern latitudes and monsoon-influenced areas. Nevertheless, shifts in the White Moon Cave record that are synchronous within age uncertainties with cooling of Greenland, and changes in global monsoon systems, suggest rapid changes in atmospheric circulation occurred in response to freshwater input and associated cooling in the North Atlantic region. Our record is consistent with intensification of the Pacific winter storm track in response to North Atlantic freshwater forcing, a mechanism suggested by simulations of the last deglaciation, and indicates this intensification led to increases in precipitation and infiltration along the California coast during the Holocene.

Evaluating model outputs using integrated global speleothem records of climate change since the last glacial

“…6a; Cruz et al, 2005) but no clear changes in the relative error terms for SSC01 (Gunung-buda cave; Fig. 6b; Partin et al, 2007). These results suggest that, with an LGM window width of ±1000 years, the relative contribution of age uncertainty to the anomaly uncertainty is small (Fig.…”

“…This precludes a general assessment of the impact of temporal uncertainties on data-model comparisons. Nevertheless, we assess these impacts for the LGM for two records (entity BT-2 from Botuverá cave: Cruz et al, 2005; and entity SSC01 from Gunung-buda cave: Partin et al, 2007) for which new age-depth models have been prepared using COPRA (Breitenbach et al, 2012). We created 1000-member ensembles of the age-depth relationship using the original author's choice of radiometric dates and pchip (piecewise cubic hermite interpolating polynomial) interpolation.…”

Subdividing the Holocene Series/Epoch: formalization of stages/ages and subseries/subepochs, and designation of GSSPs and auxiliary stratotypes

“…This cooling occurs at~8.2 ka in the NGRIP1 core (where it marks the GSSP) and corresponds to the "8.2-ka climatic event," a short-lived near-global episode that is reflected in a wide range of proxy climate records (e.g. Allan et al, 2018;Chase et al, 2015a;Cheng et al, 2009;Daley et al, 2011;Morrill et al, 2013;Oster et al, 2017;Roffet-Salque et al, 2018;Rohling and Pälike, 2005;Siani et al, 2013;Sicre et al, 2013). In the Greenland NGRIP1 ice core, the event is located at a depth of 1228.67 m (Fig.…”

Speleothem Paleoclimatology for the Caribbean, Central America, and North America

“…This regional variability in the climatic controls on δ 18 Op influences the dominant controls on δ 18 Ospel and as such different aspects of climate variability can be recovered in different locations. Speleothem oxygen isotope records that are most proximal to the Pacific coast are interpreted to respond to changes in surface air temperature that influence δ 18 Op [42] with some influence by changes in moisture source between more North Pacific and subtropical AR sources [43][44][45]. A modern (last ~1200 years) record of δ 18 Ospel from the southern Sierra Nevada mountains that is not included in SISAL_v1 is interpreted to reflect changes in moisture source that are ultimately driven by northwestern Pacific sea surface temperature changes that influence storm track trajectories [46].…”

“…The OCNM02-01 record on the other hand, has been tied to changes in northeast Pacific sea surface temperature and winter insolation [42]. The 8.2 ka event is recorded in a high-resolution coastal California speleothem that is not included in SISAL_v1 [44] as a period of enhanced winter storminess. However, further inland LC-1 shows the highest δ 18 O spel at this time and no evidence of an 8.2 ka cold event [3,47].…”