New estimates of the magnitude of the sea-level jump during the 8.2 ka event

Obrist‐Farner, Jonathan; Brenner, Mark; Stone, Jeffery R.; Wojewódka-Przybył, Marta; Bauersachs, Thorsten; Eckert, Andreas; Locmelis, Marek; Curtis, Jason H.; Zimmerman, Susan; Correa‐Metrio, Alex; Schwark, Lorenz; Duarte, Edward; Schwalb, Antje; Niewerth, Etienne; Echeverría‐Galindo, Paula; Pérez, Liseth

doi:10.1130/g49296.1

Cited by 11 publications

(3 citation statements)

References 34 publications

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“…We infer that positive PC1 scores indicate an increase in catchment erosion and runoff (e.g., Davies et al., 2015; Duarte et al., 2021; Kylander et al., 2011; Figure 4), similar to the observations in the Petén core. Principal component 2 (12.9% of variance) for the LI core, however, mostly reflects changes in Sr and S. The processes that PC2 scores and the Ca and Ti ratio (Figure S7 in Supporting Information ) reflect at Lake Izabal are ambiguous because S, Sr, and Ca in the lake can be related to evaporation, marine water transgression, or redox processes (Duarte et al., 2021; Obrist‐Farner et al., 2022), and therefore are not used as indicators of hydroclimate in Izabal.…”

Section: Results and Interpretationsmentioning

confidence: 99%

Incoherency in Central American Hydroclimate Proxy Records Spanning the Last Millennium

Obrist‐Farner

Steinman

Stansell

et al. 2023

Paleoceanog and Paleoclimatol

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Continued global warming is expected to result in reduced precipitation and a drier climate in Central America. Projections of future changes are highly uncertain, however, due to the spatial resolution limitations of models and insufficient observational data coverage across space and time. Paleoclimate proxy data are therefore critical for understanding regional climate responses during times of global climate reorganization. Here we present two lake‐sediment based records of precipitation variability in Guatemala along with a synthesis of Central American hydroclimate records spanning the last millennium (800–2000 CE). The synthesis reveals that regional climate changes have been strikingly heterogeneous, even over relatively short distances. Our analysis further suggests that shifts in the mean position of the Intertropical Convergence Zone, which have been invoked by numerous studies to explain variability in Central American and circum‐Caribbean proxy records, cannot alone explain the observed pattern of hydroclimate variability. Instead, interactions between several ocean‐atmosphere processes and their disparate influences across variable topography appear to have resulted in complex precipitation responses. These complexities highlight the difficulty of reconstructing past precipitation changes across Central America and point to the need for additional paleo‐record development and analysis before the relationships between external forcing and hydroclimate change can be robustly determined. Such efforts should help anchor model‐based predictions of future responses to continued global warming.

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Section: Results and Interpretationsmentioning

confidence: 99%

Incoherency in Central American Hydroclimate Proxy Records Spanning the Last Millennium

Obrist‐Farner

Steinman

Stansell

et al. 2023

Paleoceanog and Paleoclimatol

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“…In the absence of micropaleontological fossils and sedimentary structures, authigenic minerals and geochemistry may provide useful insights. Previous studies have shown that the content of pyrite sulfur and the ratio of total sulfur to total organic carbon (TS/TOC, hereby written as C/S) can indicate sea-level changes (Hepp et al, 2019;Liu et al, 2020;Liu X. T., et al, 2021;Liu X. T., et al, 2021;Obrist-Farner et al, 2021;Chang et al, 2023). Typical marine sediments are characterized by an average C/S of 2.8 ± 1.5 (Berner, 1984;Raiswell and Canfield, 2012), and this ratio has been successfully applied to tracing environmental evolution of continental shelves and estuaries since the last deglaciation (Liu X. T., et al, 2018;Liu et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Geochemical behavior of C, N, and S in sediments of Hangzhou Bay, Southeastern China: implications for the study of paleoclimate and sea-level changes

Gao,

Piotrowski,

et al. 2024

Front. Mar. Sci.

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The correlation between the amount of organic carbon (OC) and sulfur (S) in sediments has been widely used as a paleosalinity indicator to distinguish between marine and freshwater environments. However, whether the ratio of total OC to total S (TOC/TS) can be used to identify unsteady or dynamic marine environments across sedimentary strata is still contended. An HZW1907 sediment core of 80 m in length was successfully collected in the middle of Hangzhou Bay (HZB), serving as one of the few boreholes that are crucial for the study of geologic and geo-environment changes in the coastal regions of eastern China since the Last Glacial Maximum (LGM). Total OC (TOC), stable carbon isotope, and TS of 82 subsamples from the HZW1907 core were analyzed to reconstruct the history of the shallow water biological pump and sulfur preservation record in the bay since the Late Pleistocene. Our results indicate that the samples had low concentrations of TOC (0.21%) and total nitrogen (TN) (0.02%), high mass ratio of TOC/TN (10.8), low δ13C (−24.9‰), low TS content (0.06%), and a high ratio of TOC/TS (9.1) from 33.6 ka BP to 12.3 ka BP, implying that freshwater organic matter (OM), algae, and C3 plant fragments were the main sources of OM in a relatively cold environment. The abundances of TOC, TN, and TS increased to 0.56%, 0.07%, and 0.4%, respectively, while δ13C (−23.9‰) increased and TOC/TS (2.7) decreased in the Holocene sediments, suggesting that seawater began to influence the composition of the sediments of HZB. Climate warming, which is likely to have impacted the results, was experienced from 12.3 ka BP. An OC isotope mixing model indicated that since the Mid-late Holocene, more than 70% of riverine OM accounted for the total OM. The TOC/TS ratio was identified as an effective indicator of seawater intrusion, with C/S ratios of 1–6 being considered to indicate a “sea–land transitional zone” sedimentary environment, a C/S >6 indicating freshwater, and a C/S<1 indicating normal marine facies. These findings provide crucial evidence for using TOC/TS to distinguish freshwater from marine environments and enhance our understanding of past climate changes. Therefore, these geochemical indicators can be used in conjunction with other sedimentary records to obtain accurate results about sedimentary evolution.

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“…Lake Izabal is the largest lake in Guatemala, and is fed by a large and complex network of rivers (Obrist‐Farner et al., 2020). Lake Izabal also contains a deep sedimentary record that spans millions of years, and could be a valuable repository of paleoclimate data (Bartole et al., 2019; Duarte et al., 2021; Obrist‐Farner et al., 2022, 2023), including reconstructions based on leaf wax isotope data. We sampled sediments from across the LIB, including three major rivers that feed the lake, as well as the lake itself and marshes adjacent to the Polochic river delta.…”

Section: Introductionmentioning

confidence: 99%

Distinct Modes of Aged Soil Carbon Export in a Large Tropical Lake Basin Identified Using Bulk and Compound‐Specific Radiocarbon Analyses of Fluvial and Lacustrine Sediment

Parker¹,

Ahad

Obrist‐Farner

et al. 2023

JGR Biogeosciences

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The 14C content of sedimentary organic matter and specific organic molecules provide valuable information on the source and age of organic matter stored in sediments, but these data are limited for tropical fluvial and lake sediments. We analyzed 14C in bulk organic matter, palmitic acid (C16), and long‐chain n‐alkanoic acids (C24, C26, C28), within fluvial and lake sediments in the catchment of Lake Izabal, a large tectonic lake basin in Guatemala. We combined these measurements with bulk and compound‐specific δ13C measurements, as well as sediment OC:N ratios, to understand the source and age of sedimentary organic matter in different regions of the lake catchment. Most fatty acid and bulk OM samples were characterized by pre‐modern carbon, indicating important input of aged carbon with residence times of hundreds to thousands of years into sediments. We identified two mechanisms leading to aged carbon export to sediments. In the high‐relief and deforested Polochic catchment, older OM and fatty acids are associated with low %TOC and low OC:N, indicating aged organic matter associated with eroded mineral soil. In the smaller, low‐relief, and largely forested Oscuro catchment, old OM and fatty acids are associated with high %TOC and high OC:N ratios, indicating export of undegraded aged plant biomass from swamp peat. The age of bulk OM and fatty acids in Lake Izabal sediments is similar to the ages observed in fluvial sediments, implying that fluvial input of aged soil carbon makes an important contribution to lake sediment carbon reservoirs in this large tropical lake.

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New estimates of the magnitude of the sea-level jump during the 8.2 ka event

Cited by 11 publications

References 34 publications

Incoherency in Central American Hydroclimate Proxy Records Spanning the Last Millennium

Incoherency in Central American Hydroclimate Proxy Records Spanning the Last Millennium

Geochemical behavior of C, N, and S in sediments of Hangzhou Bay, Southeastern China: implications for the study of paleoclimate and sea-level changes

Distinct Modes of Aged Soil Carbon Export in a Large Tropical Lake Basin Identified Using Bulk and Compound‐Specific Radiocarbon Analyses of Fluvial and Lacustrine Sediment

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