Browsing by Author "Jaccard, SL"

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    Export production in the New-Zealand region since the last glacial maximum
    (Elsevier B. V., 2017-07-01) Durand, A; Chase, Z; Noble, TL; Bostock, HC; Jaccard, SL; Kitchener, P; Townsend, AT; Jansen, N; Kinsley, L; Jacobsen, GE; Johnson, S; Neil, H
    Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand. For the first time in this region, 230-Thorium-normalised fluxes of biogenic opal, carbonate, excess barium, and organic carbon are presented. In Subtropical Waters and the SAZ, these flux variations show that EP has not changed markedly since the LGM. The only exception is a site currently north of the subtropical front. Here we suggest the subtropical front shifted over the core site between 18 and 12 ka, driving increased EP. To understand why EP remained mostly low and constant elsewhere, lithogenic fluxes at the four sites were measured to investigate changes in dust deposition. At all sites, lithogenic fluxes were greater during the LGM compared to the Holocene. The positive temporal correlation between the Antarctic dust record and lithogenic flux at a site in the Tasman Sea shows that regionally, increased dust deposition contributed to the high glacial lithogenic fluxes. Additionally, it is inferred that lithogenic material from erosion and glacier melting deposited on the Campbell Plateau during the deglaciation (18–12 ka). From these observations, it is proposed that even though increased glacial dust deposition may have relieved iron limitation within the SAZ around New Zealand, the availability of silicic acid limited diatom growth and thus any resultant increase in carbon export during the LGM. Therefore, silicic acid concentrations have remained low since the LGM. This result suggests that both silicic acid and iron co-limit EP in the SAZ around New Zealand, consistent with modern process studies. © 2017 Elsevier B.V.
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    A global database of holocene paleotemperature records
    (Springer Nature Limited, 2020-04-14) Kaufman, DS; McKay, N; Rouston, C; Erb, M; Davis, B; Heiri, O; Jaccard, SL; Tierney, J; Dätwyler, C; Axford, Y; Brussel, T; Cartapanis, O; Chase, BM; Dawson, A; de Vernal, A; Engels, S; Jonkers, L; Marsicek, J; Moffa-Sánchez, P; Morrill, C; Oris, A; Rehfeld, K; Saunders, KM; Sommer, PS; Thomas, E; Tonello, M; Tóth, M; Vachula, R; Andreev, A; Bertrand, S; Biskaborn, B; Bringué, M; Brooks, S; Caniupán, M; Chevalier, M; Cwynar, L; Emile-Geay, J; Fegyveresi, J; Feurdean, A; Finsinger, W; Fortin, MC; Foster, L; Fox, M; Gajewski, K; Grosjean, M; Hausmann, S; Heinrichs, M; Holmes, N; Ilyashuk, B; Ilyashuk, E; Juggins, S; Khider, D; Koinig, K; Langdon, P; Larocque-Tobler, I; Li, JY; Lotter, A; Luoto, T; Mackay, A; Magyari, E; Malevich, S; Mark, B; Massaferro, J; Montade, V; Nazarova, L; Novenko, E; Pařil, P; Pearson, E; Peros, M; Peinitz, R; Płóciennik, M; Porinchu, D; Potito, A; Rees, ABH; Reinemann, S; Roberts, SJ; Rolland, N; Salonen, S; Self, A; Seppä, H; Shala, S; St-Jacques, JM; Stenni, B; Syrykh, L; Tarrats, P; Taylor, K; van den Bos, V; Velle, G; Wahl, E; Walker, I; Wilmshurst, J; Zhang, E; Zhilich, S
    A comprehensive database of paleoclimate records is needed to place recent warming into the longer-term context of natural climate variability. We present a global compilation of quality-controlled, published, temperature-sensitive proxy records extending back 12,000 years through the Holocene. Data were compiled from 679 sites where time series cover at least 4000 years, are resolved at sub-millennial scale (median spacing of 400 years or finer) and have at least one age control point every 3000 years, with cut-off values slackened in data-sparse regions. The data derive from lake sediment (51%), marine sediment (31%), peat (11%), glacier ice (3%), and other natural archives. The database contains 1319 records, including 157 from the Southern Hemisphere. The multi-proxy database comprises paleotemperature time series based on ecological assemblages, as well as biophysical and geochemical indicators that reflect mean annual or seasonal temperatures, as encoded in the database. This database can be used to reconstruct the spatiotemporal evolution of Holocene temperature at global to regional scales, and is publicly available in Linked Paleo Data (LiPD) format. © 2020 The Authors