Browsing by Author "McKay, N"

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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
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    Salinity information from hydro-sensitive, biogenic marine carbonate δ18O records
    (American Geophysical Union (AGU), 2021-12-14) Thompson, DM; Conroy, JL; Williams, B; Konecky, BL; Stevenson, S; DeLong, KL; McKay, N; Dassie, EP; Fischer, MJ; Jonkers, L; Martrat, B; Pages ISO2K Project Members
    Stable oxygen isotope ratios in marine biogenic carbonates (δ18Ocarb, e.g., from corals, coralline algae, bivalves, sclerosponges) have greatly extended the instrumental record, providing invaluable information about climate variability and change from the tropics to high latitudes. These δ18Ocarb records reflect seawater temperature and δ18O (δ18Osw) at the time of calcification, which occurs sufficiently rapidly to permit reconstruction of sub-annual to annual variability over the lifetime of the organism. δ18Osw is strongly related to salinity, as both are similarly impacted by hydroclimate processes such as precipitation, evaporation, and advection. Many studies have leveraged δ18Ocarb and the tendency for temperature and salinity to covary constructively in the tropics (e.g., warm with wet or low salinity, and vice versa) to reconstruct changes in major modes of climate variability and responses to forcings. However, with limited networks of in situ seawater temperature, salinity, and δ18O measurements, quantifying the relative contribution of temperature and δ18Osw to δ18Ocarb variability remains a large source of uncertainty. Here we use ‘pseudo-carbonate’ δ18O records modeled from temperature and salinity to identify sites where salinity contributes substantially to δ18Ocarb variance. These ‘hydro-sensitive’ δ18Ocarb records are located predominantly in the Indo-Pacific Warm Pool, Caribbean Sea, Gulf of Mexico, and Aleutian Archipelago. Notably, we find that temperature and salinity vary destructively in δ18Ocarb (i.e., warm with drier or higher salinity) in many regions for which high-resolution paleoclimate reconstructions have provided key constraints on ocean circulation—the eastern equatorial Pacific, the North Atlantic, and at depth. However, the inferred salinity variability at these sites is sensitive to uncertainties in the δ18Osw-salinity relationship, emphasizing the need for a coordinated network of in situ salinity and δ18Osw measurements. Plain-language Summary Ocean salinity integrates valuable information about changes in the global water cycle, including changes in precipitation, evaporation, and ocean currents. However, our understanding of recent salinity changes are hampered by the limited coverage of direct salinity measurements. Many marine organisms incorporate information about their local environment in their skeleton as they grow, providing indirect evidence of past ocean salinity. The interpretation of these records is dependent on the relative magnitude of temperature and salinity signal recorded, and in turn, how these variables relate to one another. We show that samples from the western Pacific Ocean, eastern Indian Ocean, Caribbean Sea, Gulf of Mexico, and Aleutian Archipelago are most likely to provide reliable salinity information across seasons, years, and decades, as the organisms in these regions primarily record salinity at all timescales. Finally, we show that direct seawater observations are critical to improve the salinity information obtained from the skeletons of marine organisms.