Research ArticleCLIMATOLOGY

The role of Northeast Pacific meltwater events in deglacial climate change

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Science Advances  26 Feb 2020:
Vol. 6, no. 9, eaay2915
DOI: 10.1126/sciadv.aay2915
  • Fig. 1 Modeled flood from the Columbia River in the glacial simulation, along with the locations of paleoclimate datasets shown/referenced in this study.

    SSS anomaly relative to the control is shown after 1 year. Marine sediment cores include EW0408-85JC, EW0408-87JC, EW0408-66JC, EW0408-26JC, ODP 887, and SO2020-27-6 from the GOA; JT96-09PC and MD02-2496 from the Vancouver margin; and ODP 1019 and W8709-13PC from the California margin, along with locations of the speleothem records from the Oregon Cave National Monument and the Cave of Bells.

  • Fig. 2 Modeled trajectory of a flood from the Columbia River in the glacial and deglacial simulations, with a closed and open Bering Strait, respectively.

    SSS anomalies are shown for model years 5 and 10 for each case, along with the SST anomalies at year 5 for the closed Bering Strait simulation and year 15 for the open Bering Strait simulation. The Kuroshio Current cools in the closed Bering Strait simulation, whereas the Gulf Stream and subpolar North Atlantic cool in response to freshwater migration to this region in the open Bering Strait simulation.

  • Fig. 3 Records of Northeast Pacific alkenone-derived Uk′37 SST reconstructions compared with Greenland ice core records and speleothem records from the western United States spanning the deglaciation and Holocene (left) along with a synthesis of Northeast Pacific paleosalinity records (right).

    (Left) Records from top to bottom: δ18O records from NEEM [dark green; (46)] and NGRIP [light green; (53)] ice cores; Uk′37 records from EW0408-85JC [dark blue; (33)], EW0408-87JC (teal; this paper), EW0408-66JC [light purple; (36)] and EW0408-26JC [purple; (36)], JT96-09PC [magenta; (34)], MD02-2496 [pink; (38)], and ODP 1019 [blue; (35, 37)]; an average of the Northeast (NE) Pacific SST records for the margin sites with a 400-year running average (black); error bars are SEM; speleothem δ18O records from the Oregon Caves National Monument [bright pink; (69, 70)] and Cave of Bells [maroon; (71)]. (Right) δ18Osw-ivc records from EW0408-85JC [dark blue; (33)], EW0408-87JC (teal; this paper), EW0408-66JC [light purple; (36)], EW0408-26JC [purple; (36)], JT96-09PC (magenta; this paper), MD02-2496 [pink; (38)], and ODP 1019 (blue; this paper); an average (standardized, 400-year running average) of the δ18Osw-ivc records for the margin sites (errors bars are SEM), with blue shading denoting negative anomalies (low relative salinity) and maroon shading denoting positive anomalies (higher relative salinity); a reconstruction of surface salinity based on freshwater diatom assemblages from core W8709-13PC [black; (21)] and modeled freshwater discharge into the Pacific [100-year mean, 13P ensemble, dark green; (18)]. Reconstructions of the δ18Osw-ivc are based on paired SST and planktic G. bulloides δ18O records, with the exception of ODP site 1019, which is calculated on the basis of the thermocline-dwelling Nps δ18O record. Direct sample pairs were rare between datasets (plotted as data points), so continuous time series were calculated on the basis of 100-year interpolated records of SST and δ18O and then corrected for the δ18O of changes in global ice volume.

  • Fig. 4 Compilation of Northeastern Pacific surface hydrography and subsurface ventilation records from the LGM to early Holocene in the context of major deglacial climate fluctuations.

    Records from top to bottom: NEEM ice core δ18O record (46) (A), the ODP 1019 SST record (35, 68) (B), the average Northeast Pacific SST record shown in Fig. 3 (C), the NGRIP ice core δ18O record (53) (D), the average Northeast Pacific δ18Osw-ivc record shown in Fig. 3 (E), and the x-ray fluorescence (XRF) Ca/Sr ratio in core U1308 in the North Atlantic inferred to reflect Heinrich events (45) (F). The shaded depth-time plot shows records of B-P radiocarbon age differences from marine sediment cores spanning 680- to 3680-m water depth in the Northeast Pacific (G). Data from shallow to deep: EW0408-85JC (680 m) (40), JT96-09PC (920 m) (41), ODP 1019 (980 m) (42, 43), EW0408-26JC/TC (1620 m), W8709-13PC (2,710 m) (42, 43), ODP 887 (3650 m) (65), and EW0408-87JC (3680 m). Blue bars denote periods of cooling, freshening, and increased B-P age in the North Pacific; the younger event is approximately coeval with the YD.

  • Fig. 5 Global SST anomalies for various deglacial climate intervals.

    Climate intervals shown are early HS1 relative to the LGM (A and B), late HS1 relative to early HS1 (C and D), the BA relative to early HS1 (E and F), the YD relative to the BA (G and H), and the early Holocene relative to the YD (I and J) (see Materials and Methods for data references and dates of climate intervals). SST anomalies for each core site are plotted on the left panels, and an interpolated version using a weighted average grid scheme is shown in the right panels. Maps were generated using Ocean Data View (82).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/9/eaay2915/DC1

    Fig. S1. Modeled SSS, sea-ice, and SST anomalies in the deglacial simulation with an open Bering Strait for model years 5, 10, and 15.

    Fig. S2. Planktic δ18O records from the Northeast Pacific.

    Fig. S3. Compilation of Northeastern Pacific B-P radiocarbon age differences from the LGM through the early Holocene.

    Fig. S4. Compilation of Northeastern Pacific subsurface ventilation records from the LGM through the early Holocene [with ∆14C (‰)] instead of B-P age differences.

    Fig. S5. SST measurements for ODP cores 1019C and 1019A on the original mean core depth splice (red, 1019C; green, 1019A) show misalignment near the Holocene transition by ~30 cm and the BA and YD transitions by ~5 cm.

    Fig. S6. Compilation of Northeast Pacific Uk′37 SST reconstructions on age models with constant marine reservoir correction, in comparison with annual layer counted chronologies of the Greenland ice cores (46, 53) and the absolute U-Th chronologies of the western U.S speleothem records (6971).

    Table S1. A revised mean composite depth for the upper 8 m of ODP core 1019A based on a revised correlation of GRA and MS data to the other cores within the splice for the upper 7 m.

    Table S2. Proxy data used for the global SST anomaly maps in Fig. 5 [(38, 45, 83165) listed in alphabetic order].

    Data file S1. Northeast Pacific SST data.

    Data file S2. Northeast Pacific oxygen isotope data.

    Data file S3. Northeast Pacific radiocarbon data.

    Data file S4. Metadata for global SST compilation.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Modeled SSS, sea-ice, and SST anomalies in the deglacial simulation with an open Bering Strait for model years 5, 10, and 15.
    • Fig. S2. Planktic δ18O records from the Northeast Pacific.
    • Fig. S3. Compilation of Northeastern Pacific B-P radiocarbon age differences from the LGM through the early Holocene.
    • Fig. S4. Compilation of Northeastern Pacific subsurface ventilation records from the LGM through the early Holocene with ∆14C (‰) instead of B-P age differences.
    • Fig. S5. SST measurements for ODP cores 1019C and 1019A on the original mean core depth splice (red, 1019C; green, 1019A) show misalignment near the Holocene transition by ~30 cm and the BA and YD transitions by ~5 cm.
    • Fig. S6. Compilation of Northeast Pacific Uk′37 SST reconstructions on age models with constant marine reservoir correction, in comparison with annual layer counted chronologies of the Greenland ice cores (46, 53) and the absolute U-Th chronologies of the western U.S speleothem records (6971).
    • Table S1. A revised mean composite depth for the upper 8 m of ODP core 1019A based on a revised correlation of GRA and MS data to the other cores within the splice for the upper 7 m.
    • Table S2. Proxy data used for the global SST anomaly maps in Fig. 5 (38, 45, 83165) listed in alphabetic order.

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    Other Supplementary Material for this manuscript includes the following:

    • Data file S1 (Microsoft Excel format). Northeast Pacific SST data.
    • Data file S2 (Microsoft Excel format). Northeast Pacific oxygen isotope data.
    • Data file S3 (Microsoft Excel format). Northeast Pacific radiocarbon data.
    • Data file S4 (Microsoft Excel format). Metadata for global SST compilation.

    Files in this Data Supplement:

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