Research ArticlePALEOCLIMATE

State dependence of climatic instability over the past 720,000 years from Antarctic ice cores and climate modeling

See allHide authors and affiliations

Science Advances  08 Feb 2017:
Vol. 3, no. 2, e1600446
DOI: 10.1126/sciadv.1600446
  • Fig. 1 Millennial-scale variability in water isotopes and dust flux records during the past 720,000 years for comparison of Dome Fuji ice-core data with Dome C data.

    (A) δ18O record from DF1 core (pink) (1, 2) and DF2 core (red; this study) (see Materials and Methods). (B) δD record from Dome C core (19) relative to VSMOW (Vienna standard mean ocean water). (C) Dome Fuji dust flux. DF1 for younger part (53) and DF2 for older part (this study). (D) Dome C dust flux (17). (E) Composite isotope record. (F) Low-pass filtered isotope records [cutoff periods, 3 ky (red line) and 18 ky (gray line)] shifted downward by 4 units for visibility. (G) AIMs detected primarily using low-pass filtered isotopic composite (red triangles) and those with additionally detected events, primarily using the Dome C dust record (purple triangles) (see text). (H) First derivative of (F) (solid green line) and threshold for AIM detection (black dotted line). (I) Second derivative of (F) (solid green line) and threshold for AIM detection (black dotted line). For (A), (B), (E), and (F), gray dashed lines indicate means. For (C) and (D), thin dotted lines indicate raw data, and thick lines indicate the 1000-year running average. Note the inverted axis scale for (C) and (D). Age scale for all records is the combination of DFO-2006 for the last three glacial cycles and AICC2012 for the older period (see Materials and Methods). BP, before present.

  • Fig. 2 Water isotope and dust flux records from Dome Fuji and Dome C in the oldest glacial period (MIS 16).

    (A) δD record from Dome C core (19). (B) δ18O record from DF2 core (this study). (C) Dome Fuji dust flux (this study). (D) EDC dust flux (17). Black arrows indicate nine millennial-scale AIMs identified in low-pass filtered isotopic curve (Fig. 1F). Dotted arrows indicate small AIMs visible in the high-resolution data. All records are on the AICC2012 age scale.

  • Fig. 3 Frequency of AIM and its relationship with Antarctic temperature.

    Return time of AIM plotted against the composite Antarctic isotope record filtered on orbital time scales (Fig. 1F) for 0 to 400 ky (blue circles) and 400 to 700 ky (green diamonds). Median values of return time are plotted as horizontal bars. (A) From AIMs detected in 3-ky low-pass filtered isotopic composite with constant thresholds for the first and second derivatives, with validation by dust records. (B) From AIMs detected using Dome C dust record and validation by unsmoothed isotopic records through visual inspection. Return time for abrupt warming in Greenland (on DFO-2006 time scale) is also plotted (red squares). In each panel, the value of zero on horizontal axis indicates the mean of isotopic composite curve, corresponding to −57.13‰ for Dome Fuji δ18O and −421.3‰ for Dome C δD records.

  • Fig. 4 Results of MIROC freshwater hosing simulations (0.05 sverdrup) for temperature and precipitation.

    (A) Map of atmospheric temperature difference and (B) precipitation difference between hosing and control experiments for interglacial climate (mean for 400 to 500 model years after onset of hosing, which is the last 100 years of the “hosing” period). As in (A) and (B), but for (C and D) midglacial climate and (E and F) full-glacial climate. As in (A) and (B), but for sensitivity experiment of (G and H) midglacial climate “without” ice sheet and for (I and J) interglacial climate “with” ice sheet. In the left panels, solid line (dashed line) contours are drawn for every degree Celsius of temperature increase (decrease). The right panels show the same climatological pattern (preindustrial, contour lines) and anomaly in % (colors) caused by freshwater hosing (mean for 400 to 500 model years) for each climate state.

  • Fig. 5 Time evolution results of the MIROC climate model simulation with freshwater hosing.

    (A) Top to bottom: Time series of maximum AMOC strength, North Atlantic sea ice extent (February sea ice of 90% concentration), and atmospheric temperature (2 m above the surface) at Greenland summit (average from December to February) and Dome Fuji (Antarctica, annual mean) under the midglacial climate after the onset of freshwater hosing of 0.05 sverdrup. The freshwater anomaly is applied for 500 years (shown as blue bar above the time axis) and then switched off, and the integration continues for an additional 700 model years (total simulation run of 1200 years is shown). (B) Maximum AMOC strength of the three experiments for the 500 years after the onset of 0.05-sverdrup hosing (red, interglacial; green, midglacial; blue full-glacial). (C) Maximum AMOC strength as in (B) for the case of 0.1-sverdrup hosing.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/2/e1600446/DC1

    Supplementary Notes

    fig. S1. Location of Dome Fuji, East Antarctica.

    fig. S2. Dome Fuji data on a depth scale.

    fig. S3. Matching of Dome Fuji and Dome C ice-core records.

    fig. S4. Return time of AIM compared with the Red Sea relative sea level.

    fig. S5. Comparison of AIM identification with various smoothings of the isotopic record.

    fig. S6. As in Fig. 3A, but with various smoothings of the isotopic record.

    fig. S7. Data for AIM detection.

    fig. S8. Time evolution results of the MIROC climate model simulation with freshwater hosing.

    fig. S9. Simulation results with the MIROC climate model for surface air temperature change.

    fig. S10. Results of MIROC climate model simulation of wind speed.

    fig. S11. Results of MIROC climate model simulation of AMOC.

    fig. S12. Results of MIROC climate model simulation of sea ice and convection in Northern Hemisphere.

    fig. S13. As in fig. S12, but for the Southern Ocean.

    fig. S14. Bed elevation around the ice coring site at Dome Fuji.

    table S1. Overview of forcings imposed on MIROC AOGCM in the present study.

    table S2. Thresholds for AIM detection.

    References (8285)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Notes
    • fig. S1. Location of Dome Fuji, East Antarctica.
    • fig. S2. Dome Fuji data on a depth scale.
    • fig. S3. Matching of Dome Fuji and Dome C ice-core records.
    • fig. S4. Return time of AIM compared with the Red Sea relative sea level.
    • fig. S5. Comparison of AIM identification with various smoothings of the isotopic record.
    • fig. S6. As in Fig. 3A, but with various smoothings of the isotopic record.
    • fig. S7. Data for AIM detection.
    • fig. S8. Time evolution results of the MIROC climate model simulation with freshwater hosing.
    • fig. S9. Simulation results with the MIROC climate model for surface air temperature change.
    • fig. S10. Results of MIROC climate model simulation of wind speed.
    • fig. S11. Results of MIROC climate model simulation of AMOC.
    • fig. S12. Results of MIROC climate model simulation of sea ice and convection in Northern Hemisphere.
    • fig. S13. As in fig. S12, but for the Southern Ocean.
    • fig. S14. Bed elevation around the ice coring site at Dome Fuji.
    • table S1. Overview of forcings imposed on MIROC AOGCM in the present study.
    • table S2. Thresholds for AIM detection.
    • References (82–85)

    Download PDF

    Files in this Data Supplement:

Navigate This Article