Research ArticleCLIMATOLOGY

The tropical lapse rate steepened during the Last Glacial Maximum

See allHide authors and affiliations

Science Advances  27 Jan 2017:
Vol. 3, no. 1, e1600815
DOI: 10.1126/sciadv.1600815
  • Fig. 1 Topographic map of eastern Africa.

    The locations of Lake Rutundu, Mount Kenya (0°03′S, 37°28′E), Sacred Lake, Mount Kenya (0°03′N, 37°32′E), Lake Tanganyika (6°42′S, 29°50′E), Lake Malawi (10°16′S, 34°19′E), and the Rwenzori Mountains (0°23′N, 29°52′E) are indicated with circles.

  • Fig. 2 Reconstructed time series of temperature change from the LGM to the present along an elevational gradient in tropical East Africa.

    (A) Lake Rutundu (data from this study, with two outliers removed). (B) Sacred Lake (20). (C) Lake Tanganyika (19). (D) Lake Malawi (18). Shading on the reconstructions denotes 68 and 95% confidence intervals (CIs) based on bootstrapping of the respective calibrations. Gray vertical shading denotes the age range of the regional LGM, defined by 10Be ages of moraines from the Rwenzori Mountains, Uganda (22), the YD, and the PI reference interval used to calculate the lapse rate. The moraine ages are plotted in white boxes with 1σ error bars.

  • Fig. 3 Reconstructed changes in lapse rate (Γ) and FLH since the LGM.

    (A) Temperature versus elevation for the four lake sites (1820) and the western equatorial Indian Ocean (24, 25) are plotted as blue circles, and the accompanying linear regression with the 68% CI is shown as the blue line with shading (see the Supplementary Materials). The modern temperature regression and 68% CI (see the Supplementary Materials) are plotted in red for reference. (B) Probability distribution plots of LGM to modern elevation changes for the FLH based on GDGT temperature reconstructions (blue) and East African ELAs (27).

  • Fig. 4 Comparison of East African paleotemperature data with CMIP5/PMIP3 model output.

    (A) Site-specific temperature change (ΔT) and (B) lapse-rate change (ΔΓLGM) between the LGM and PI. Red filled circles show temperature changes from GDGT proxy records, and black dots and lines mark the 1σ errors of these changes. Box and whisker plots show results from the CMIP5/PMIP3 models.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/1/e1600815/DC1

    fig. S1. Lake Rutundu brGDGT-based temperature reconstruction with 68 and 95% CIs and 14C age control points.

    fig. S2. Age models for the Lake Rutundu cores with data supporting stratigraphic correlations between the cores.

    fig. S3. Age models for cores from Sacred Lake, Lake Tanganyika, and Lake Malawi.

    fig. S4. brGDGT and TEX86 temperature calibrations.

    fig. S5. Modern elevation versus temperature data over East Africa derived from NCEP reanalysis data and temperature loggers in the Rwenzori Mountains.

    fig. S6. Map showing geographic variations in the temperature lapse rate over East Africa derived from NCEP reanalysis data.

    fig. S7. Correlations between changes in the lapse rate and humidity and mean tropical temperature as simulated by the CMIP5/PMIP3 models.

    table S1. brGDGT temperature reconstructions from Lake Rutundu.

    table S2. Radiocarbon ages used to construct an age model for the Lake Rutundu core.

    table S3. 210Pb data used to construct an age model for the Lake Rutundu core.

    table S4. Temperatures, lapse rates, and ECSs of the CMIP5/PMIP3 climate models used in this study.

    table S5. Summary information about the CMIP5/PMIP3 models used in this study.

    References (5259)

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Lake Rutundu brGDGT-based temperature reconstruction with 68 and 95% CIs and 14C age control points.
    • fig. S2. Age models for the Lake Rutundu cores with data supporting stratigraphic correlations between the cores.
    • fig. S3. Age models for cores from Sacred Lake, Lake Tanganyika, and Lake Malawi.
    • fig. S4. brGDGT and TEX86 temperature calibrations.
    • fig. S5. Modern elevation versus temperature data over East Africa derived from NCEP reanalysis data and temperature loggers in the Rwenzori Mountains.
    • fig. S6. Map showing geographic variations in the temperature lapse rate over East Africa derived from NCEP reanalysis data.
    • fig. S7. Correlations between changes in the lapse rate and humidity and mean tropical temperature as simulated by the CMIP5/PMIP3 models.
    • table S1. brGDGT temperature reconstructions from Lake Rutundu.
    • table S2. Radiocarbon ages used to construct an age model for the Lake Rutundu core.
    • table S3. 210Pb data used to construct an age model for the Lake Rutundu core.
    • table S4. Temperatures, lapse rates, and ECSs of the CMIP5/PMIP3 climate models used in this study.
    • table S5. Summary information about the CMIP5/PMIP3 models used in this study.
    • References (52–59)

    Download PDF

    Files in this Data Supplement:

Navigate This Article