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A Reconstruction of Regional and Global Temperature for the Past 11,300 Years

Science  08 Mar 2013:
Vol. 339, Issue 6124, pp. 1198-1201
DOI: 10.1126/science.1228026

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  1. Fig. 1

    Comparison of different methods and reconstructions of global and hemispheric temperature anomalies. (A and B) Globally stacked temperature anomalies for the 5° × 5° area-weighted mean calculation (purple line) with its 1σ uncertainty (blue band) and Mann et al.'s global CRU-EIV composite mean temperature (dark gray line) with their uncertainty (light gray band). (C and D) Global temperature anomalies stacked using several methods (Standard and Standard5x5Grid; 30x30Grid; 10-lat: Arithmetic mean calculation, area-weighted with a 5° × 5° grid, area-weighted with a 30° × 30° grid, and area-weighted using 10° latitude bins, respectively; RegEM and RegEM5x5Grid: Regularized expectation maximization algorithm-infilled arithmetic mean and 5° × 5° area-weighted). The gray shading [50% Jackknife (Jack50)] represents the 1σ envelope when randomly leaving 50% of the records out during each Monte Carlo mean calculation. Uncertainties shown are 1σ for each of the methods. (E and F) Published temperature anomaly reconstructions that have been smoothed with a 100-year centered running mean, Mann08Global (2), Mann08NH (2), Moberg05 (3), WA07 (8), Huange04 (36), and plotted with our global temperature stacks [blue band as in (A)]. The temperature anomalies for all the records are referenced to the 1961–1990 instrumental mean. (G and H) Number of records used to construct the Holocene global temperature stack through time (orange line) and Mann et al.'s (2) reconstruction (gold vertical bars). Note the y axis break at 100. The latitudinal distribution of Holocene records (gray horizontal bars) through time is shown. (I and J) Number of age control points (e.g., 14C dates) that constrain the time series through time.

  2. Fig. 2

    Holocene climate forcings and paleoclimate records. Contour plots of (A) December, (B) June, and (C) annual mean latitudinal insolation anomalies relative to present for the past 11,500 years (36). (D) Calculated radiative forcing (28) derived from ice-core greenhouse gases (GHG) (CO2 + N2O + CH4). (E) Total solar irradiance anomalies (ΔTSI) relative to 1944–1988 CE derived from cosmogenic isotopes (31). (F and G) Proxies for the strength of the Atlantic meridional overturning circulation (37, 38). (H) Volcanic sulfate flux (in kg/km2) from Antarctica (32) and volcanic sulfate concentration (in parts per billion) from Greenland (33) in 100-year bins. Both records are normalized relative to the volcanic sulfate flux/concentration associated with the Krakatoa eruption. (I to K) Zonal mean temperature reconstructions for 60° latitude bands from this study compared to speleothem (14, 15, 1720) and Ti data (16), which are proxies for precipitation and local temperature. Speleothem data sets were smoothed with a seven-point running mean for clarity. ITCZ, Intertropical Convergence Zone; EASM, East Asian Summer Monsoon; AISM, Australian-Indonesian Summer Monsoon.

  3. Fig. 3

    Holocene temperature distribution compared to modern temperature and future projections. Shown are relative frequency plots of Holocene temperature anomalies in 0.05°C bins using multiple data subsets and reconstructions (colored lines), instrumental means for 1900–1909 and 2000–2009 CE (vertical black lines), 2100 CE projections based on various emissions scenarios (35) (black squares and gray bars give the best estimate and 66% confidence interval), and the Holocene median and 66% range from Standard5×5 + high-frequency stack (black square and blue bar). Projections in (35) were referenced to 1980–1999 CE, whereas we reference them to 1961–1990 CE here. Data sets are divided by proxy type: UK'37, Mg/Ca, and the remainder (Other); method: arithmetic mean (Standard) and RegEM; weighting: equal Northern and Southern Hemisphere weighting (0.5NH + 0.5SH), 5° × 5°grid, and 30° × 30°grid; exclusion of data sets: no North Atlantic and Jack50; and high-frequency addition: red noise with the same power spectrum as Mann et al. (2) added to the global stack (supplementary materials).

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