A 3000-year high-resolution stalagmitebased record of palaeoclimate for northeastern South Africa

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Abstract
High-resolution stable isotope variations and growth structure analyses of the last three millennia of a 6600-year stalagmite record at Cold Air Cave, Makapansgat Valley, South Africa, are presented. Growth layers, which are measurable over the last 250 years, are shown to be annual. The correlation between the width of growth layers and precipitation is strongly positive. Changes inδ18O andδ13C are positively correlated and inversely correlated to changes in the colour of the growth layers in the stalagmite. Variations in colour are directly correlated with mean annual temperature. Dark colouration is the product of increased temperature and mobilization of organic matter from the soil, and is associated with wetter summers and enhanced growth of C4 grasses. Darker colouring and enrichedδ18O andδ13C reflect a warmer, wetter environment, whereas lighter colouring and depleted isotopic values are indicative of cooler, drier conditions. The dominant episode in the 3000-year record is the cool, dry 500-year manifestation of the‘Little Ice Age’, from ad 1300 to about 1800, with the lowest temperatures at around ad 1700. The four centuries from ad 900 to 1300, experiencing above-average warming and high variability, may be the regional expression of the medieval warming. Other cool, dry spells prevailed from around ad 800 to 900 and from about ad 440 to 520. The most prolonged warm, wet period occurred from ad 40 to 400. Some extreme events are shown to correspond well with similar events determined from the Greenland GISP2 ice-core record and elsewhere. Distinct periodicities occur within the record at around 120, 200–300, 500–600 and at about 800 years BP.