Terrestrial fossil-pollen evidence of climate change during the last 26 thousand years in Southern Africa
Terrestrial fossil-pollen evidence of climate change during the last 26 thousand years in Southern Africa
复制标题
南部非洲过去 26000 年气候变化的陆地化石花粉证据
DOI：
10.1016/j.quascirev.2011.11.010
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发表时间：
2012
影响因子：
4
通讯作者：
Amr A. Metwally
中科院分区：
文献类型：
--
作者：
L. Scott;F. Neumann;G. Brook;C. Bousman;E. Norström;Amr A. Metwally
为了确定南部非洲长期气候变化模型的标准，需要对晚第四纪的花粉资料进行概述。在这里，我们通过综合现有的化石花粉数据来重新评估非洲南部的古气候条件，这些数据可以为环境变化过程提供新的见解。这里考虑的数据包括最新的和以前公布的难以评估的信息。通过主成分分析（PCA），监测了华北地区晚更新世和全新世的花粉序列对湿度和温度波动的敏感性。PCA值以图形形式表示为该地区气候变率的指标。结果涵盖了不同的生物群系，包括北部和东部的夏雨区，南部的冬雨区和西部的干旱区。主成分分析图直接反映了由于温度和湿度变化引起的陆地环境的主要变化。在寒冷的海洋同位素阶段（MIS） 2期间，次大陆北部、中部和东部在全新世开始后不久至中全新世之前出现了一个干燥阶段，主要是半湿润但波动的条件。在全新世期间，不同亚区出现了明显但不平行的湿度变化，表明整个地区的气候强迫并不均匀。有些事件似乎对次大陆的影响更为均匀，例如，2000年前c.相对干燥的夏季降雨事件，这可能与ENSO现象有关。在最近的一些植被变化中，人类活动的作用是可能的。
In order to define criteria for long-term climate change models in Southern Africa, an overview of the available pollen data during the Late Quaternary is needed. Here we reassess the paleo-climatic conditions in southern Africa by synthesising available fossil pollen data that can provide new insights in environmental change processes. The data considered here include the latest as well as previously published information that has been difficult to assess. Available calibrated pollen sequences spanning the Late Pleistocene and Holocene were subjected to Principal Components Analysis (PCA) to monitor taxa sensitive to moisture and temperature fluctuations. The PCA values are presented graphically as indicators of climate variability for the region. The results cover different biomes that include the summer-rain region in the north and east, the winter-rain area in the south and the dry zone in the west. The PCA plots directly reflect major changes of terrestrial environments due to variations in temperature and moisture. Mostly sub-humid but fluctuating conditions are indicated during the cold Marine Isotope Stage (MIS) 2, which were followed by a dry phase soon after the beginning of the Holocene but before the middle Holocene in the northern, central and eastern parts of the sub-continent. Marked but non-parallel moisture changes occurred in different subregions during the Holocene suggesting that climatic forcing was not uniform over the entire region. Some events seemed to have had a more uniform effect over the sub-continent, e.g., a relatively dry summer rain event at c. two thousand years ago, which can possibly be related to the ENSO phenomenon. The role of anthropogenic activities in some of the most recent vegetation shifts is likely.