传统的孢粉-古气候定量重建评估主要衡量校准集对现代气候状况的模拟结果或化石样品与校准集样品的可比程度,客观上导致特定地点重建气候参数的取舍缺少明确标准.基于国际上通过随机数据开展定量重建显著性检验的新方法,充分利用中国环...传统的孢粉-古气候定量重建评估主要衡量校准集对现代气候状况的模拟结果或化石样品与校准集样品的可比程度,客观上导致特定地点重建气候参数的取舍缺少明确标准.基于国际上通过随机数据开展定量重建显著性检验的新方法,充分利用中国环境梯度大、植被类型丰富、现代表土孢粉数据完善等优势,提出一种孢粉-古气候参数定量重建的新思路:首先确定控制化石孢粉组成变化最主要环境因子,随后通过限制其他环境因子来构造校准集以开展该因子的定量重建,最后完成重建结果显著性评估.将该思路应用于分别位于黄土高原东、西两侧的吕梁山公海和六盘山天池化石孢粉序列,所获得的年降水量P_(ann)定量重建不仅具有统计上的显著性(p<0.001),且相互间在共同时段表现出良好、稳定的相关关系,均指示了约3300cal a BP以来的东亚夏季风降水快速下降,显示其具备降低基于孢粉的古气候参数定量重建不确定性的较大潜力.展开更多
Asian dust storms have long been a major environmental concern in China,affecting the lives of about one billion people.However,it is unclear whether the mechanisms responsible for Asian dust storms during the Holocen...Asian dust storms have long been a major environmental concern in China,affecting the lives of about one billion people.However,it is unclear whether the mechanisms responsible for Asian dust storms during the Holocene varied on different timescales,and thus it is unclear whether there was a shift from a natural forcing to an anthropogenic forcing of dust storms.We reconstructed a high-resolution Holocene record of dust storms from the sediments of an undisturbed alpine lake on the Chinese Loess Plateau.We found that Asian dust storm activity generally increased during the Holocene,with the largest fluctuations occurring during the past 2000 years.The increase in dust storm activity was in contrast to the decrease in East Asian winter monsoon(EAWM)intensity during the Holocene,indicating that the EAWM played a limited role in modulating dust storms.By contrast,the increase in dust storms corresponded to a decrease in East Asian summer monsoon(EASM)precipitation.This demonstrates that EASM precipitation was the dominant control of dust storm activity on a millennial timescale,because decreased EASM precipitation expanded the desert area and thus increased the dust storm activity.The increasing intensity of human activity in the region since the Bronze Age resulted in an acceleration of dust storm activity against the background of decreased EASM precipitation.As human disturbance continued to intensify,beginning at least at~2 cal ka BP,increased dust storms were closely linked to increasing human populations in the dust source regions,and there is a strong temporal coherence between increased dust storms and higher EASM precipitation.This was completely different from when natural processes are dominant.During that period,fewer dust storms occurred during periods of a strengthened EASM.Therefore,there was a shift from a natural forcing to an anthropogenic forcing of dust storms on a multi-decadal to centennial timescale,and was a mode in which‘‘human activity overtook the EASM as the dominant control of the Ea展开更多
文摘传统的孢粉-古气候定量重建评估主要衡量校准集对现代气候状况的模拟结果或化石样品与校准集样品的可比程度,客观上导致特定地点重建气候参数的取舍缺少明确标准.基于国际上通过随机数据开展定量重建显著性检验的新方法,充分利用中国环境梯度大、植被类型丰富、现代表土孢粉数据完善等优势,提出一种孢粉-古气候参数定量重建的新思路:首先确定控制化石孢粉组成变化最主要环境因子,随后通过限制其他环境因子来构造校准集以开展该因子的定量重建,最后完成重建结果显著性评估.将该思路应用于分别位于黄土高原东、西两侧的吕梁山公海和六盘山天池化石孢粉序列,所获得的年降水量P_(ann)定量重建不仅具有统计上的显著性(p<0.001),且相互间在共同时段表现出良好、稳定的相关关系,均指示了约3300cal a BP以来的东亚夏季风降水快速下降,显示其具备降低基于孢粉的古气候参数定量重建不确定性的较大潜力.
基金supported by the National Natural Science Foundation of China(41790421,41722105,41988101)。
文摘Asian dust storms have long been a major environmental concern in China,affecting the lives of about one billion people.However,it is unclear whether the mechanisms responsible for Asian dust storms during the Holocene varied on different timescales,and thus it is unclear whether there was a shift from a natural forcing to an anthropogenic forcing of dust storms.We reconstructed a high-resolution Holocene record of dust storms from the sediments of an undisturbed alpine lake on the Chinese Loess Plateau.We found that Asian dust storm activity generally increased during the Holocene,with the largest fluctuations occurring during the past 2000 years.The increase in dust storm activity was in contrast to the decrease in East Asian winter monsoon(EAWM)intensity during the Holocene,indicating that the EAWM played a limited role in modulating dust storms.By contrast,the increase in dust storms corresponded to a decrease in East Asian summer monsoon(EASM)precipitation.This demonstrates that EASM precipitation was the dominant control of dust storm activity on a millennial timescale,because decreased EASM precipitation expanded the desert area and thus increased the dust storm activity.The increasing intensity of human activity in the region since the Bronze Age resulted in an acceleration of dust storm activity against the background of decreased EASM precipitation.As human disturbance continued to intensify,beginning at least at~2 cal ka BP,increased dust storms were closely linked to increasing human populations in the dust source regions,and there is a strong temporal coherence between increased dust storms and higher EASM precipitation.This was completely different from when natural processes are dominant.During that period,fewer dust storms occurred during periods of a strengthened EASM.Therefore,there was a shift from a natural forcing to an anthropogenic forcing of dust storms on a multi-decadal to centennial timescale,and was a mode in which‘‘human activity overtook the EASM as the dominant control of the Ea
