摘要
在当前全球变化背景下,青藏高原冰川急剧退缩严重影响着东亚地区水资源。为了有效地规划水资源,需要对高原气候变化及其机制有深入的理解。尽管在青藏高原及周边地区有大量的古气候记录,但是目前对高原气候的时空变化及其机制仍缺乏深入一致的认识。青藏高原冰川、树轮和石笋记录可以提供过去气候变化的框架,但是这些记录的分布局限于一些特定的地理区域。青藏高原上广泛分布的湖泊沉积物是研究高原气候的时空变化及其机制的优良介质。湖泊沉积物岩芯的年龄控制主要依赖于放射性碳同位素定年,但大多数高原湖泊具有碳库效应,为建立沉积岩芯年代控制需要进行碳库年龄校正所带来的年龄误差目前未有深入研究,这在某种程度上制约了利用湖泊沉积物记录研究高原气候时空变化及其机制。本文比较了目前确定高原湖泊碳库年龄的方法并提出建议采用的方法,汇总目前已发表的高原湖泊碳库年龄,讨论湖泊现代碳库年龄的空间分布及其影响因素,讨论湖泊碳库过去变化及其可能造成的岩芯年代控制误差;以青海湖和班公错两个高原湖泊已发表的记录为例讨论过去碳库年龄变化可能造成对记录完全不同的解释;还讨论了由碳库效应校正而带来的湖泊沉积物岩芯年龄控制误差对青藏高原湖泊记录的末次盛冰期终止年代的空间分布及其对变化机制解释的影响。如果考虑碳库效应的过去变化,目前所观测到的高原气候时空变化及其机制需要重新解释。因此,为了更好地理解青藏高原气候时空变化及其机制,我们需要更多有良好定年、高分辨率和定量化的湖泊记录,本文也建议在解释目前湖泊记录时需要应对年龄控制极大重视。
The Tibetan Plateau is often referred to as the Earth＇s Third Pole, due to its great elevation, massive size,large quantities of terrestrial ice and its impact on northern Hemisphere weather patterns. Concern surrounding the impact of anthropogenic global warming on the ice fields of the Tibetan Plateau and the need for accurate projections of future climate have reinvigorated interest in understanding the dynamics that control the climate of the TP. Present day climate on the Tibetan Plateau is chiefly influenced by the East Asian Monsoon, the Indian Monsoon and the circulation of the mid-latitude Westerlies. Despite the large number of paleoclimate records from the region, the spatial patterns of past changes in Tibetan Plateau climate and the associated forcing mechanisms remain poorly understood. Existing paleoclimate records from ice cores, speleothems and tree rings provide a framework for examining past climate dynamics on the TP, but with limited geographical coverage. Lake sediments offer opportunities for higher spatial resolution of paleoclimate records, but inaccuracy of radiocarbon-based age models of sediment accumulation represents a fundamental restriction on the utility of lake-based paleoclimate records. In this paper,we review the techniques used to estimate reservoir ages of lake sediments from the Tibetan Plateau. We demonstrate that uncertainties in 14C reservoir ages allow equally probable and contrasting interpretations of paleoclimate records from the Tibetan Plateau. More well-dated, high-resolution, quantitative lacustrine records are needed to confidently interpret the mechanisms for the past climate variability on the Tibetan Plateau and we recommend that the full impacts of chronological uncertainty be considered when interpreting existing lake-based paleoclimate records.
出处
《第四纪研究》
CAS
CSCD
北大核心
2012年第3期441-453,共13页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41072120)
中国科学院知识创新工程项目(批准号:KZCX2-YW-JC106)
中国科学院地球环境研究所黄土与国家重点实验室开放基金项目(批准号:SKLLQG0917)
中国科学院"百人计划"项目共同资助
