小冰期以来横断山区冰川波动历史的树轮重建及其与气候变化的关系

树木年轮 冰川波动 小冰期 冰碛垄 海洋型冰川
徐鹏 2014-01 项目
Research on the relationship between glacier fluctuations and climate changes on decadal to centennial time scales, which is of great significance for our understanding on the changes of global cryosphere, is greatly limited by the lack of sufficient observational data on glaciers and climate changes. Hengduan mountains is one of the distribution centres of maritime glaciers in China, where dendroglaciological evidences for glacier advances/retreats, glacial moraines and tree-ring materials formed since the Little Ice Age(LIA), were well kept. This study intends to:(1) reconstruct the fluctuation history of glaciers in Hengduan mountains through analyzing tree-ring materials sampled from relict wood and tilted trees directly affected by the glacial movement, and dating the moraines based on the age of the oldest tree growing on morainic surface, with an adjustment for the pith offset, age error of sampling height and ecesis time; (2) reconstruct the past temperature and precipitation variations using tree rings sampled from upper forest limit and mountain forest-dry valley ecotone, separately; (3) reveal the relationship between LIA glacier fluctuations and climate changes. The results of this study will contribute to the understanding on the relationship between glacier fluctuations and climate changes on decadal to centennial time scales, and provide useful knowledge for the prediction of glacier change under future climate scenarios.
冰川变化及其与气候变化关系的研究对全球冰冻圈变化的认识具有重要的科学意义。但冰川变化和气候变化观测资料稀缺而且记录时间很短,这限制了我们对几十年至百年时间尺度上冰川波动及其与气候变化关系的认识。本项目拟以横断山区海洋型山谷冰川为研究对象,利用冰川末端谷地中采集的树木年轮资料,包括冰碛中的残遗木、谷地两侧的倾斜木和冰碛垄上的最老活树样本等,结合冰川地貌证据,对该地区冰川进退波动历史进行重建;并尝试利用冰川区附近山地森林上限和山地森林-干旱河谷交错带的树轮资料分别重建能够完全覆盖小冰期的气温变化序列和降水变化序列;进而探讨过去几百年横断山区海洋型冰川进退波动对气温和降水变化的响应关系。本研究的结果将有助于长时间尺度上对海洋型冰川进退波动与气候变化关系的认识,为预估未来气候变化情景下冰川变化提供科学依据和基本数据。