A 1500-year record of temperature and glacial response inferred from varved Iceberg Lake, southcentral Alaska
A 1500-year record of temperature and glacial response inferred from varved Iceberg Lake, southcentral Alaska
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DOI：
10.1016/j.yqres.2005.11.007
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发表时间：
2006-07-01
影响因子：
2.3
通讯作者：
Reimer, Paula J.
中科院分区：
文献类型：
--
作者：
Loso, Michael G.;Anderson, Robert S.;Reimer, Paula J.
我们给出了阿拉斯加南部冰原冰山湖冰川厚度年代学。放射成因证据证实，从公元442年到公元1998年，层片每年都有沉积，并记录了连续的沉积。Varve厚度与北半球气温趋势呈正相关，与局地温度变化关系更强，类似于600年长年轮宽度年表。在温暖的夏季，由于更高的融化、径流和沉积物输送(正如预期的那样)，冰川厚度增加，但也因为冰川大坝的收缩允许海岸线倒退，将沉积物集中在较小的湖泊中。Varve厚度提供了暖季温度相对变化的敏感记录。相对于整个记录，这个年表所显示的气温在公元600年左右是最低的，在公元1000年到公元1300年之间是温暖的，在公元1500年到公元1850年之间是凉爽的，从那时起又急剧上升。结合当代(始于1999年)至少自公元442年以来史无前例的地层学证据，这一记录表明，20世纪的变暖比中世纪暖期或过去1500年的任何时候都更加剧烈，并伴随着更大范围的冰川消退。(C)2006年华盛顿大学。版权所有。
We present a varve thickness chronology from glacier-dammed Iceberg Lake in the southern Alaska icefields. Radiogenic evidence confirms that laminations are annual and record continuous sediment deposition from A.D. 442 to A.D. 1998. Varve thickness is positively correlated with Northern Hemisphere temperature trends, and more strongly with a local, similar to 600 yr long tree ring width chronology. Varve thickness increases in warm summers because of higher melt, runoff, and sediment transport (as expected), but also because shrinkage of the glacier dam allows shoreline regression that concentrates sediment in the smaller lake. Varve thickness provides a sensitive record of relative changes in warm season temperatures. Relative to the entire record, temperatures implied by this chronology were lowest around A.D. 600, warm between A.D. 1000 and A.D. 1300, cooler between A.D. 1500 and A.D. 1850, and have increased dramatically since then. Combined with stratigraphic evidence that contemporary jokulhlaups (which began in 1999) are unprecedented since at least A.D. 442, this record suggests that 20th century warming is more intense, and accompanied by more extensive glacier retreat, than the Medieval Warm Period or any other time in the last 1500 yr. (c) 2006 University of Washington. All rights reserved.