Testing an abrupt onset of the Little Ice Age

调查人员将收集暴露在加拿大巴芬岛冰川退去边缘的植被，并使用放射性碳测年来确定它在小冰河时代冰川推进时冻结的时间。2005年从同一地点收集的样本表明，冰可能在火山活动后扩大了。这项研究将结合2005年以来冰川消退的距离和苔藓的年龄差异来解决关于降温速度的假设。一名研究生将参与野外工作并准备放射性碳测年结果以供发表。该项目的目标是通过测定加拿大巴芬岛冰川复合体当前冰缘的50个新样本，并将它们与2005年以来的类似收集进行比较，来检验持续小冰期(LIA)寒冷的发病速度。如果LIA的冰层膨胀是突然的和持续的，那么新植物上的日期应该与2005年的样品年龄相同，距离200到500米。然而，如果夏季在整个全新世晚期的几十年到几个世纪里慢慢冷却，那么新的日期将比2005年的对应日期要早得多。总体而言，这些数据将提供对突如其来的LIA寒冷的最有力的测试，并将引起海冰和气候模拟社区的兴趣。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The investigator will collect vegetation exposed along the margins of receding glaciers on Baffin Island, Canada and use radiocarbon dating to determine when it was frozen as glaciers advanced during the Little Ice Age. Samples from the same sites collected in 2005 suggest that ice may have expanded following volcanic activity. This study will address hypotheses about the rate of cooling by combining the distance of ice retreat since 2005 and difference in age of the mosses. A graduate student will participate in field work and prepare results of radiocarbon dating for publication.The goal of this project is to examine the rate of onset of persistent Little Ice Age (LIA) cold by dating 50 new samples from current ice margins from ice complexes in Baffin Island, Canada, and comparing them to similar collections from 2005. If LIA ice expansion was abrupt and persistent then dates on the new plants should be about the same age as the 2005 samples, 200 to 500 m distant. Whereas if summers slowly cooled over decades-to-centuries through the late Holocene, then the new dates will be significantly older than their 2005 counterparts. Collectively, these data will provide the most robust testing of an abrupt onset of LIA cold and will be of interest to the sea ice and climate modeling communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.