Testing an abrupt onset of the Little Ice Age

研究人员将收集加拿大巴芬岛冰川消退边缘裸露的植被，并使用放射性碳定年法来确定在小冰河期冰川推进时，这些植被是何时被冻结的。2005年从同一地点采集的样本表明，火山活动后冰可能已经扩大。这项研究将通过结合2005年以来冰川退缩的距离和苔藓年龄的差异来解决关于冷却速度的假设。一名研究生将参加实地工作，并准备放射性碳定年的结果供发表。该项目的目标是通过对加拿大巴芬岛冰群目前冰缘的50个新样本进行测年，并将它们与2005年的类似收集进行比较，来检查持续小冰期（LIA）寒冷的开始率。如果LIA冰的扩张是突然和持续的，那么新植物的年代应该与2005年样本的年代大致相同，距离200到500米。然而，如果夏季在全新世晚期的几十年到几个世纪里慢慢变冷，那么新的日期将比2005年的日期要早得多。总的来说，这些数据将为LIA寒冷的突然发生提供最可靠的测试，并将对海冰和气候建模社区产生兴趣。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.