Collaborative Research: Toward placing contemporary Arctic summer warming in a millennial perspective with a pan-Arctic record of Neoglacial crysophere expansion

米勒/考夫曼：从千年的角度看当代北极夏季变暖与新冰川期冰圈扩张的泛北极记录非技术摘要。北极冰川的规模是由夏季气温决定的，但阿拉斯加冰川自冰河时代结束以来的规模变化却很少受到限制。为了应对最近的北极变暖，阿拉斯加布鲁克斯山脉的冰川正在迅速消退，在特殊的环境下，在冰很薄的缓坡上，冰川起着保护剂而不是腐蚀剂的作用，保存着在遥远的过去冰扩展到该地区之前生长的完整的苔原小植物。这个项目的目标是参观布鲁克斯山脉最有可能的地点，在那里冰川被保存下来，而不是被侵蚀，我们预计苔原植物会随着冰的消退而重新暴露出来。这些植物的放射性碳年龄记录了过去的夏季何时变得更冷，使冰在这些地点扩张，并提供了过去北极夏季何时冷却到足以让冰川生长的最可靠证据。更广泛的影响。将阿拉斯加冰埋植物的年龄与北极其他地区暴露植物的年龄进行比较，将使我们更好地了解半球范围内的大规模气候变化。这些结果可作为用于预测未来气候的气候模型的检验。用于预测未来的相同模型也可以反向运行来预测过去的气候演变。如果模型预测的过去气候变化模式与北极地区冰埋植物年代记录的相似，那么我们对气候模型可靠预测未来气候能力的信心就会增加。如果这些模型不能预测类似于植物年龄的模式，那么很可能这些模型低估了气候系统的某些方面。技术总结。全新世期间布鲁克斯山脉冰川规模的变化是夏季气温变化的主要指标，但其变化受到的约束很差。在冰川寒冷、地势平缓的地方，它们通常不会受到侵蚀，而是作为一种特殊的保护剂，保存着被膨胀的冰杀死的苔原上的小植物。布鲁克斯山脉的冰川迅速消退，现在暴露出的景观很可能保留了被全新世晚期冰川扩张杀死的原冻原植物，它们的放射性碳年龄决定了持续寒冷的夏季。该项目将访问最有希望的地点，寻找随着冰缘消退而出现的冰埋植物，并利用美国国家科学基金会支持的北亚利桑那大学新加速器质谱仪进行年代测定。我们期望得到的年代植物的复合概率密度函数能够产生反映冰膨胀/寒冷夏季事件的年龄群，这可以与北大西洋北极地区的结果进行比较，并共同作为cip -6正在进行的普通时代气候模型的目标。更广泛的影响。随着气候变化的加速和气候素养的滞后，与更广泛的公众沟通气候变化比以往任何时候都更加重要。尽管人们普遍认为阿拉斯加（和其他地方）的冰川正在迅速消退，但人们对这次衰退到底有多不寻常却知之甚少。这项研究将把冰川衰退放在千年的角度，可能说明当前的变暖是几千年来前所未有的，这是一个很容易被公众理解的概念。为了促进公众宣传，我们将支持一位经验丰富的平面设计师将我们的科学转化为阿拉斯加公民和更广泛的美国社区可以访问的形式。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。

Miller/Kaufman: Toward placing contemporary Arctic summer warming in a millennial perspective with a pan- Arctic record of Neoglacial crysophere expansionNon-technical summary. Glacier dimensions in the Arctic are set by summer temperature, but changes in the dimensions of Alaskan glaciers since the end of the ice age are poorly constrained. In response to recent Arctic warming, glaciers in the Brooks Range, Alaska are receding rapidly, and in special settings, on gentle slopes where the ice is thin, glaciers act as preservation agents, rather than erosive agents, preserving intact tiny tundra plants living before the ice expanded over that site in the distant past. The goal of this project is to visit the most likely sites in the Brooks Range where glaciers preserved, rather than eroded the landscape, where we expect tundra plants are being re-exposed as ice recedes. The radiocarbon ages of these plants document when past summers grew colder, allowing ice to expand across these sites, and provide the most reliableevidence of when in the past Arctic summers cooled enough to allow glaciers to grow.Broader Impacts. Comparing the ages of ice-entombed Alaska plants to ages of plants exposed in other Arctic regions will allow us to better understand large-scale climate change on a hemispheric scale. These results serve as tests for climate models that are used to predict future climate. The same models used for future projections can be run in reverse to predict climate evolution in the past. If the models predict similar patterns of past climate change as documented by the ages of ice-entombed plants across the Arctic, our confidence in the ability of climate models to reliably predict future climate is increased. If the models fail to predict patterns similar to the plant ages, then it is likely the models have underestimated certain aspects of the climate system.Technical summary. Changes in the dimensions of Brooks Range glaciers through the Holocene, a primary proxy for changes in summer temperature, are poorly constrained. Where glaciers are cold-based and on gently sloping terrain, they often do not erode, but act as exceptional preservation agents, preserving tiny tundra plants killed by expanding ice. Rapid ice recession across the Brooks Range is now exposing landscapes likely to preserve in situ tundra plants killed by late Holocene ice expansion, with their radiocarbon ages defining episodes of consistently cold summers. This project will visit the most promising sites to look for iceentombed plants emerging as the ice margins recede, and take advantage of the new NSF-supported accelerator mass spectrometer at Northern Arizona University for dating. We expect the resultant composite probability density functions of dated plants to produce age clusters reflecting episodes of ice expansion/cold summers, which can be compared with results from the North Atlantic Arctic, and collectively serve as targets for Common Era climate modeling now underway with CMIP-6.Broader Impacts. Communicating climate change with the wider public is more important than ever as climate change accelerates and climate literacy lags. Although it's widely understood that glaciers in Alaska (and elsewhere) are rapidly receding, there is less understanding of how unusual this recession really is. This study will place glacier recession in a millennial perspective, likely illustrating that current warming is unprecedented over thousands of years, a concept easily grasped by the general public. To advance public outreach, we will support an experienced graphic designer to translate our science to a form that is accessible to the citizens of Alaska and the broader US community.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.