Pilot Project: Exploring the Paleoenvironmental Data Archived in Ice Deposits from Lava Tubes before Its Imminent Loss to Ice Melting

该项目利用资金进行为期两年的试点研究，探索可能储存在新墨西哥州西部埃尔马尔佩斯国家纪念碑 (ELMA) 选定数量的熔岩管中的冰芯中的古气候信息，该地区是干旱研究的巨大潜力地区。仪器气候记录表明，北美西南部的干旱模式对太平洋年代际海洋 (PDO) 变化以及厄尔尼诺南方涛动 (ENSO) 与北美季风系统之间的相互作用敏感。 （NAMS）。 更深入地了解这些模式过去（工具出现前）的行为可能有助于改善对未来干旱和雨季周期的预测。 熔岩管中季节性积累的冰可以提供气候条件变化的高分辨率和详细的日期记录，这将检验总体假设，即 ENSO 和 NAMS 变化是西南地区过去几千年的持续特征，并且所有主要气候时期（例如中世纪温暖期）都是这种年代际到年代际变化模式的一部分。该项目旨在：1）为冰的稳定同位素成分的使用提供概念证明熔岩管中的沉积物无法用于 Delta 18 氧分析； 2) 为不断增长的定量古气候数据集网络做出贡献，这将为理解北美西南部的干旱模式和相关的天气气候遥相关增加关键的空间和时间视角； 3) 开发过去 3,000 年来西南部熔岩管中的冰的高分辨率、年代际到年代际尺度的同位素记录。 该项目还可能有助于解决其他重要的科学问题，例如：1）冰的δ18-氧和氘过量如何表明冰形成过程中水分源和空气温度的变化？ 2) 冰的稳定同位素组成如何反映美国西南部的水文气候变化以及过去 3000 年中哪些大规模的气候变化模式在起作用？ 3）冰沉积物能否用于识别全新世晚期西南地区干旱（特大干旱）的空间模式。 为了解决这些问题，冰同位素记录将与从冰中回收的放射性碳测年木炭以及 ELMA 提供的高分辨率树木年轮数据结合使用。潜在的更广泛影响包括对研究生的支持、开发新的古气候数据档案的潜力以及美国西南部干旱科学的进步，这是当前和未来水资源关注的领域。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

This project uses funding for a two-year pilot study to explore the paleoclimate information potentially stored in ice cores recovered from a select number of lava tubes from El Malpais National Monument (ELMA) in western New Mexico, a region of great potential for drought research.Instrumental climate records indicate that drought patterns in southwestern North America are sensitive to Pacific Decadal Ocean (PDO) variability and to interactions between the El Niño Southern Oscillation (ENSO) and the North American Monsoon System (NAMS). A deeper understanding of the past (pre-instrumental) behavior of these modes could be helpful for improving predictions of future drought and pluvial cycles. Seasonally-accumulated ice in lava tubes may provide an high-resolution and well-dated record of changing climatic conditions that will test the overarching hypothesis that ENSO and NAMS variability were persistent features over the past millennia in the Southwest and that all major climate periods (e.g., Medieval Warm Period) were part of this pattern of decadal-to-interdecadal variability.This project aims to: 1) provide proof of concept for the use of stable isotopic composition of ice deposits in lava tubes where carbonates are not available for delta 18-Oxygen analyses; 2) contribute to a growing network of quantitative paleoclimate datasets that would add a critical spatial and temporal perspective to the understanding of aridity patterns in southwestern North America and associated synoptic climate teleconnections; and 3) develop high-resolution, decadal-to-interdecadal scale isotopic records from ice in lava tubes in the Southwest for the past 3,000 years. The project may also help address other important science questions such as: 1) How delta 18-Oxygen and deuterium excess of ice indicate changes in the moisture source and air temperature during ice formation? 2) How is hydroclimate variability in the south west U.S. reflected by the stable isotopic composition of ice and which of the large-scale modes of climate variability were operating over the past 3000 years? and 3) Can ice deposits be used to identify spatial patterns of aridity (megadroughts) in the Southwest during late Holocene. To address these questions, the ice isotopic record will be used in conjunction with radiocarbon dated charcoal recovered from ice and high-resolution tree-ring data available at ELMA.The potential Broader Impacts include support for a graduate student, the potential for developing a new archive of paleoclimate data, and the advancement of the science of drought in the southwestern U.S., an area of concern for current and future water resources.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.