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

该项目使用资金进行为期两年的试点研究，以探索可能存储在冰芯中的古气候信息，冰芯是从新墨西哥州西部的El Malpais国家纪念碑（ELMA）的选定数量的熔岩管中回收的，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）敏感，厄尔尼诺南方涛动（ENSO）和北美季风系统（NAMS）之间的相互作用。 更深入地了解这些模式的过去（前仪器）的行为可能有助于改善未来干旱和洪水周期的预测。 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日期明确的记录，这将检验一个总体假设，即ENSO和NAMS变化在过去的几千年里在西南部是持续的特征，所有主要的气候时期（例如，本项目的目的是：1）为在碳酸盐不能用于δ 18-氧分析的熔岩管中使用冰沉积物的稳定同位素组成提供概念证明;（二）有助于定量古气候数据集的不断增长的网络，这将增加一个关键的空间和时间的角度来理解干旱模式在北美西南部和相关的天气气候遥相关;和3）开发高分辨率，十年到十年尺度的同位素记录，从冰在西南熔岩管在过去的3,000年。 该项目还可能有助于解决其他重要的科学问题，如：1）冰中过量的δ 18-氧和氘如何表明冰形成过程中水分来源和空气温度的变化？2)冰的稳定同位素组成是如何反映美国西南部的水文气候变化的？在过去的3000年里，气候变化的大尺度模式是什么？3）冰沉积是否可以用来识别西南地区晚全新世干旱（特大干旱）的空间格局。 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定年木炭和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支持一名研究生，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，该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.