Collaborative Research: Quantitative Reconstructions of Last Millennium Hydroclimate and Temperature from the Tropical High Andes

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。地球热带地区的冰川山脉为当地和下游社区提供了重要的淡水资源，并支持丰富多样的生态系统。然而，高海拔地区（12,000英尺）的变暖预计将在未来扩大，预计到世纪中期，许多冰川将消失。比尔卡诺塔山脉（秘鲁）是安第斯山脉第二大冰川山脉，是世界第二大热带冰帽奎尔卡亚的所在地，也是亚马逊河的主要来源。然而，由于仪器记录稀疏，温度和降水量的变化之前，世纪末的约束很差。该项目将利用两个位置接近但截然不同的气候档案：湖泊/泥炭沉积物和冰芯，重建过去几个世纪的温度和湿度可用性模式。湖泊和泥炭沉积物随着时间的推移而积累，保存了过去温度和降水的生物和化学指标。项目可交付成果包括从仪器齐全的安第斯湖泊和泥炭中重建气候，这将提高生物标志物温度代理的实用性，并增强叶蜡和冰芯代理系统模型。 该项目还将支持扩大STEM中代表性不足的群体的参与，并开发K-12教育资源，包括为高中开发气候变化教育模块，并提供实践研讨会，培训和体验式学习机会。研究人员将分析锡比纳科查湖（16，043 '）及其周边地区的沉积物，并使用湖泊和冰模型，校准使用现有的仪器测量，以比较这些重建奎尔卡亚冰帽（QIC）冰芯。结果将提供验证和信息的空气温度，湖泊温度和湿度变化的高安第斯山脉从寒冷时期（小冰期）过渡到工业时期。对过去1,000年的气候模型模拟将说明这些变化在多大程度上是由南美洲夏季季风和热带太平洋海表温度变化等遥远过程驱动的，从而将安第斯目前的气候变化置于长期历史背景中。将生成数据来重建叶蜡中的降水δD（δDprecip）、甘油二烷基甘油四醚（GDGT）中的温度以及岩性、体地球化学和古生态传感器中的径流和降水/蒸发。温度重建将从冰川和非冰川湖泊和泥炭地进行比较，空气/湖泊温度的关系将使用能量平衡模型进行量化。代理系统模型（PSM）将用于评估从冰芯和沉积物中重建的δ 18 O降水、δ D降水和δ D湿地对季节和年均气候变量的敏感性。强迫响应与内部变异性将与同位素启用的最后千年模拟进行研究。由于δ 18 Oice和δDwax都跟踪降水的稳定同位素组成，但对湿度，蒸发和沉积/消融季节的敏感性不同，因此该项目的双PSM方法将允许δ 18 Oprecip，δDprecip，该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用的支持基金会的学术价值和更广泛的影响审查标准。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Glaciated mountain ranges in the Earth’s tropical regions provide critical freshwater resources to local and downstream communities and support richly diverse ecosystems. Yet warming at high elevations (12,000’) is expected to amplify in the future, with the disappearance of many glaciers projected by the mid-21st century. The Cordillera Vilcanota (Peru) is the second largest glacierized mountain range in the Andes, is home to world’s second-largest tropical ice cap, Quelccaya and is a principal source of the Amazon River. However, because instrumental records are sparse, variations in temperature and precipitation prior to the late 20th century are poorly constrained. This project will reconstruct patterns of temperature and moisture availability over the past several centuries using two closely-situated but distinct climate archives: lake/peat sediments and ice cores. Lake and peat sediments accumulate over time, preserving biological and chemical indicators of past temperature and precipitation. Project deliverables include climate reconstructions from well-instrumented Andean lakes and peats, which will imporve the utility of biomarker-based temperature proxies, and enhanced leaf wax and ice cory proxy system models. This project will also support efforts to broaden participation from underrepresented groups in STEM and to develop K-12 educational resources, including development of climate change education modules for high schools, and providing hands-on workshops, training and experiential learning opportunities.Researchers will analyze sediments from sites in and around Lake Sibinacocha (16,043’) and use lake and ice models, calibrated using existing instrumental measurements, to compare these reconstructions to Quelccaya Ice Cap (QIC) ice cores. Results will provide validation and information on air temperature, lake temperature, and moisture changes as the high Andes transitioned from a cold period (the Little Ice Age) to the industrial period. Climate model simulations of the past 1,000 years will contextualize the extent to which these changes were driven by remote processes such as the South American Summer Monsoon and sea surface temperature variations in the tropical Pacific, putting current Andean climate change into a long-term historical context. Data will be generated to reconstruct precipitation δD (δDprecip) from leaf waxes, temperature from glycerol dialkyl glycerol tetraethers (GDGTs), and runoff and precipitation/evaporation from lithologic, bulk geochemical, and paleoecological sensors. Temperature reconstructions will be compared from glacial and non-glacial lakes and peatlands, and air/lake temperature relationships will be quantified using an energy balance model. Proxy system models (PSM) will be used to evaluate the sensitivity of δ18Oprecip, δDprecip, and δDwetland reconstructions from ice cores and sediments to seasonal and mean annual climate variables. Forced responses vs. internal variability will be investigated with isotope-enabled Last Millennium simulations. Because δ18Oice and δDwax both track the stable isotopic composition of precipitation but with differing sensitivities to humidity, evaporation, and seasons of deposition/ablation, the project’s dual-PSM approach will allow multiproxy reconstructions of δ18Oprecip, δDprecip, and temperature while providing new constraints on local evaporative conditions.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.