CAREER: Quantifying climate induced landscape evolution during early Eocene hyperthermals

自上世纪80年代以来，美国因与人为气候变化有关的极端降水事件造成了数十亿美元的损失。这些事件造成的侵蚀和沉积物的增加可能会破坏土壤，堵塞河流，破坏水利基础设施。然而，我们对河流和景观对全球气候变化的反应程度知之甚少，因为这些变化发生的时间尺度很难在我们有生之年测量。因此，我们必须着眼于地球过去温度和大气二氧化碳浓度迅速上升的时期，以研究景观响应。在始新世早期，大约5600万到5200万年前，出现了被称为过热事件的重复间隔，在大约2万年的时间里，由于二氧化碳的释放，全球气温迅速上升。这些超热现象提供了与现代人为气候变化最好的类比之一，尽管速度比今天慢。该项目将通过使用新墨西哥州、怀俄明州和北达科他州始新世早期的类似物，重点提高科学和公众对未来气候变化将如何影响我们的河流系统的理解。该教育计划将针对来自休斯顿大学的不同学生群体，通过虚拟实地考察，加强本科生对野外地质学的接触。由于气候变化对某些群体来说是一个抽象而令人生畏的概念，因此与世界知名的气候艺术家合作将被用来打破心理障碍，并向公众、休斯顿地区的低收入和少数民族学生传播科学。该项目将从美国西部三个河流主导的盆地生成新的陆地古气候记录：1)新墨西哥州的圣胡安盆地，2)怀俄明州的风河盆地，3)北达科他州的威利斯顿盆地。它将使用一种新颖的方法，将砂岩水道相和洪泛平原古土壤的数据集整合在一起，以测试热驱动的水文循环加剧与形成大型砂体和厚高岭石包的风化作用之间的假设联系。该项目将采用多代理方法，包括地球化学、矿物学、稳定同位素（δ13C、δ18O和Δ47）、沉积学、地层学、放射性同位素年代学（40Ar/39Ar、U-Th-Pb）和磁地层学，重建古气候，并在空间和时间上约束景观对高温事件的响应。由此产生的数据集将被整合到定量模型中，以测试大气二氧化碳增加的速度、全球变暖以及由此产生的水文循环加剧将增加风化和沉积物产生的程度，这有可能因土壤流失、侵蚀和洪水增加而对基础设施和生态系统造成数十亿美元的损失。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 US has incurred billions of dollars in damage from extreme precipitation events linked to anthropogenic climate change since the 1980s. Increased erosion and sediment yield from these events is likely to damage soils, clog rivers, and cripple hydraulic infrastructure. However, we have little information on the magnitude of the response of our rivers and landscapes to global climate change because these changes occur on timescales difficult to measure in our lifetimes. Therefore, we must look to times in Earth’s past when temperatures and atmospheric CO¬2 concentrations rose rapidly to study landscape response. During the early Eocene, approximately 56 to 52 million years ago, there were repeated intervals known as hyperthermal events where global temperatures rapidly increased due to releases of CO2 over a period of ~20,000 years. These hyperthermals provide one of the best analogs to modern anthropogenic climate change, albeit at a slower rate than today. This project will focus on improving scientific and public understanding of how future climate change will affect our river systems by using analogs from the early Eocene in New Mexico, Wyoming, and North Dakota. The education plan will target a diverse population of students from the University of Houston that will strengthen undergraduate exposure to field geology using virtual field trips. Because climate change can be an abstract and intimidating concept for some groups, collaborations with a world-renowned climate-artist will be used to break down mental barriers and communicate science to the public and low-income and minority students from the Houston area. This project will generate new terrestrial paleoclimate records from three fluvially dominated basins in the western US: 1) San Juan Basin of New Mexico, 2) Wind River Basin of Wyoming, and 3) Williston Basin of North Dakota. It will use a novel method that integrates datasets from both sandstone channel facies and floodplain paleosols to test the hypothesized connection between hyperthermal-driven hydrologic cycle intensification and increased weathering that formed large sand bodies and thick packages of kaolinite. This project will use a multi-proxy approach that includes geochemistry, mineralogy, stable isotopes (δ13C, δ18O, and Δ47), sedimentology, stratigraphy, radiogenic isotope geochronology (40Ar/39Ar, U-Th-Pb), and magnetostratigraphy to reconstruct the paleoclimate and constrain landscape response to the hyperthermal events both spatially and temporally. The resulting dataset will be integrated into quantitative models to test how rapid atmospheric CO2 increases, global warming, and the resulting hydrologic cycle intensification will increase the magnitude of weathering and sediment yield, which has the potential to cause billions of dollars in damage to infrastructure and ecosystems from soil loss, erosion, and increased flooding.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.