Collaborative Research: Characterizing the drivers of hydroclimate change over western North America and Europe in response to the global warmth of the middle Miocene

社会面临的一个关键问题是，随着地球气候系统对温室气体的积累做出反应，水资源的可获得性将如何变化。为了解决这个问题，一组研究人员正在调查中新世中期的环境条件，这是大约1500万年前的间隔，当时地球处于温暖的气候状态。近几十年来，美国西部和欧洲经历了干旱，预计随着地球变暖，这一趋势将会加剧。然而，最近对中新世气候的重建表明，与过去的温暖时段有关的条件更潮湿，而不是更干燥。该项目旨在了解和模拟中新世气候变暖期间的降雨，以确定水的可获得性如何随气温变暖而变化。该合作项目支持职业生涯早期和中期的科学家，他们为乔治梅森大学的气候建模提供研究生和高中实习生职位，并为南加州大学提供气候重建方面的研究生和本科生实习生职位。研究成果正在通过弗吉尼亚州和宾夕法尼亚州自然中心的社区讲座以及与南加州大学传播学院和洛杉矶县自然历史博物馆的中新世气候展览合作与公众分享。本研究旨在通过模式-数据集成的方法来解决气候变暖中持续存在的水文气候不确定性。低分辨率气候模拟测试了水文气候对海洋温度重建的反应，以及对替代不确定性和覆盖面的敏感性。高分辨率模拟更好地解析了北美季风和大气河流，它们关键地决定了极端降水事件和随后更潮湿的气候状态，而不是当前和预测的干旱趋势。为了填补了解美国西部水气候的数据空白，该项目生成了更多的海洋温度和陆地水气候的替代重建。从地质、植物和动物群记录中提取的水文气候证据被处理成一个可用的数据框架，以便与气候模型和一般科学界进行比较。这种模型-代理方法阐明了我们未来气候变化的过程、敏感性和临界点，包括可能随着气候变暖而从更干燥的环境转变为更潮湿的环境。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A key question facing society is how will water availability change as the Earth’s climate system responds to the accumulation of greenhouse gases. To address this question, a team of researchers are investigating the environmental conditions during the mid-Miocene, an interval around 15 million years ago, when the planet was in a warm climate state. The western US and Europe have experienced drying in recent decades, a trend that has been forecast to intensify as our planet warms. However, recent reconstructions of Miocene climate suggest wetter rather than drier conditions associated with past warm intervals. This project aims to understand and model rainfall during warm climate intervals in the Miocene to determine how water availability may change with warming temperatures. The collaborative project supports early career and mid-career scientists who provide graduate and high school traineeships for climate modeling at George Mason University and graduate and undergraduate traineeships in climate reconstruction at the University of Southern California. Research findings are being shared with the public through community lectures at nature centers in Virginia and Pennsylvania as well as via a partnership with University of Southern California’s communication school and the Natural History Museum of Los Angeles County’s Miocene climate exhibit. The research aims to resolve the persistent hydroclimate uncertainty in a warming climate with a model-data integration approach. Low-resolution climate simulations test hydroclimate response to ocean temperature reconstructions and sensitivity to proxy uncertainty and coverage. High-resolution simulations better resolve the North American Monsoon and atmospheric rivers, which critically determine extreme precipitation events and the subsequent wetter climate state than the current and projected drying trends. Aiming to fill data gaps for understanding western US hydroclimate, the project generates additional proxy reconstructions of ocean temperature and terrestrial hydroclimate. Extracted hydroclimate evidence from geological, botanical, and faunal records are processed into a usable data framework for comparison to climate models and the general scientific community. This model-proxy approach illuminates processes, sensitivities, and tipping points in our climate future, including a possible shift from a drier to wetter environment with warming.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.