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积累的反应，水的可用性将如何变化。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1500万年前的一段时间，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，据预测，随着地球变暖，这一趋势将加剧。然而，最近对中新世气候的重建表明，与过去的温暖时期相关的条件更潮湿，而不是更干燥。该项目旨在了解和模拟中新世温暖气候间隔期间的降雨，以确定水的可用性如何随温度升高而变化。该合作项目支持职业生涯早期和中期的科学家，他们在乔治梅森大学提供气候建模的研究生和高中培训，并在南加州大学提供气候重建的研究生和本科生培训。研究结果正在通过在弗吉尼亚州和宾夕法尼亚州的自然中心举办的社区讲座以及与南加州大学通信学院和洛杉矶县自然历史博物馆的中新世气候展览的合作与公众分享。该研究的目的是解决持续的水文气候不确定性在气候变暖的模式数据集成的方法。低分辨率气候模拟测试水文气候对海洋温度重建的响应以及对代理不确定性和覆盖范围的敏感性。高分辨率模拟更好地解决了北美季风和大气河流，这决定了极端降水事件和随后的潮湿气候状态，而不是当前和预测的干燥趋势。旨在填补数据缺口，了解美国西部水文气候，该项目产生额外的代理重建海洋温度和陆地水文气候。从地质、植物和动物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，用于与气候模型和一般科学界进行比较。这种模型替代方法阐明了未来气候变化的过程、敏感性和临界点，包括随着气候变暖从干燥环境向湿润环境的可能转变。该奖项反映了NSF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。

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.