Collaborative Research: Paleoclimate perspective on the response of Southwest North American rainfall to elevated greenhouse gases

合作研究：北美西南部降雨对温室气体升高的响应的古气候视角

• 批准号: 1903650
• 负责人: Ran Feng
• 金额: $ 14.95万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1903650&HistoricalAwards=false
• 关键词: Collaborative; Research; Paleoclimate; perspective; response

In recent years, severe drought in southwestern North America has prompted intense interest in understanding the future trajectory of hydroclimate in this vulnerable region. Studying past greenhouse climates can help identify the processes that might drive future rainfall changes in the Southwest. One such interval, the mid-Pliocene Warm Period, which occurred 3.3 million years ago and featured CO2 concentrations similar to near-future values, presents an interesting conundrum. Simulations of the Pliocene suggest widespread dry conditions across the Southwest, just as models predict drying across much of the southwest by the end of the 21st century. However, multiple lines of geological evidence suggest wetter conditions in the Pliocene. This research project aims to resolve this apparent paradox using a combination of state-of-the-art, high-resolution climate model simulations and new reconstructions of southwestern rainfall spanning the Pliocene to the present. The reconstructions will provide some of the first constraints on the Pliocene history of regional climate features like the North American Monsoon. These data and model simulations will be used to evaluate sources of bias in model simulations of the Pliocene and to understand how this past interval of climate change may have differed from current warming. The project has direct applications to improving projections of southwestern rainfall in a warming world. The results of the work will be disseminated to the public and stakeholders via museum lectures, and will complement ongoing efforts to develop hands-on research experiences for high school students. Paleoclimatic research can clarify the future behavior of regional climates by studying the past. This project exemplifies this goal by using new data from the mid-Pliocene Warm Period, specifically the mid-Piacenzian, to understand the response of North American Southwest rainfall to elevated greenhouse gases. This project tests the hypothesis that the spatial footprint of summer rainfall was much more extensive in the Pliocene. The research will reconstruct Plio-Pleistocene rainfall seasonality from marine sediment cores along the California margin and Baja California. Measurements of stable isotopes in leaf waxes will explicitly resolve changes in the balance of summer vs. winter rainfall. Complementary measurements of ocean surface temperature from organic proxies like alkenones will provide additional, independent constraints on regional environmental change. The project will also conduct a suite of Earth system model simulations to explore how changes in atmospheric parameterizations and model configuration influence simulated patterns of Pliocene rainfall. Proxy data and model simulations will be interpreted synergistically, with models helping inform proxy interpretations, and proxies helping to assess model skill. The research meets two major goals: first, it provides novel constraints on the Plio-Pleistocene evolution of key regional rainfall regimes like the North American Monsoon (NAM). Second, the project will help clarify the factors that influence model skill at simulating Pliocene hydroclimate, with broad implications for our understanding of the model configurations that most reliably predict regional responses to elevated CO2.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.

近年来，北美西南部的严重干旱引起了人们对了解该脆弱地区氢化气候的未来轨迹的强烈兴趣。研究过去的温室气候可以帮助确定可能导致西南降雨变化的过程。一个这样的间隔，即中新世的温暖时期，发生在330万年前，具有类似于近距离价值的二氧化碳浓度，这是一个有趣的难题。上新世的模拟表明，西南地区的广泛干燥条件，就像模型预测到21世纪末的西南大部分地区干燥一样。然而，多种地质证据表明上新世的湿条件较湿。该研究项目旨在通过最先进的，高分辨率的气候模型模拟和西南降雨的新重建来解决这种明显的悖论。这些重建将对北美季风等地区气候特征的上新世历史提供一些最初的约束。这些数据和模型模拟将用于评估上新世模型模拟中的偏差来源，并了解过去气候变化的过去间隔可能与当前的变暖有所不同。该项目直接应用于改善温暖世界中西南降雨的预测。这项工作的结果将通过博物馆的讲座传播给公众和利益相关者，并将补充为高中生开发动手研究经验的持续努力。古气候研究可以通过研究过去来阐明区域气候的未来行为。该项目通过使用新世中期温暖时期（特别是中期苯二）的新数据来体现这一目标，以了解北美西南降雨对升高温室气体的反应。该项目检验了以下假设：夏季降雨的空间足迹在上新世上更为广泛。这项研究将从加利福尼亚保证金和加利福尼亚州巴哈沿线的海洋沉积物核心重建Plio pel-Pleistecene降雨季节性。叶蜡中稳定同位素的测量将明确解决夏季平衡与冬季降雨的变化。诸如烯烃等有机代理的海面温度的互补测量将对区域环境变化提供额外的独立限制。该项目还将进行一套地球系统模型模拟，以探讨大气参数化的变化和模型配置如何影响上新世降雨的模拟模式。代理数据和模型模拟将通过有助于代理解释的模型进行协同解释，并有助于评估模型技能。该研究实现了两个主要目标：首先，它对北美季风（NAM）等关键区域降雨制度的普遍进化提供了新的限制。其次，该项目将有助于阐明影响模型技能模拟上新世氢化气候的因素，这对我们对模型配置的理解具有广泛的影响，这些奖项最可靠地预测了区域性的响应对提升的CO2。该奖项反映了NSF的法定任务，并通过评估该基金会的知识绩效和广泛的影响来评估NSF的法定任务。

项目成果

Evaluation of Arctic warming in mid-Pliocene climate simulations

• DOI: 10.5194/cp-16-2325-2020
• 发表时间: 2020-11-23
• 期刊: CLIMATE OF THE PAST
• 影响因子: 4.3
• 作者: de Nooijer, Wesley;Zhang, Qiong;Brierley, Chris M.
• 通讯作者: Brierley, Chris M.

Drier tropical and subtropical Southern Hemisphere in the mid-Pliocene Warm Period

• DOI: 10.1038/s41598-020-68884-5
• 发表时间: 2020-08
• 期刊: Scientific Reports
• 影响因子: 4.6
• 作者: G. Pontes;I. Wainer;A. Taschetto;Alexander Sen Gupta;A. Abe‐Ouchi;E. Brady;W. Chan;D. Chandan;C. Contoux;R. Feng;S. Hunter;Yoichi Kame;G. Lohmann;B. Otto‐Bliesner;W. Peltier;C. Stepanek;J. Tindall;N. Tan;Qiong Zhang;Zhongshi Zhang;Zhongshi Zhang;Zhongshi Zhang

Mid-Pliocene mesic subtropical hydroclimate over continents driven by land surface changes

地表变化驱动的上新世中期大陆副热带水文气候

• 发表时间: 2021
• 期刊: EGU General Assembly 2021
• 作者: Ran Feng, Tripti Bhattacharya

The Pliocene Model Intercomparison Project Phase 2: large-scale climate features and climate sensitivity

• DOI: 10.5194/cp-16-2095-2020
• 发表时间: 2020-11-04
• 期刊: CLIMATE OF THE PAST
• 影响因子: 4.3
• 作者: Haywood, Alan M.;Tindall, Julia C.;Lunt, Daniel J.
• 通讯作者: Lunt, Daniel J.

Expansion and Intensification of the North American Monsoon During the Pliocene

• DOI: 10.1029/2022av000757
• 发表时间: 2022-11
• 期刊: AGU Advances
• 影响因子: 8.4
• 作者: Tripti Bhattacharya;R. Feng;J. Tierney;Claire B. Rubbelke;N. Burls;Scott Knapp;M. Fu