Collaborative Research: Central tropical Pacific climate variability over the Last Millennium

合作研究：过去千年中部热带太平洋气候变化

• 批准号: 2103059
• 负责人: Kim Cobb
• 金额: $ 59.33万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103059&HistoricalAwards=false
• 关键词: Collaborative; Research; Central; tropical; Pacific

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The project will assemble radiocarbon-dated segments of ancient coral recovered from islands in the central equatorial Pacific to study climate conditions during the last 1000 years. It will focus on two important time periods, the Medieval Climate Anomaly (850-1300 ago) and the Little Ice Age (1400-1850) to look at what factors cause El Nino conditions. Researchers will reconstruct monthly-resolution records of seawater temperature and salinity conditions by targeting growth bands in coral skeletons. This project supports research training educational opportunities for several undergraduate and graduate students. It also supports a research collaboration among two early career scientists and others who have a strong track record of participation in K-16 education and public outreach with an emphasis on broadening diversity and inclusion of underrepresented communities. These efforts will continue with guest lectures at a nearby minority-serving institution and by offering summer research opportunities for local high school students.Improving the accuracy of future climate projections requires a more complete understanding of internal vs. externally forced changes in tropical Pacific climate on a broad range of timescales. Coral-based paleoclimate records have dramatically improved our understanding of interannual climate variability in the tropical Pacific, however, similar insights into centennial-scale variability have thus far remained unattainable due to (i) diagenesis, which can significantly bias coral reconstructions, and (ii) colony-to- colony offsets in coral proxies, which introduce large uncertainties in estimates of mean climate change from single corals. Informed by two decades of work at Kiritimati Island (2degN, 157degW), this project will generate ~50 new well-dated and multi-proxy records of climate variability across the last millennium. Using a novel approach that layers paired coral oxygen isotope and Sr/Ca measurements, with a new paleothermometer, Sr-U, this reconstruction will provide the first set of robust, quantitative, and independent estimates of central tropical Pacific surface temperature (SST) and hydroclimate trends across the Medieval Climate Anomaly (MCA; 900-1200CE) and Little Ice Age (LIA; 1500-1800CE). The fidelity of these fossil coral records will be further ensured using rigorous screening for diagenesis and a microscale analyses to extract reliable climate information from altered corals. Comparisons of these new reconstructions with transient climate simulations will provide much-needed context for present-day trends and allow us to investigate the tropical Pacific’s long-term response to external forcings and climate feedbacks. Broader impacts to this project include a dramatic improvement to our understanding of natural climate variability in the tropical Pacific, allowing for the better quantification of regional anthropogenic climate trends, and the improvement of future climate projections by providing more accurate benchmarks for climate models. As climate change continues to dominate social consciousness, the PI will actively engage in public outreach efforts to communicate the results of the paleoclimate research as well as more general information about local/regional impacts of future climate change. It supports research training and mentoring of several graduate students and summer research experiences for high school students from a nearby school district which has a 90% underrepresented minority student population.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.

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。该项目将收集从赤道太平洋中部岛屿上发现的古珊瑚的放射性碳测年片段，以研究过去1000年的气候条件。它将聚焦于两个重要的时间段，中世纪气候异常(850-1300年前)和小冰期(1400-1850年)，看看是什么因素导致了厄尔尼诺现象。研究人员将通过瞄准珊瑚骨骼中的生长带来重建海水温度和盐度条件的月度分辨率记录。该项目支持为几名本科生和研究生提供研究培训教育机会。它还支持两名早期职业科学家和其他在参与K-16教育和公众宣传方面有良好记录的人之间的研究合作，重点是扩大多样性和纳入代表性不足的社区。这些努力将继续，在附近的少数族裔服务机构进行客座讲座，并为当地高中生提供暑期研究机会。要提高未来气候预测的准确性，需要更全面地了解热带太平洋气候在广泛时间范围内的内部和外部强迫变化。基于珊瑚的古气候记录极大地改进了我们对热带太平洋年际气候变异性的理解，然而，由于(1)成岩作用，这可能严重偏离珊瑚重建，以及(2)珊瑚替代物中群落间的偏移，这给从单一珊瑚估计平均气候变化带来很大的不确定性，迄今还无法对百年尺度的变异性进行类似的深入了解。在基里蒂马蒂岛(北纬2度，西经157度)进行了20年的工作，该项目将产生近50项关于上个千年气候变化的新的、准确的和多指标记录。使用一种新的方法，将珊瑚氧同位素和锶/钙测量与新的古温度计锶-U配对，这种重建将提供第一套稳健的、定量的和独立的估计热带太平洋中部表面温度(SST)和跨越中世纪气候异常(MCA；900-1200CE)和小冰期(LIA；1500-1800CE)的水文气候趋势。这些化石珊瑚记录的保真度将通过对成岩作用的严格筛选和从蚀变珊瑚中提取可靠气候信息的微尺度分析来进一步确保。将这些新的重建与瞬变气候模拟进行比较，将为当今的趋势提供急需的背景，并使我们能够调查热带太平洋对外部强迫和气候反馈的长期反应。对该项目的更广泛影响包括显著提高我们对热带太平洋自然气候变异性的了解，使我们能够更好地量化区域人为气候趋势，并通过为气候模型提供更准确的基准来改进未来的气候预测。随着气候变化继续在社会意识中占据主导地位，国际气候倡议将积极开展公众宣传工作，以传播古气候研究的结果以及关于未来气候变化对当地/区域影响的更一般信息。它支持对几名研究生的研究培训和指导，以及为来自附近学区的高中生的暑期研究经验，该学区有90%的少数民族学生未被充分代表。该奖项反映了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。