Collaborative Research: P4Climate--Testing Hypotheses of Mesoamerican Hydroclimate over the Last Several Glacial Cycles

合作研究：P4Climate——检验最后几个冰川周期中美洲水气候的假设

• 批准号: 2303488
• 负责人: Yemane Asmerom
• 金额: $ 14.88万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303488&HistoricalAwards=false
• 关键词: Collaborative; Research; P4Climate; Testing; Hypotheses

This project seeks to test climate forcing hypotheses for past regional climate in the Mesoamerican monsoon that include sea surface temperature, ocean circulation, Heinrich event forcing, and other glacial-interglacial boundary condition data against stalagmite delta Oxygen-18 from southwestern Mexico spanning several glacial cycles. New proof-of-concept stalagmites from JX Cave, Mexico, cover a time period from approximately 53,000 to 105,000 years before present (BP), and a new sample from Sistema Huatla, Mexico spans 115,000 to 340,000 years BP. The preliminary data from these samples departs from a smooth sinusoidal orbital insolation hypothesis, and instead shows abrupt threshold-like behavior including monsoon collapses apparently coincident with Heinrich events in the North Atlantic, notably during the relatively warm interval of Marine Isotope Stage (MIS) 5b. The research will focus on weak monsoon intervals during non-glacial warm periods such as MIS 5, 7, and 9, because these times may represent paleo-analogs of future aridity associated with the projected weakening of ocean circulation due to anthropogenic climate change.Why this research and why now? The prevailing orbital monsoon hypothesis describes a strong and positively coupled relationship between summer incoming solar radiation (insolation) on orbital precession (21,000 year) timescales and regional monsoon strength. Long monsoon paleoclimate records are revealed in the inverse correlation between regional scale monsoon strength and speleothem oxygen isotope values. The orbital control on monsoons is strongly expressed in the East Asian and South American monsoon systems where speleothem oxygen isotope time series show smooth sinusoidal variations that are paced by orbital insolation. However, in other tropical areas the orbital insolation hypothesis fails to explain hydroclimate variations, notably in Central America, where speleothem oxygen isotope does not correlate to summer insolation. This disconnect suggests that paleoclimate variations in southern Mexico and Central America (Mesoamerica) may be explained by the orbital monsoon hypothesis.The potential Broader Impacts (B.I.) include supporting a graduate student training and engaging students from historical underrepresented groups students in Nevada and also at Fort Valley State University, an Historical Black College and University (HBCU) in Georgia. In addition, the researchers will involve the indigenous Mazatec community in Plan Carlota near Sistema Huatla in cave science research as well as the development of cave education posters in Spanish and Mazateco.Direct potential scientific benefits to society from this project include an improved understanding of tropical hydro climate variability in a region which is very vulnerable to climate change. The results of this research may also help to inform policy makers about the amplitude and timing of abrupt events in the past and the potential of similar events in the future.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.

该项目旨在测试中美洲季风过去区域气候的气候强迫假设，包括海面温度、海洋环流、海因里希事件强迫和其他冰期-间冰期边界条件数据，针对来自墨西哥西南部跨越几个冰川周期的石笋三角洲Oxygen-18 。来自墨西哥 JX Cave 的新概念验证石笋涵盖了距今约 53,000 至 105,000 年 (BP) 的时期，而来自墨西哥 Sistema Huatla 的新样本则涵盖了距今 115,000 至 340,000 年的时期。这些样本的初步数据偏离了平滑的正弦轨道日射假设，而是显示了突然的阈值行为，包括季风崩溃，显然与北大西洋的海因里希事件一致，特别是在海洋同位素阶段（MIS）5b相对温暖的时期。 该研究将重点关注非冰川温暖期（例如 MIS 5、7 和 9）期间的弱季风间隔，因为这些时间可能代表未来干旱的古类似物，该干旱与预计由于人为气候变化而导致的海洋环流减弱有关。这项研究为何是现在？盛行的轨道季风假说描述了轨道岁差（21,000 年）时间尺度上夏季入射太阳辐射（日照）与区域季风强度之间的强正耦合关系。区域尺度季风强度与洞穴氧同位素值之间的负相关揭示了长期季风古气候记录。轨道对季风的控制在东亚和南美季风系统中得到强烈体现，其中洞穴氧同位素时间序列显示出由轨道日照调节的平滑正弦变化。 然而，在其他热带地区，轨道日照假说无法解释水文气候变化，特别是在中美洲，那里的洞穴氧同位素与夏季日照无关。 这种脱节表明，墨西哥南部和中美洲（中美洲）的古气候变化可以用轨道季风假说来解释。潜在的更广泛影响（B.I.）包括支持研究生培训和吸引来自内华达州和美国的历史上代表性不足群体的学生。谷堡州立大学是佐治亚州的一所历史悠久的黑人学院和大学 (HBCU)。此外，研究人员还将让 Sistema Huatla 附近 Plan Carlota 的土著 Mazatec 社区参与洞穴科学研究，以及制作西班牙语和 Mazateco 语言的洞穴教育海报。该项目对社会的直接潜在科学效益包括加深对热带地区的了解。非常容易受到气候变化影响的地区的水文气候变化。这项研究的结果还可能有助于让政策制定者了解过去突发事件的幅度和时间以及未来类似事件的可能性。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。