Terrestrial Organics since The Oligocene (TOTO): The Rains Down in Africa

渐新世以来的陆生有机物：非洲的降雨今天，近1亿人依靠萨赫勒地区的土地为生，该地区对洪水、干旱和野火高度敏感，使粮食和其他资源面临风险。非洲也有丰富的人类进化史，包括早期的人类化石遗址、多次走出非洲的证据，以及最早的石器创新。尽管该地区对了解气候变化和人类进化具有重要意义，但人们对热带非洲缺乏长期的了解。为此，研究人员将生成西非过去2500万年的降雨、植被和火灾的新记录，以研究萨赫勒生态系统的变化，并量化地球轨道上自然循环的影响，以及全球和区域条件的长期变化对生态系统变化和人类进化的影响。萨赫勒生态系统位于撒哈拉沙漠以南，东西向横跨非洲。这组科学家将召开一个新的非洲气候会议，以促进在拉蒙特的知识共享、网络活动和实验室参观，通过形成深入、持久的合作，直接解决西方科学排斥非洲科学家的长期历史问题。热带地区占地球表面的一半，是全球水文泵，蕴藏着世界上最大的潜在甲烷来源，然而，关于新生代热带气候的数据和理解仍然缺乏。特别是热带非洲，尽管它对理解人类进化、热带水文气候和陆地生态系统对气候变化的响应具有重要意义，但历史上对它的研究一直不足。对未来气候情景的预估需要量化过去气候对轨道强迫和边界条件（即区域反照率、冰量、全球温度）的响应。研究人员将利用保存在海洋沉积物核心中的生物标志物，生成新的长期和高分辨率的降水、植被和火灾重建，这些生物标志物捕获了过去2500万年的热带西非气候。统计和时间序列分析将评估水文气候、生态系统和火灾代理之间的振幅、周期性、平均值和关系，以破译研究窗口内变异性振幅的差异，以表征不同边界条件下的敏感性。这个项目将为我们最早的祖先的进化提供关键的环境背景，并将为这个高度敏感地区未来陆地对全球变暖的反应模型提供信息。该奖项反映了美国国家科学基金会的法定使命，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。

Terrestrial Organics since The Oligocene (TOTO): The Rains Down in AfricaToday, nearly 100 million people depend on the lands in the Sahel region, which is highly sensitive to flooding, droughts, and wildfires, putting food and other resources at risk. Africa is also rich in human evolutionary history, including early human fossil sites, evidence for multiple dispersals out of Africa, and the earliest stone tool innovations. Despite the region’s importance for understanding climate change and human evolution, there is a lack of understanding of tropical Africa over long intervals. To that end, the investigators will generate new West African records of rain, vegetation, and fire over the last 25 million years to study changes in the Sahel ecosystem, which runs east-west across Africa south of the Sahara desert, and to quantify the effects of natural cycles in Earth’s orbit and long-term changes in global and regional conditions on ecosystem change and human evolution. The investigators will convene a new African Climate Conference to facilitate knowledge sharing, networking events, and laboratory tours at Lamont to directly combat the long history of the exclusion of African researchers in Western science by forming deep, lasting collaborations.The Tropics comprise half of Earth’s surface, serve as the global hydrological pump, and contain the world’s largest potential source of methane, yet there is a dearth of data and understanding of tropical climate over the Cenozoic. Tropical Africa, in particular, has been historically under-studied, despite its importance for understanding human evolution, tropical hydroclimate, and terrestrial ecosystem responses to climate change. Projections of future climate scenarios require quantification of past climatic responses to orbital forcings and boundary conditions (i.e., regional albedo, ice volume, global temperature). The investigators will generate new long-term and high-resolution precipitation, vegetation, and fire reconstructions using biomarkers preserved in a marine sediment core that capture the last 25 million years of tropical West African climate. Statistical and time series analyses will evaluate the amplitudes, periodicities, means, and relationships between hydroclimate, ecosystem, and fire proxies through time to decipher the differences in the amplitude of variability in the study windows to characterize sensitivity in the context of various boundary conditions. This project will provide crucial environmental context for the evolution of our earliest ancestors and will inform models of future terrestrial responses to global warming in this highly sensitive region.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.