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

渐新世以来的陆地有机物 (TOTO)：非洲的降雨如今，近 1 亿人依赖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。非洲还拥有丰富的人类进化历史，包括早期人类化石遗址、多次走出非洲的证据以及最早的石器创新。尽管该地区对于了解气候变化和人类进化非常重要，但长期以来人们对热带非洲缺乏了解。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（该生态系统自东向西穿过撒哈拉沙漠以南的非洲），并量化地球轨道自然循环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。研究人员将召开新的非洲气候会议，以促进知识共享、网络活动和拉蒙特实验室参观，通过形成深入、持久的合作，直接对抗非洲研究人员被西方科学排斥的长期历史。热带地区占地球表面的一半，作为全球水文泵，并包含世界上最大的潜在甲烷来源，但对新生代热带气候的数据和了解都缺乏。特别是热带非洲，尽管它对于理解人类进化、热带水文气候和陆地生态系统对气候变化的反应很重要，但在历史上一直没有得到充分研究。对未来气候情景的预测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。研究人员将使用海洋沉积物核心中保存的生物标记来生成新的长期高分辨率降水、植被和火灾重建，这些生物标记捕获了过去 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随时间变化的幅度、周期性、平均值和关系，以破译研究窗口中变异幅度的差异，从而表征各种边界条件下的敏感性。该项目将为我们最早祖先的进化提供重要的环境背景，并将为这个高度敏感地区的未来陆地对全球变暖的反应模型提供信息。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.