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

Lead PI: Kevin Uno , Rachel Lupien

Unit Affiliation: Biology and Paleo Environment, Lamont-Doherty Earth Observatory (LDEO)

January 2022 - December 2024
Africa ; Sahel
Project Type: Research

DESCRIPTION: Today, 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.