A one-million record of orbital-scale changes in temperature and precipitation from the Indo-Pacific Warm Pool

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Tropical climate is changing rapidly – rainfall events are becoming more intense, and droughts more severe. These changes affect the affect the lives of billions of people who rely on rainfall for their livelihoods, and have important implications for the world due to connections between tropical and global climates. Predicting how rainfall and temperature will change in the future requires long records to test climate models and theory. Such records are generally scarce in the tropics, and particularly in the tropical western Pacific, where existing records disagree substantially on the pattern and magnitude of past changes in climate. The goal of this project is to develop new records of temperature, rainfall, and vegetation from the tropical western Pacific, a region that is especially important to global climate processes, and to investigate their causes. This research will enable us to test theories of tropical and global climate change, and thereby to improve the prediction of future climates in this region. The project will provide for many opportunities for US graduate and undergraduate students to conduct research and will develop new classroom modules on climate change to be used in the Providence Public School System.This research will investigate orbital-scale variations in rainfall, temperature, and vegetation during the past 1.1 million years in the Indo-Pacific Warm Pool (IPWP) through analysis of recently-recovered sediment drill cores from Lake Towuti, located on Sulawesi Island in central Indonesia. Through organic geochemical analyses of these sediments, the project will evaluate the impacts of changes in tropical seasonal insolation, high-latitude ice volume, temperature, and atmospheric greenhouse gas concentrations, and sea level on IPWP climate across critical transitions in global climate boundary conditions. The research will focus on global climate transitions during the Mid-Pleistocene, 800,000 years ago, when glacial-interglacial variability transitioned from predominantly 41-kyr to 100-kyr ice-age cycles, and 430,000, when the 100-kyr cycles intensified. The results are expected to contribute to understanding how tropical climates change in response to climate boundary conditions that differ from the present day.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.