Global ocean circulation during the late Quaternary: Paleoceanographic constraints from the Western Equatorial Pacific

The ocean initiates, amplifies and mediates global climate change on time scales ranging from less than a year to thousands of years. The overarching long-term goal of my research program is to characterize and quantify large-scale ocean circulation both in the modern and past ocean. Large-scale ocean circulation plays a pivotal role in global climate, for example through the redistribution of heat and its control on the partitioning of carbon dioxide, CO2, between the ocean and atmosphere. My research will, therefore, provide uniquely important observational constraints on rates and amplitudes of climate change. Specifically, I seek to characterize the dynamic relationship between the cross-hemispheric and inter-basin ocean exchanges in the Western Equatorial Pacific during the late Quaternary (the last 150,000 years). The Western Equatorial Pacific is the world's only "water mass crossroad", where surface waters flowing from the Pacific to the Indian Ocean through the Indonesian Throughflow are overriding deeper waters flowing from the southern to the northern hemispheres. My research of this pivotal - but much understudied - region of the world's ocean will address critical gaps in our understanding, with a particular focus on three interlinked short-term objectives: 1) How did the Indonesian Throughflow vary in the past? 2) What is the effect of changing water mass sources on the nutrient conditions along the vast equatorial Pacific? 3) How did the circulation of Antarctic-sourced intermediate and deep waters change during the last glacial-interglacial cycle? The primary focus of the overall research program will be on four time intervals, which together constrain the full dynamic range of ocean and climate change during the late Quaternary: a) the last 2,000 years, to contextualize ongoing and projected global climate change; b) the early Holocene insolation maximum (9,000 - 6,000 years ago), to assess the effect of regional climate on the Indonesian Throughflow compared the last 2,000 years; c) the last glacial-interglacial transition (25,000 - 10,000 years ago), to establish rates and amplitudes of change during the last natural global warming event; and d) the last interglacial period (125,000 - 115,00 years ago), to compare to the present interglacial. Understanding past ocean and climate variability is key to understanding the present-day ocean-climate system and for modelling future global climate change in the Anthropocene. My research program will continue to contribute critically needed quantitative constraints on past ocean and climate change. The research program will also provide advanced education and training in cutting-edge, high-quality research, which will ensure future research careers and employment of my students in impactful positions related to natural science.