Collaborative Research: Sources and circulation of intermediate and deep waters and their role in Campanian-Maastrichtian global cooling

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The late Cretaceous period (83-66 Ma) saw an important climatic transition from the extreme warmth of the early Late Cretaceous to the cooler conditions of the Early Paleocene. Evidence from multiple ocean basins indicates that this transition was accompanied by major changes in ocean circulation. However, the nature of these oceanographic changes and their role in global cooling are the subject of debate. Some interpretations call for expansion of southern component water (SCW) through the global ocean, possibly causing widespread cooling through low-latitude upwelling of cold deep waters. Others suggest shifts in the dominance of regional sources of deep-water formation, including initiation of North Atlantic sources, leading to changes in intra-basinal heat transport and climate. This collaborative research, involving scientists from the University of Missouri-Columbia, the University of Florida, and the University of Michigan, seeks to resolve these controversies. Building on their earlier findings, the researchers will generate new geochemical proxy data from locations that will, in combination with existing data, constrain possible intermediate- and deep ocean sources and circulation modes. They will also evaluate the plausibility of paleoceanographic interpretations through climate model simulations, testing hypotheses regarding the effect of gateways and greenhouse gas concentrations on circulation patterns and deep convection and their links with global climate change. The results of this work will add to our knowledge about the relationship between ocean circulation and global climate change and, in this way, contribute to efforts to predict future climate change. In addition, the researchers will conduct specific activities that contribute to general education and the dissemination of scientific understanding, and the training and mentoring of young scientists including the following: (i) developing short videos to communicate the excitement and novelty of paleoceanographic research to the public, to be featured in displays at natural history museums at the researchers? home institutions, and posted on popular websites, (ii) training graduate students at each of the participating institutions, and (iii) disseminating results through publications, presentations at professional meetings, and by integrating research into lecture material, discussions, and classroom exercises for graduate and undergraduate students.