Lisa C. Sloan
General Research Description
Paleoclimatology, Climate Change, and Earth System Science
The focus of my research is understanding the processes that have controlled past climates and environments, and understanding the processes that may control future climates and environments. As a geologist and paleoclimate modeler by training, my work on past climates includes consideration of all aspects of the rock record that can contribute information about the interacting systems of the lithosphere, atmosphere, oceans, cryosphere, and biosphere. For work on future climates we focus more on current processes and relationships, and also consider what we have learned from these systems in the past. For investigations of both past and future climates and environments we rely on complex models of climate and earth surface processes, as well as a variety of observations.
My work has concentrated primarily on deciphering Cenozoic climatic events and processes, with a major emphasis on warm and transitional intervals of that era of Earth history. However, with each advance that we make in understanding past climates, many new questions arise, about both past climates and possible future climates. As a consequence, my work in the past few years has expanded in scope to include not only the early Cenozoic, but also several projects that explore climate and environmental change in the recent past (the Holocene), the latest Cretaceous, and the next century. While these projects may seem unrelated at first glance, they are all related by the dynamics and feedbacks inherent in climate and environmental change across a range of space and time. Examples of work from these topics are summarized below.
The first theme of my research is that of warm and transitional climate intervals in Earth history. The intervals that we are investigating include the abrupt and extreme warming that took place at the end of the Paleocene (the Paleocene/Eocene Thermal Maximum, PETM), the warm but variable climate of the early Eocene, the cooling climate of the later Eocene and Oligocene, and the climatic consequences of a bolide impact at the end of the Cretaceous. We are exploring all of these topics using a variety of global climate models as well as many types of paleoclimate data. The PETM is an extremely exciting event in Earth history, one that saw a massive input of carbon into the atmospheric and oceanic system on timescales of possibly thousands of years. There is much to be learned about the events of the PETM, and we are working to model the climatic processes and events, in collaboration with data collected by J. Zachos at UCSC, T. Bralower at UNC-Chapel Hill, and now with a host of colleagues via a recent NSF Biocomplexity grant. This work will produce exciting new knowledge about the PETM event and about climate and geochemical cycles in the years to come. On the topic of Eocene climates, we are investigating the roles of atmospheric carbon dioxide and methane, the roles of Milankovitch forcing, and the role of the oceans and biosphere to explain the nature of the warm Paleogene world. In a new study we are also examining the role of the Arctic Ocean in contributing to the nature of warm climates of the early Cenozoic. All of these projects are helping to advance our knowledge about the dynamics and sensitivities of warm climate worlds. A new NASA-sponsored project with E. Pierazzo and A. Hahmann at U. Arizona will allow us to take a multi-model approach to investigating the climatic consequences of the bolide impact at the end of the Cretaceous. Our innovative approach should yield new insights into possible conditions at and after this event.
The second theme of my research, one that often overlaps with the first theme, is focused upon the nature of regional climates, environments, and processes. Some geologic (paleoclimatic) processes and questions are best addressed at regional, rather than global, scales. This is also true for modern and near-future questions in many cases. Pursuing the answers to these questions requires the application of regional climate models, as well as other types of models and observations. In the regional paleoclimate realm we are investigating the role of climate and land surface interactions to help explain the nature of early Cenozoic climates and climate changes in both western North America and in southern Australia. In the area of current and future climate change we have investigated the role of changing lake conditions in regional climate change in the Aral Sea region, and we now are exploring possible future climate scenarios and their potential impacts for the California region. Given California’s dependence upon water resources, this topic is an exciting and potentially important contribution to our knowledge of future climate change.