Sedimentary Geology and the Future of Paleoclimate Studies

Recent community efforts have highlighted the importance of deep-time paleoclimatology to the understanding of Earth processes as a way of expanding our understanding of the vast range of states possible in the Earth System. Advances in our collective understanding of these “alternative-Earth” states shed light on forcings and feedbacks of the climate system, as well as responses of the biosphere, ultimately bringing more rigor and predictability to the study of current and future global change. Sedimentary geology and paleontology are squarely in the middle of these efforts. Geoscientists from both subdisciplines have posed the major questions that must be answered and have implemented an action plan to answer those questions. Furthermore, increasing resolution of time and parameters (climatic and biotic) enabled by technological advances are bringing new rigor to paleoclimate studies, extending our collective reach to strata dating to everdeeper reaches of geologic time. New advances will require, increasingly, the actions and coordination of large multidisciplinary teams galvanized around critical science questions, and armed with the latest proxies and geochronologic tools. INTRODUCTION In the March issue of The Sedimentary Record, Montañez and Isaacson (2013) outlined recent developments in which the sedimentary geology and paleontology communities have “loudly and clearly through various venues articulated a research agenda for the future” (Montañez and Isaacson, 2013, p. 8). These venues include NRC reports (National Research Council, 2011, 2012); a new, community-driven initiative, TRANSITIONS (Parrish et al., 2012); and a new NSF funding initiative, Earth-Life Transitions (NSF Program 12-608), which was based on TRANSITIONS and on recommendations in the National Research Council (2012) report that examined research opportunities in the Earth sciences. In this article, we would like to focus on the community’s research agenda for paleoclimate studies, and give a glimpse into the critical role of this research. CHALLENGES AND QUESTIONS The TRANSITIONS team (Parrish et al., 2012) reviewed more than 10 years of white papers and initiatives, which collectively illustrate that all parts of our very large and diverse community are and have been for many years united around a singular intellectual challenge: “Understanding the full range of Earth-life process behaviors through all of Earth history, including deep time, is vital for addressing urgent societal issues, and these processes must be addressed in a systematic and interdisciplinary fashion” (Parrish et al., 2012). The importance of paleoclimate studies is demonstrated by the four overarching questions identified in TRANSITIONS that must be answered in order to meet this challenge: 1. What is the full range of potential climate system states and transitions experienced on Earth? 2. What are the thresholds, feedbacks, and tipping points in the climate system, and how do they vary among different climate states? 3. What are the ranges of ecosystem response, modes of vulnerability, and resilience to change in different Earth-system states [including climate]? 4. How have climate, the oceans, the Earth’s sedimentary crust, carbon sinks and soils, and life itself evolved together, and what does this tell us about the future trajectory of the integrated Earth-life system? Deep time (before 2 Ma) records contain information about climate that must be understood in order to confidently model and predict future climates. The TRANSITIONS initiative specifically delineated deeptime climate as one of the key directions this research will take; others include landscapes, and biology and environments. Specifically with respect to the deep-time research direction, TRANSITIONS emphasized the following questions: 1. What is the full range of potential climate states and transitions on Earth? 2. What are the thresholds and feedbacks in Earth’s climate system? 3. What is the biotic response and resilience to changes in climate states? Answering these questions falls directly under the purview of sedimentary geology and paleontology communities. The deep-time sedimentary record is the repository of nearly all evidence of climate and environmental change, including, for example, previous abrupt climate-