Introduction to Day 2

Linda O. Mearns — National Center for Atmospheric Research

Session 7: Paleoclimatology

Morning Session Moderator: Kristie Ebi — Stanford University

John Kutzbach — University of Wisconsin

I review Steve Schneider's contributions to the study of paleoclimate including his pioneering collaborative work in developing early Earth System Models, in studying the response of climate to volcanic eruptions, in using models to examine the sensitivity of paleoclimates to changes in external forcing, in examining climate/ecology linkages, and in showing how studies of paleoclimate help inform studies of future climates. I then present examples of the evolution of paleoclimatic studies over the period of Steve's professional career – an evolution made possible by improved observations (more variables, more spatial coverage, improved dating), improved earth system models, and the growth in computer resources. I close with brief examples of future directions of paleoclimate studies.

Carolyn Snyder — Delaware Dept. of Natural Resources and Environmental Control

I discuss several key themes from Steve Schneider's contributions to paleoclimate research. First, Steve led trail-blazing collaborations of climate modelers and earth scientists throughout his career. He demonstrated the need for a hierarchy of model complexity and was able to integrate climate models and data at different scales of time, space, and complexity. Second, Steve interpreted the Earth System using complex system science and showed that "systems thinking" is critical for climate research. He contributed insights to the fundamental behavior of the Earth System through his work on the coevolution of climate and life, the pacemaker of the glacial-interglacial cycles, and the Gaia hypothesis. He investigated the nonlinearities and abrupt changes in the Earth System's dynamics, focusing on the risks associated with abrupt ocean circulation changes, the path dependence of vegetation change, and the nonlinear impacts on species. Third, Steve demonstrated the importance of rigorous uncertainty analysis and the use of a risk assessment framework for making paleoclimate discoveries relevant and useful to decision-makers. Through structured probabilistic analysis, Steve was able to transparently communicate what is currently known about past climate dynamics and about the potential for future risks, including low-probability, high-impact events or "imaginable surprises." As an example, I discuss Steve's work on climate sensitivity. I conclude with reflections on future advancements in paleoclimate research.

Session 8: The economics of climate change

Larry Goulder — Stanford

This presentation is meant to serve both as a tribute to Steve and as a demonstration of how economic analysis can inform climate change policy. Here I'll illustrate some joint work that Steve and I conducted to assess alternative policy options for stimulating the invention of clean technologies. I'll go on to describe some very recent work and findings by other authors – analyses that might have been stimulated by our joint efforts.

We cannot understand climate change causes, consequences or responses without the social sciences. Steve understood this when he admitted me to NCAR's advanced study program in the 1970s - a geography student with interests in human responses to hazards – and when he encouraged me to take on the challenge of modeling how climate change and variability might affect food security. He was an early champion of integrating natural and social science approaches to climate change as, for example, a member of the Social Science Research Council Committee for Research on Global Environmental Change and as the editor of Climatic Change which published a number of social science articles in its first year (1977). In my paper I will discuss the role of the social sciences in climate change research by reviewing key arguments about the importance and challenges of understanding vulnerability, socioeconomic scenarios, human perceptions/behaviors and climate governance. I will also flag some enduring myths and misunderstandings about the social sciences including those about the human causes of environmental change, the importance of the physical environment and environmental information, the effectiveness of different policy responses, and the role of social scientists in interdisciplinary climate research.

Kirstin Dow — University of South Carolina

Understanding climate changes, anticipating the potential consequences, and evaluating possible responses requires interdisciplinary science and engagement with broad conversations taking place outside academia. Steve Schneider was a leader in helping scientists of all backgrounds to engage the challenges of interdisciplinary research and effectivelycommunicate that research and its uncertainties to diverse audiences. His efforts were critical to building the foundation we have for addressing the work ahead. In this paper, I will focus on social sciences insights into understanding risks, uncertainties, and societal response. The discussion will address social science contributions to other societal debates over risks and uncertainty and consider the challenges in bringing these insights fully to bear in the context of climate change. As understanding of climate processes improves, there is growing potential and pressure to more fully explore potential impacts, to understand the relationship between climate changes, thresholds, and well-being, and to inform the design of response strategies. Advancing knowledge and capacity in social sciences is essential to continuing to integrate sciences and developing approaches to characterize and communicate knowledge and uncertainty of those integrations. Social sciences will also play a major role in advancing our ability to provide decision relevant science for adaptation and mitigation interactions and priorities.

Uncertainty, or more generally, debate about the level of certainty required to reach a "firm" conclusion, is a perennial issue in science. In "science for policy" in the global change arena, the challenges are particularly acute because of scientific complexity, long time horizons, and large political and economic stakes, among other factors. Moss and Schneider prepared uncertainty guidelines for the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) that recommended a process to make expert judgments of levels of confidence and uncertainty more systematic, and provided calibrated textual qualifiers to improve communication of findings to users. In spite of the guidance and efforts to disseminate it, each of the three IPCC working groups approached the issue differently in the TAR, and a number of "medium confidence" findings were reported with qualifiers such as "could" or "some" that made those conclusions essentially meaningless. So what did the guidance achieve? This presentation will review the recommendations, immediate results in the TAR, the evolution of uncertainty guidance in subsequent IPCC assessments, and ensuing debates that emerged in research on climate change, decision analysis, and risk communication. It will highlight emerging challenges in providing science for decision making in the era of increasing model resolution/complexity and burgeoning interest in adaptation at regional and finer scales.

Jean-Pascal van Ypersele — Université catholique de Louvain, Belgium

Uncertainty surrounds some aspects of climate issues, and Steve Schneider was a master at explaining its significance in a scientific perspective as well as in terms of policy. As Richard Moss explained, the IPCC guidance on the handling and communication of uncertainties owes a lot to Steve Schneider. In this talk, I will evoke some other aspects of the challenge of taking climate decisions under uncertainty, building on Steve's insights at every opportunity. One of the purposes of science is to reduce uncertainties, and climate scientists have succeeded bounding uncertainties in many areas, which I will briefly review. We know a lot already. But the remaining uncertainties are still used by some as an excuse for not acting, despite the precautionary principle which says that uncertainty should not prevent action when there is a risk of grave or irreversible consequences. Actually, most human decisions are taken in a context of uncertainty. In economic, military, social, or human relations decisions, one has to act every day without certainty. Why should it be different for climate? Would it be easier to take climate mitigation or adaptation decisions, at home or under UNFCCC if scientific uncertainties had been eliminated? A thought experiment suggests this would certainly(!) not always be the case. The differing values, interests, and priorities would still be present. And Naomi Oreskes' merchants of doubt would continue to mislead. And the uncertainties related to human decisions would remain. So, we are stuck with uncertainties in the climate world. As we cannot afford to lose the "planetary gamble" Steve discussed in "Laboratory Earth", it will remain extremely important for scientists and the IPCC to understand, qualify, and communicate uncertainties in the best way, so that good decisions can be taken. The work and life of Steve Schneider will continue to inspire this for a long time. As Steve's family said: "Now it's up to us".

Session 11: Strategies for improving climate science communication

Naomi Oreskes — UC San Diego

Naomi Oreskes, Keynyn Brysse, Jessica O'Reilly and Michael Oppenheimer Numerous polls, studies, and daily life attest to the doubt, dismissal, and even outright denial of the scientific evidence of anthropogenic climate change. In previous work, one of us (NO) has examined sources of doubt and confusion external to the scientific community: doubt- mongering campaigns organized by think-tanks, and motivated by the intertwined political ideologies of libertarianism, neo-liberalism and free-market fundamentalism. Here, we turn to the question of how scientific communication may have contributed to public confusion, particularly the scientific tendency to downplay dramatic results. We call this tendency ESLD— Erring on the Side of Least Drama—a tendency that we suggest arises from the scientific virtues of skepticism, dispassion, and restraint, but which has perhaps inadvertently led scientists to under-estimate the tempo, mode, and severity of climate change, and given the public the impression that the scientific findings are less secure, and their implications less alarming, than they actually are.

Most people now take weather forecasting for granted as an imperfect but largely reliable source of knowledge. By contrast, climate knowledge — not only model predictions, but also historical climate data — obstinately fails to recede noiselessly into the background. Instead, climate controversies constantly seem to lead down into the guts of the climate knowledge infrastructure, inverting it, regenerating debates about the quality of historical data and simulation models. This talk, from a historian of science and technology, will argue that beyond disinformation and the (very real) "war on science," these debates regenerate for a more fundamental reason. The climate knowledge infrastructure never disappears from view because the black box of climate history is never closed. Scientists are always opening it up again, studying the origins of data to find out more about how old numbers were made and revising their data accordingly. New metadata breed new data models; those in turn breed new pictures of the past. From the point of view of scientists, these changes improve the quality of knowledge, but to an outsider they can readily appear arbitrary. I will conclude with some reflections on how the changing information environment (blogs, open access to data and models, citizen science, etc.) may affect the future of climate science. Throughout, I will argue that the language of uncertainty has served the scientific community poorly in public communication.

Stephen H. Schneider Award For Outstanding Climate Science Communication

One of Steve's great passions was the exploration of the complexities of the coupled human- natural systems of our planet. He devoted tremendous effort to the characterization of the uncertainties inherent in this scientific understanding in ways that enable communication of the state of knowledge. Such characterization, both of what is well established and where uncertainties remain, is essential for informing policy decisions. Steve imparted this passion for learning and communicating to the next generation of scientists, including myself, a student and collaborator with Steve for many years. I will discuss some of Steve's methods, with a specific focus on his role in the development of the first and subsequent guidance documents on the treatment of uncertainties in IPCC assessment reports. I will also present the elements of the recently developed guidance for the upcoming IPCC Fifth Assessment Report, and its linkages to the foundation built by Steve.

A number of universities have established training programs in climate science, and a key feature of almost all these programs in an emphasis on interdisciplinary thinking. This focus on interdisciplinarity was a hallmark of Steve's work in climate science, and something that he often spoke about. In this talk, I will discuss such lessons in climate science education that I learned from Steve as his graduate student at Stanford University. I will also discuss how those lessons have influenced the ways that I and others train their students in climate science.

Federal funding agencies and students themselves are increasingly committed to bringing scientific knowledge to real-world applications. Graduate training has been transformed by the NSF-IGERT and other emerging interdisciplinary programs that call for students to pursue multidisciplinary research and form interdisciplinary collaborations. This vision of researchers who can move across fields in search of workable solutions was one of Steve's dreams, a dream increasingly realized at Stanford and implemented by his former students worldwide. As an example of recent progress in interdisciplinary training, I will present the University of Notre Dame's IGERT program, Global Linkages in Biology, Environment, and Society and give examples of how interdisciplinary thinking is increasingly important in climate science, broadly defined. As a case study, I will argue that climate change biology is growing from a science that diagnoses ecological impacts of climate change to a predictive science that informs decision- making and enables humans to intervene and help ecosystems adapt to changing climatic conditions.