ABSTRACT

Climate risks are now being taken into account in an ever-widening range of human activities. By a "climate risk" I mean the probability of some particular loss to human society or ecosystems from climate-related hazards. Risk is the product of hazard (the component related to climate; e.g., the probability of a given level of flooding, heat, wind, etc.), exposure (the assets at risk, which can include human or nonhuman lives), and vulnerability (the level of loss experienced for a given level of hazard). Each can be represented with different degrees of complexity, different balances of empiricism vs. first principles, and different spatial or temporal resolutions. These choices are made differently in different application areas, and it is often not clear why. What is gained or lost by doing one vs. another? How should the right approach depend on the specific problem being solved? Our confidence in our predictions and projections of global climate change derives in part from understanding of the climate system gained through hierarchies of models at different levels of complexity. Hierarchies of a sort do exist in climate risk modeling, in that different models have different degrees of complexity. But these hierarchies are neither consciously constructed nor well understood, as the different types of models are constructed and used by different communities. For example, insurance industry catastrophe models, which represent individual weather events in great detail, but have not until recently incorporated climate change in any serious way; while integrated assessment models, at least until recently, did not represent extreme events, nor many other consequential aspects of the climate system. I will argue that there is a great need for an explicit, open hierarchy of climate risk and impacts models (as exists in physical climate science), and that this presents a great intellectual opportunity. In short, we need an academic discipline of climate risk, including a theoretical dimension.

About the Speaker:

Adam Sobel is a professor at Columbia University's Lamont-Doherty Earth Observatory and its Engineering School. He studies the dynamics of climate and weather, especially in the tropics. In recent years he has become particularly focused on understanding the risks to society from extreme weather events and climate change. Sobel is author or co-author of over 200 peer-reviewed scientific articles; a book, Storm Surge (Harper-Collins), about Hurricane Sandy and climate change; and many op-eds and articles in the mainstream media, including the New York Times, CNN, Los Angeles Times, and many others. He has received awards from the American Meteorological Society, the AXA Research Fund, and the American Geophysical Union. He currently hosts a podcast, Deep Convection, featuring wide-ranging conversations with other climate scientists..