Policy making in the face of climate change poses several specific decision-theoretic challenges. Policy makers may not be fully sure about what the options are; they visibly lack sufficient information to make precise uncontroversial judgements about the probabilities of relevant events or the utilities of possible outcomes; they may even be unaware of some pertinent contingencies. We use the term �severe uncertainty� to denote decisions with these characteristics. Decisions in the face of climate change, of the sort that will be taken this year and in the years ahead, are decisions under severe uncertainty par excellence.

How should decisions be taken in such situations? What is the best way to represent uncertainties that cannot be reduced to a precise probability, and how should decision makers incorporate such imprecision into their choices? How should one deal with uncertainties about the options available, or the value of possible outcomes? How can mitigate potentially relevant but unforeseen contingencies?

Over the past few decades, and with renewed interest and vigour in the past few years, general questions of this sort have been posed and studied by various domains. The aim of this workshop is to bring together experts in decision working in various fields (mainly economics and philosophy) as well as theorists in climate policy to present recent results and perspectives, lay the ground for inter-disciplinary collaboration and exchange, and define the challenges and priorities for future research.

The workshop, called Decision Making under Severe Uncertainty, will be held at the London School of Economics and Political Science on the 19th and 20th June 2015. It is organised under the joint auspices of two recent projects dedicated to both developing theoretical research on decision making under severe uncertainty and building bridges to applications in decisions such as those climate policy: the ARHC-funded Managing Severe Uncertainty project based at the LSE (UK) and the ANR-funded DUSUCA project based at GREGHEC (HEC Paris, CNRS; France). It will hopefully the first in a series of events at the crossroads of theory and application, of research and policy, of philosophy and economics but also (for future workshops) of climate science, statistics and risk management.