 Advantages  Context-independent, hence applicable regardless of source, medium, location, affected interests (“risk science”)  Calculable, hence comparable and fungible (risk- benefit analysis)  Communicable, within limits, especially through comparisons (relative risks)  Disadvantages  Same as above!!! 9/21/11ESPP-781

9/21/11ESPP-782

9/21/11ESPP-783

9/21/11ESPP-78 4

 Model uncertainty: right causal assumptions?  Climate change is anthropogenic, not caused by sunspots or random temperature fluctuations  Rats are like humans in responses to toxicity  Parameter uncertainty: correct choice of parameters?  Climate variation is related to carbon emissions from car use, deforestation, volcanoes; offset by aerosols  Measurement uncertainty: accurate, valid?  Role of instruments, simulations, “ ground truthing ” of satellite data, historical records, lay experience 9/21/11ESPP-785

9/21/11ESPP-786

 Actual (actuarial) risks:  Based on reliable aggregate statistics (e.g., common accidents, common causes of death)  Perceived risks:  Relative ordering of risk as compared with actual probabilities  Lay vs. expert risk perceptions:  Risks ranked differently across social groups 9/21/11ESPP-787

 Popular explanation: ignorance of facts, probabilities, science,  Psychological (experimental) explanations  Exaggerated fear of unknown  Fear of loss overrides hope of gain  Social explanations  Historical experience of institutions  Perceived lack of control  Unattended ethical concerns (Quist/Chapela) 9/21/11ESPP-788

9/21/11ESPP-789

9/21/11ESPP-7810

 What is problematic about defining risk as probability of harm X magnitude of harm?  The problem of characterization ▪ Models and their uncertainties  The problem of perception ▪ Lay versus expert assessments (Note: not the same as wrong vs. right!)  The problem of politics ▪ Differences in values, priorities, trust 9/21/11ESPP-7811

 Conventional (linear) account  Probability x magnitude of harm  Hazard + exposure  Impacts  Characterization and communication  Socially embedded (recursive) account  Risks arise within and from social practices  Risks are framed by culture  Risks are perceived in social and historical contexts 9/21/11ESPP-7812

9/21/11ESPP-7813