As important as it is for science communicators to provide clear, relevant, accurate information, people’s views about climate change or vaccines or genetically modified food or chemicals or nuclear power, or so many other health and safety issues, are a blend of conscious reasoning about the factual evidence, and subconscious emotional interpretation of that evidence. The subjective nature of risk perception, which shapes the choices people make as individuals and together as a society, raises unique challenges and ethical issues for science communicators. At a time of rising science denialism, as researchers in Italy face manslaughter charges for how they handled risk communication around the 2009 L'Aquila earthquake, with the debate about climate change raging, this is a critically important issue. Topics to explore include: Why do people’s fears so often not match the evidence? What is the ethical obligation of science communication about risk? What is the latest research on risk perception? How can we integrate this research into science communication training? How does social media amplify or attenuate perceived risk?