Recent decades have seen increased variability in diverse domains, such as the climate and asset prices. As more resources are required to cope with greater variability in the outside world, exposure to greater variability can make people feel that society is more vulnerable. This sense of vulnerability, in turn, can lead people to judge and punish wrongdoers more harshly. Studies 1a–2c found that people who were exposed to graphs representing greater variability were more willing to punish wrongdoers, both in domains that were related to the source of variability and those that were unrelated. Studies 3 and 4 found that people who experienced more variable dice rolls were more likely to punish unethical behaviors in hypothetical scenarios and in experimental games, even at a financial cost to themselves. Studies 5a and 5b provided evidence for the underlying mechanism — sense of vulnerability — using correlational designs. Study 6 provided experimental evidence for the underlying mechanism. These findings suggest that increasing variability in diverse domains can have unexpected psychological consequences.