Nuclear power—a source of low-carbon electricity—is exposed to increasing risks from climate change. Intensifying storms, droughts, extreme precipitation, wildfires, higher temperatures, and sea-level rise threaten supply disruptions and facility damage. Approximately 64 percent of installed capacity commenced operation between thirty and forty-eight years ago, before climate change was considered in plant design or construction. Globally, 516 million people reside within a fifty mile (80 km) radius of at least one operating nuclear power plant, and 20 million reside within a ten mile (16 km) radius, and could face health and safety risks resulting from an extreme event induced by climate change. Roughly 41 percent of nuclear power plants operate near seacoasts, making them vulnerable to increasing storm intensity and sea-level rise. Inland plants face exposure to other climate risks, such as increasingly severe wildfires and warmer water temperatures. No entity has responsibility for conducting risk assessments that adequately evaluate the climate vulnerabilities of nuclear power and the subsequent threats to international energy security, the environment, and human health. A comprehensive risk assessment by international agencies and the development of national and international standards is necessary to mitigate risks for new and existing plants.