Climate change poses major threats to human health, human and animal populations, ecological stability, and human social, financial, and political stability and well-being. Observed health impacts of climate change include increased heat-related morbidity and mortality, expanded ranges and frequency of infectious disease outbreaks, malnutrition, trauma, violence and political conflict, mental health issues, and loss of community and social connections. Certain populations will experience disproportionate negative effects, including pregnant women, children, the elderly, marginalized groups such as racial and ethnic minorities, outdoor workers, those with chronic diseases, and those in economically disadvantaged communities. Climate change poses significant ethical challenges as well as challenges to global and health equity.