For much of the 20th century, vulnerability to deprivations of health has often been defined by geographical and economic factors. Those in wealthy, usually 'Northern' and 'Western', parts of the world have benefited from infrastructures, and accidents of geography and climate, which insulate them from many serious threats to health. Conversely, poorer people are typically exposed to more threats to health, and have lesser access to the infrastructures needed to safeguard them against the worst consequences of such exposure. However, in recent years the increasingly globalized nature of the world's economy, society and culture, combined with anthropogenic climate change and the evolution of antibiotic resistance, has begun to shift the boundaries that previously defined the categories of person threatened by many exogenous threats to health. In doing so, these factors expose both new and forgotten similarities between persons, and highlight the need for global cooperative responses to the existential threats posed by climate change and the evolution of antimicrobial resistance. In this article, we argue that these emerging health threats, in demonstrating the similarities that exist between even distant persons, provides a catalyst for global solidarity, which justifies, and provides motivation for, the establishment of solidaristic, cooperative global health infrastructures.