In 2025, global public health experienced a "polycrisis" driven by climate change, leading to resurging and novel disease threats. Warming temperatures facilitated the spread of vector-borne illnesses into new regions, while declining vaccination rates caused measles outbreaks in Europe and the US. Africa faced mpox clusters, and Latin America investigated zoonotic threats. Experts emphasize that climate change is a unifying driver, necessitating integrated surveillance and upstream interventions like land-use and climate policy, particularly for the Global South.