In 2016, concern among physicians about the health harms of climate change led to the founding of the Medical Society Consortium on Climate and Health, a coalition of medical societies and ultimately other health organizations, to publicly sound the alarm and address profound and growing health and equity consequences of climate change. Building on strong public trust in medical and other health professionals, in partnership with other health organizations, in 2019 the Consortium declared climate change a health emergency and now pursues a policy agenda of equitable climate solutions that protect and promote health. The health case for climate action is compelling because while solutions provide climate benefits in the future, many solutions provide powerful health benefits in the present, and primarily in communities taking such actions. The economic case is also compelling, with the cost of electricity from clean renewable sources now lower than fossil fuels, and the cost of inaction continuing to grow: Recent estimates of the health cost of climate change show it surpassing $800 billion per year. The Consortium supports decarbonizing the U.S. health sector and international efforts to convince the world's leaders to limit global warming to no more than 1.5C, which is the upper limit of the safe zone.