This summer’s extreme weather events remind us that climate change poses an existential threat to the planet. If unabated, it has the potential to produce catastrophic ecosystem and societal changes, and it already has had an adverse effect on public and individual health. Because it leads to population displacement, deprivation, malnutrition, exposure to hazardous materials and neurotoxins, and expansion of vector-borne infections that affect the nervous system, climate change is already affecting our professional work as neurologists and, more importantly, the lives of our patients. This is why we are joining other medical journal editors on a “call for urgent action to keep average global temperature increases below 1.5°C, halt the destruction of nature, and protect health,” and publishing this editorial, which will appear simultaneously in 233 scientific journals throughout the world in advance of this year’s UN General Assembly (September 2021), the UN Biodiversity Conference (October 2021), and the UN Climate Change Conference (November 2021). We hope that this international effort will contribute to the deliberations at these forums. We also hope that this editorial will encourage our readers to work in their community to find urgent, sustainable, and equitable solutions to the most pressing challenge of our time.