The climate crisis is also a health and humanitarian crisis, disproportionately impacting people in the world’s most climate-sensitive regions—mainly low- and low-middle income countries with the least capacity to respond. MSF and other humanitarian organizations witness the consequences daily. More frequent, intense weather events and a warming planet contribute to food and water scarcity, more severe and widespread disease outbreaks, and more injuries and preventable deaths. They also drive massive population displacement, with over 32 million people fleeing their homes in 2022 alone due to floods, drought, storms and fire—nearly triple the number displaced by violence and conflict. To mark Earth Day 2024 (22 April) we present a cross-section of work by MSF and collaborators, drawing from a range of data sources and from first-hand experience at our medical projects. Emphasizing the urgency of adapting humanitarian operations to the climate crisis, the collection also explores loss and damage through a health lens, proposes policies and practices for creating climate-resilient health organizations, and advocates for embedding fair, just ethics perspectives into humanitarian action and research on climate.