This paper explores the extent to which participatory budgeting (PB) contributes to climate change adaptation and mitigation, based on an analysis of initiatives from 15 cities and regions in the global South and North. PB contributions are far from marginal, with significant investments decided by local people. The paper highlights some of the numerous innovations introduced to integrate PB into climate adaptation and mitigation efforts. Through a scrutiny of 4,400 PB projects, the research identified six categories of climate-related projects encompassing hardware as well as software approaches, such as awareness-raising activities, community-based early warning projects and research. The paper advocates for solidarity PBs for climate justice, and raises awareness of the huge (and as yet largely untapped) potential for this to help address the dramatic impacts that climate change has on millions of people's lives. It also points to questions for future research.