Online science communities can serve as powerful platforms for advancing scientific knowledge, capacity, and outreach by increasing collaboration and information sharing among geographically distant peers, practitioners, and the public. Here, we examine the value and role of the Early Career Climate Forum (ECCF), a climate-focused online science community based in the United States dedicated to training and providing support to the next generation of climate scientists. In a survey of community users and contributors, we find that the ECCF played a unique role in providing users access to career resources as well as climate-related research and insights. Respondents also indicated that the ECCF provides them with a strong sense of community and a sense of hope for the future of climate science research. These findings highlight the importance of online science communities in shaping and supporting the next generation of scientists and practitioners working at the science-management interface on climate change issues