A growing body of research suggests that digital multimodal composing can provide students multiple points of entry for making sense of local climate change issues and sharing their voices through digital activism. Building upon this scholarship, this study examined the processes of 32 small groups (n = 55) of 7th- and 8th-grade students as they co-created a wide range of multimodal projects (e.g., videos, podcasts, infographics, posters, and cartoons) that explored the environmental, ecological, and sociopolitical impacts of inequitable access to urban tree canopy and greenspace in their city. In particular, scholarship on onto-epistemic heterogeneity, critical place-based learning, and multimodality were integrated to gain an interdisciplinary understanding of how digital multimodal composing mediated students' sensemaking about urban forestry impacts on community health and ecological well-being. Data sources consisted of field notes, audio and video recordings, survey data, student interviews, and students' final multimodal projects. Through qualitative and multimodal data analysis, five main themes emerged for how multiple modes mediated students' sensemaking about critical urban forestry: (1) embracing tree equity for compelling stories, (2) engaging authentic audiences through storytelling, (3) perspective-taking through multiple modes, (4) exploring affective dimensions of urban heat islands, and (5) developing solutions for critical urban forestry issues. These findings contribute new insights into how digital multimodal storytelling can provide a productive way for students to make sense of climate justice issues and gain agency by experiencing multiple ways of knowing.