How do we know about the global environmental challenges we currently face? Climate fires, extreme weather, the vast acceleration of the disappearance of species, the impending collapse of the West Antarctic ice sheet: how do we make visible large-scale problems and complex evidence? And how do we communicate findings and potential solutions to the wider world in our age of environmental anxiety? This course studies the public communication of knowledge about the large-scale environmental challenges of the climate crisis, biodiversity loss, and the intersections of environment and social justice. It will focus on climate change communication, data visualizations, ‘social math’ that places large numbers in social contexts to make them meaningful, and the possible limits of these methods. Students will explore and critique the very different efforts underway to communicate big data and knowledge about urgent environmental problems to a broad public, and use these to design their own.