Chapter 3, “Witnessing Ecologies,” attends to the witnessing of more-than-human ecologies, as well as ecologies of witnessing. Investigating nonhuman witnessing in the context of climate catastrophe and nuclear war, the chapter proposes the term ecological trauma to describe the injurious and ongoing effects of the rupturing of relations that compose ecologies as living and changing assemblages of more-than-human entities and processes. Engaging with scholarship on trauma, climate change, media ecologies, ecology, and nuclear colonialism, this chapter examines nonhuman witnessing across several sites: intergovernmental climate change initiatives in the Pacific; environmental remote-sensing regimes; artistic works that engage with the scale of climate crisis; and the glassblowing work of Indigenous artist Yhonnie Scarce, which responds to nuclear weapons testing in Australia.