Contemporary art is increasingly reverting to notions of the index to image the slow changes and catastrophic destructions caused by climate breakdown. Looking at Gideon Mendel’s photo series Watermarks (since 2011), Tomonari Nishikawa’s short film sound of a million insects, light of a thousand stars (2014), and Santiago Sierra’s installation 52 Canvases Exposed to Mexico City’s Air (2019), the essay analyzes three positions that employ analog techniques of direct exposure to the elements and to toxicity. They use the index to create artworks that function as collaborative testimonies of human and non-human witnessing work, prompting a re-reading of Rosalind Krauss’ two-part essay “Notes on the Index” (1977) for the present. Central to such a re-reading is the form the testimonies take on. I describe them as indexical abstractions, seeing in them images that are materially connected to the world yet expressing that involvement in non-mimetic ways. The works cite the idiom of abstract art not only to show that modernism has put the planet into distress but to also find a pictorial code operating beyond the confines of linear perspective. By doing so, they give expression to what Timothy Morton has called the hyperobject of climate change, creating pictures that combine image and imagination, thereby asking viewers to approach them – and the world they index – with care.