The Modernist Anthropocene examines how modernist writers forged new and innovative ways of responding to rapidly changing planetary conditions and emergent ideas about nonhuman life, environmental change and the human species. Drawing on ecocritical analysis, posthumanist theory, archival research and environmental history, this book resituates key works of modernist fiction within the ecological moment of the early twentieth century, a period in which new configurations of the relationship between human life and the natural world were migrating between the sciences, philosophy and literary culture. The author makes the case that the early twentieth century is pivotal in our understanding of the Anthropocene both as a planetary epoch and a critical concept. In doing so, he positions James Joyce, Djuna Barnes and Virginia Woolf as theorists of the modernist Anthropocene, showing how their oeuvres are shaped by, and actively respond to, changing ideas about the nonhuman that continue to reverberate today.