This dissertation studies literary modernism's philosophies of nature. It examines how historical attitudes about natural environments and climates are codified in literary texts, what values attach to them, and how relationships between humanity and nature are figured in modernist fiction. Attending less to nature itself than to concepts, ideologies, and aesthetic theories about nature, it argues that British modernism and ecology articulate shared concerns with the vitality of the earth, the shaping force of climate, and the need for new ways of understanding the natural world. Many of British modernism's most familiar texts, by E.M. Forster, James Joyce, Virginia Woolf, and H.G. Wells, reveal a sustained preoccupation with significant concepts in environmental and intellectual history, including competition between vitalist, holist, and mechanistic philosophies and science, global industrialization by the British Empire, and the emergence of ecology as a revolutionary means of ordering the physical world. "Modernism, Ecology, and the Anthropocene" uncovers these preoccupations to illustrate how consistently literary works leverage environmental ideologies and how pervasively literature shapes cultural and even scientific attitudes toward the natural world. Through the geological concept of the Anthropocene, it brings literary history into interdisciplinary conversations that have recently emerged from the Earth sciences and are now increasingly common in the humanities, social sciences, and in wider public debates about climate change. The dissertation's first chapter, "Connecting Earth to Empire: E. M. Forster's Changing Climate," argues that E.M. Forster's fiction apprehends the global implications of local climate change at a crucial time in environmental and literary history. By relating Forster's Howards End and A Passage to India to his 1909 story, "The Machine Stops," it attends to the speculative aspects of Forster's work and presents Forster as a keen observer who foresaw not only the passing of rural England and the arrival of a new urban way of life, but environmental change on a global scale. Its second chapter, "The Call of Life: James Joyce's Vitalist Aesthetics," explores the connotations "life" gathers in Joyce's early fiction and proposes a new reading of his aesthetics that emphasizes its ecological implications by pairing Joyce with his contemporary "modern" vitalism and current new materialisms. The third chapter, "Make it Whole: The Ecosystems of Virginia Woolf and A.G. Tansley," revises critical conceptions of Woolf as an ecological writer and environmental histories of early ecology by showing how Woolf's philosophy of nature and Tansley's ecosystem concept run parallel and represent a shared intellectual project: advocating theories of form and of perception that navigate the tension between holist and mechanistic conceptions of nature and mind. A final chapter, "Landlord of the Planet: H. G. Wells, Human Extinction, and Anthropocene Narratives," establishes Wells as an early environmental humanist whose ecological outlook evolved with his perception of the rapidly increasing pace of climate change and its threat to the human species. By digging into a rarely-read scientific textbook he co-authored, The Science of Life, this chapter analyzes how the natural world is managed in three Wellsian utopias and traces the development of his writing in concert with ecology.