Most people assume that climate change is recent news. A Temperate Empire: Making Climate Change in Early America shows that we have been debating the science and politics of climate change for a long time, since before the age of industrialization. Focusing on attempts to transform New England’s and Nova Scotia’s environments from the seventeenth through early nineteenth centuries, this book explores the ways that early Americans studied and tried to remake local climates according to their plans for colonial settlement and economic development. For officials, landowners, naturalists, and other local elites, the Northeast’s frigid, long winters and short, muggy summers were persistent sources of anxiety. They became intensely interested in understanding the region’s natural history and, ultimately, in reducing their vulnerability to it. In the short term, European migrants from other northern countries would welcome the cold or, as one Loyalist from New Hampshire argued, the cold would moderate the supposedly fiery temperaments of Jamaicans deported to colonial Nova Scotia. Over the long term, however, the expansion of colonial farms was increasingly tempering the climate itself. A naturalist in Vermont agreed with Benjamin Franklin and Thomas Jefferson when he insisted that every cultivated part of America was already “more temperate, uniform, and equal” than before colonization—an eighteenth-century forecast of permanent, global warming they wholeheartedly welcomed. By pointing to such ironies, A Temperate Empire emphasizes the necessarily historical nature of the climate and our knowledge about it.