Unduly optimistic views of the impacts of climate change on agriculture, drawing on the research of the 1990s, have helped to justify relatively complacent approaches to climate policy. In the last decade, newer research has identified more ominous climate threats to agriculture – which should call for a revised perspective on climate policy. We review three categories of climate impacts on agriculture. Carbon fertilization, while still seen as a benefit to most crops, is now estimated to be smaller than in earlier research. The effect of temperature increases on crops is now recognized to involve thresholds, beyond which yields per hectare will rapidly decline. Finally, changes in precipitation can be crucial – not only in cases of drought, but also in subtler shifts in timing and intensity of rainfall. Response to the climate crisis in agriculture will require adaptation to inescapable near-term trends, via the creation of heat-resistant and drought-resistant crops and cultivars whenever possible. Yet unchecked climate change would quickly reach levels at which adaption is no longer possible; it is also urgent to reduce greenhouse gas emissions as rapidly as possible, to limit future climate-related damages.