A skillful early detection and warning system for severe and/or abrupt climate change would benefit both adaptation and preparedness. But what would a severe climate change early warning system look like? Important characteristics of dangerous climate shifts, like rate of onset, intensity, spatial distribution, and predictability, are little known but are the subject of growing research efforts. Some ad hoc forms of climate early warnings are already emerging, and attention now to lessons, positive and negative, from existing hazard warning systems would seem prudent. The nature of warnings for hazards like hurricanes, volcanoes, and asteroids is examined for lessons relevant to a climate change early detection and warning system. An initial analysis of the relationships among lead time, warning, and response for different profiles of severe and abrupt climate change is offered.