The Act of God Defense-the notion that climatic events like storms and floods beyond the control of humans can excuse a defendant's liability for a plaintiff's damages - has long been recognized in tort, admiralty, and (at least theoretically) environmental law. Climate change promises to increase the frequency and severity of the very climatic events historically considered Acts of God, and thus raises the question of whether and to what extent climate change will adversely impact the continued vitality of the Act of God Defense. The article explores how the Defense has developed and been applied in tort, admiralty, and environmental law, finding that the key concept driving the defense is foreseeability of the climatic event itself (Event Foreseeability) or of actions that could be taken to prevent or mitigate the effects of the event (Response Forseeability). By exploring the theoretical bases for the defense, it is clear that notion of foreseeability raises significant issues with the defense Climate change promises to increase Event Foreseeability, and with such increased knowledge of likely impacts, will in turn raise the required level of Response Foreseeability to the point that a defendant must engage in economically inefficient responses if it wants to retain the ability to assert the Defense. The article concludes that the theoretical problems with the defense, coupled with their amplification by climate change, will likely combine to reduce the applicability of the Act of God defense in a warmer world.