Climate change is likely to have substantial effects on irrigated agriculture. It is anticipated that many areas that are already dry will become drier, while areas that already receive high rainfall may experience further increases. Extreme climate events such as droughts are likely to become more common. These patterns are evident in projections of climate change for the Murray–Darling Basin in Australia. To understand the effects of climate change, as modified by mitigation and adaptation, active management responses designed to improve returns in particular states of nature, such as in the case of drought must be considered. A change in the frequency of drought will induce a change in the allocation of land and water between productive activities. Even with action to stabilize atmospheric concentrations of CO2 at or near current levels, climate change will continue for some decades and adaptation will therefore be necessary. Conversely, most adaptation strategies are feasible only if the rate and extent of climate change is limited by mitigation. In this paper, a simulation model of state-contingent production is used to analyze these issues.