Economic impacts of climate change on water resources in the coterminous United States

A national-scale simulation-optimization model was created to generate estimates of economic impacts associated with changes in water supply and demand as influenced by climate change. Water balances were modeled for the 99 assessment sub-regions, and are presented for 18 water resource regions in the United States. Benefit functions are developed for irrigated agriculture, municipal and domestic water use, commercial and industrial water use, and hydroelectric power generation. Environmental flows below minimal levels required for environmental needs are assessed a penalty. As a demonstration of concept for the model, future climate is projected using a climate model ensemble for two greenhouse gas (GHG) emissions scenarios: a business-as-usual (BAU) scenario in which no new GHG controls are implemented, and an exemplary mitigation policy (POL) scenario in which future GHG emissions are mitigated. Damages are projected to grow less during the 21st century under the POL scenario than the BAU scenario. The largest impacts from climate change are projected to be on non-consumptive uses (e.g., environmental flows and hydropower) and relatively lower-valued consumptive uses (e.g., agriculture), as water is reallocated during reduced water availability conditions to supply domestic, commercial, and industrial uses with higher marginal values. Lower GHG concentrations associated with a mitigation policy will result in a smaller rise in temperature and thus less extensive damage to some water resource uses. However, hydropower, environmental flow penalty, and agriculture were shown to be sensitive to the change in runoff as well.