The IPCC has concluded with high confidence that, by mid-century, precipitation changes owing to climate change will mean that less water will be available in already arid parts of the world, including the western United States. Climate change is contributing to snowpack losses and melting glaciers in the United States, leading to water shortages in the West. Addressing global warming could lessen the threat to these water resources.
Water shortages have wide-ranging consequences. For example, as sources of water used for irrigation dry up, the costs of producing food could rise. Lower water levels and higher temperatures in streams and rivers could diminish the capacity of hydropower and cause the collapse of some fisheries. And water prices could rise not only for farmers but also for industry and homeowners, especially in areas where growing populations are already putting stress on water resources, such as the southwest United States. Finally, because the concentration of pollutants increases when water levels drop, water shortfalls could also lower water quality.
An important note is that nuclear power and fossil fuel plants that produce electricity rely on vast quantities of water for cooling, while many climate-friendly renewable sources (excluding conventional biofuels) require far less water, leaving more for other purposes and making them better suited to a climate constrained world.