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Another in the series on the costs of inaction – what we’ll pay if climate change continues unabated 

Water is already a major concern in the Southwest, where homes, businesses and farms use far more water than is produced by rain and snowfall, and groundwater reserves are shrinking.

A recent study I completed with Elizabeth Stanton, quantifies the impact of climate change on the problem. It finds that without prompt action to reduce water usage, Arizona, California, Nevada, New Mexico, and Utah will face a combined shortfall of 1,815 million acre feet from population and income growth alone, plus 282 million to 439 million more from climate change – at a combined cost of as much as trillion. And that is assuming the shortfall can be made up at all. As conventional water sources dry up, the Southwest could find itself facing serious water crises in dry years, with unexpected disruptions that could devastate agriculture and affect homes and businesses as well. 

We also evaluated potential ways to meet the shortfall, including water imports, desalination and additional groundwater extraction, and conclude that none can solve the problem. To avoid serious water crises, the Southwestern states should promptly implement substantial conservation and efficiency measures as well as price increases for both urban and agricultural users. They should also begin phasing out low-value crops, some of which are worth less than the water used to grow them. 

A related study I completed with Jeremy Fisher examines the water-energy nexus in the U.S. West. Water and energy are deeply intertwined: production of electricity requires water, and water supply requires electricity. Demand for both is growing, while supply is constrained by limited resource availability, high costs, and the impacts of climate change. 

We modeled long-run scenarios for the eleven-state Western Electric Coordinating Council, stretching from the Pacific coast through Montana, Wyoming, Colorado, and New Mexico. We projected power plant construction and operation, focusing on costs, water use, and greenhouse gas emissions, from now through 2100.  In each energy scenario, demand is based on state population trends, and on temperature forecasts from climate scenarios. Supply is initially based on existing power plants, shifting toward a new fuel mix as new plants are built, with different fuel mixes depending on policy choices. 

We defined four scenarios: business as usual (BAU); water reduction; carbon cap; and both water and carbon limits. The most surprising conclusion was the relatively small difference between scenarios in total water consumption. The maximum impact, or difference between the most and least water-intensive energy scenarios, was less than 1.2 million acre-feet of water per year by 2100 for the eleven-state region as a whole. 

The model also shows the range of carbon and water prices that could drive the market toward low-carbon and low-water choices. A carbon price of $70 per ton of carbon dioxide makes the carbon-reducing scenarios lower in cost; a water price of $4,000 to $7,000 per acre foot is needed to make the water-conserving scenarios lower in cost. The latter is well beyond the range of current costs for virtually all water transactions. 

What can we conclude from these two studies?  Climate change is affecting Americans in many areas; the water crisis in the Southwest is one of the clearest examples. Climate policy choices we make today are not just about exotic environments and far-future generations – they will help determine how easy or hard it is to create a sustainable water system in the most arid region of the country.

Download the two reports here:

The Last Drop: Climate Change and the Southwest Water Crisis – Stockholm Environment Institute- US

The Water-Energy Nexus in the Western States: Projections to 2100 - Stockholm Environment Institute- US