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Saturday, December 2, 2023

Extreme Heat Could Also Mean Power and Water Shortages

Across the Western United States, signs of a parched present—and future—are everywhere. From wildfires burning across the Pacific Northwest to California’s shrinking reservoirs, it appears as if the earth is extremely dry for the second summer in a row. As of July 22, 75.6 million people are living under drought conditions, according to the US Drought Monitor, a report produced weekly by hydrology experts at the National Oceanic and Atmospheric Administration, the US Department of Agriculture, and the National Drought Mitigation Center at the University of Nebraska, Lincoln. One quarter of the continental US is experiencing “extreme or extraordinary drought,” according to the report.

Despite some summer rains in parts of the desert Southwest earlier in July, experts say the situation is likely to get worse in the coming months, and that the region’s cities and farms should prepare for possible shortages of both electricity and water. “The spatial coverage of drought in the West is huge right now,” says Dan McEvoy, assistant professor of climatology at the Desert Research Institute in Nevada, who studies the causes and effects of western droughts. “Nearly every state, or every state in the western US, has some level of drought. And California is pretty bad.”

As he spoke with WIRED during his vacation last week, Jay Lund, a professor of civil engineering at UC Davis, was sailing his family’s 36-foot boat past a brand-new 800-foot rock wall across a section of the San Francisco Bay Delta. The 1,100-square-mile delta forms at the confluence of the Sacramento and San Joaquin Rivers and is home to 750 species of plants and wildlife. But because of the lack of rainfall this year, and lower snowpack in the Sierra Nevada mountains, the two rivers aren’t flowing enough to keep saltwater from the nearby San Francisco Bay flowing upstream and entering the delta. “This is an extreme drought,” Lund said while waiting for a breeze to pick up—the third driest on record in California, behind the droughts of 1976 and 1924, since record-keeping began in the early 20th century.

The sparse rainfall and low water levels are one reason that state officials in June built a $10 million emergency project—the size of San Francisco’s Transamerica Pyramid laid on its side—to keep ocean saltwater from surging into the delta. They hope to protect its freshwater supplies, which are diverted to massive pumps that pipe drinking water to 27 million California residents from San Jose to Los Angeles, and irrigation water to farmers across the fertile Central Valley.

California has started limiting groundwater withdrawals for the state’s farmers, who account for $50 billion, or 3 percent, of the state’s GDP. But, so far, Governor Gavin Newsom has only encouraged, rather than required, state residents to cut home water use, such as lawn watering, by 15 percent.

Still, there are signs of a growing concern about the looming water crisis in the Golden State. Lund, who has developed large-scale models of the state’s water supply, says August will be hotter and drier, and he expects more demand on the state’s electric grid and less available water. “This is a warm drought, and the higher temperatures are going to make the air-conditioning load higher, particularly in the evening hours when energy from solar power tails off,” says Lund. “That’s the major threat.”

But, he says, there will be less surface water to drive hydropower dams in California. “My guess is that we're going to have half or less of the total hydropower than we normally have,” Lund says, “just because there's less rainfall.”

Officials at the federal Bureau of Reclamation reported this month that the West’s two big reservoirs—Lake Mead in Nevada and Arizona and Lake Powell in Utah and Colorado—are deteriorating toward “dead pool” status, where stored water is at such a low level it can’t spin the massive hydroelectric power generators buried in the dams. As a result, the agency has begun releasing upstream water from Flaming Gorge Reservoir in Wyoming and drawing from reservoirs in New Mexico and Colorado. They hope it will stop Lake Powell from dropping low enough to threaten Glen Canyon Dam’s hydropower-generating capability.

Later this summer, the agency is expected to announce the first-ever federal water restrictions for Arizona, Nevada, and California beginning in January 2022, according to reporting from the Associated Press.

During the last big drought that struck California, between 2012 and 2015, the state was able to draw on hydropower electricity supplies from the Pacific Northwest to make up for its own shortfalls. But that might be tougher this year because that region is also experiencing a crippling dry spell that has spawned out-of-control wildfires and damaged crops.

On July 18, Washington’s topsoil moisture was rated 98 percent “very short to short”—the driest on record since the beginning of the 21st century, according to the latest Drought Monitor report. Washington also led the country in “very poor” to “poor” soil conditions for rangeland and pastures, spring wheat, and barley, while similar dried-out crop conditions were reported in Montana, Arizona, Oregon, Utah, Nevada, and Wyoming.

Because of its snowpack and surface water from Canada, the US Northwest has water to meet its own electricity and irrigation demands, but not much extra, according to Doug Johnson, a spokesperson for the Bonneville Power Administration, which produces power for 8 western states from 31 federal dams and one nuclear plant. “It is a below-average water year, so we want to make sure everyone is focusing on their own set-up and not counting on a surplus,” Johnson said. “It’s not something that people can rely on. There will be some additional energy, but it depends from day to day and week to week.”

Last August, California suffered rolling power blackouts across the state after temperatures spiked, along with demand for air conditioning. The crisis was blamed on poor planning by the state’s utilities, as well as the worsening effects of climate change, which experts say has driven high temperatures and played a role in the drought. The perfect storm of low water supplies, extreme heat, and surging power demand will likely bend, if not break, the electrical grid in some areas, according to Jordan Kern, an assistant professor of forestry and environmental resources at North Carolina State University, who studies water, power, and climate change. In the coming weeks “if you get 115- or 120-degree heat in places out west,” Kern says, “especially in California where everyone uses air-conditioning, then they will run out of electricity.”

In the past, utilities like PG&E have been denounced for management failures related to blackouts, such as failing to tell customers that outages to reduce demand were imminent, and relying on power from plants that had been shut down. This year, the same utility announced plans last week to bury 10,000 miles of power lines to reduce the risk of wildfires igniting from sparking power lines.

Kern notes that climate change has made temperatures higher and worsened the effects of the drought. “One way to determine whether it’s a bad summer or there’s something different about the climate is to look at what’s happened in the past, '' Kern says. “If you went back 50 years and looked at summertime temperatures and plotted them in a bell curve, and then plotted this year, this year would be off the charts.”

Kern points out that a group of climate researchers from the US and Europe recently published a report stating that the extreme temperature “heat dome” that baked the Pacific Northwest in late June was virtually impossible without human-caused climate change. “Our results provide a strong warning,” stated the report by the World Weather Attribution group.

The western drought has gotten so bad that its effects are now visible from space. NASA has a pair of satellites called the Gravity Recovery and Climate Experiment (Grace) mission, which circle the globe in tandem, about 137 miles apart from each other. By taking precise distance measurements between the two satellites, scientists can estimate minute changes in Earth's gravity field under the satellites. Its strength varies depending on how much mass objects below the orbiters’ flight paths have and how far apart they are. As they pass over mountains, lakes, and groundwater aquifers, the gravity field of each object exerts a small tug on one of the satellites. Scientists can measure the distance between the two satellites down to the width of a human red blood cell, and thereby get an estimate of the change in gravity, and change in mass, of the bodies of water below.

“We are measuring changes in terrestrial water storage, including snowpack and groundwater,” says John Bolten, associate program manager for NASA’s Applied Sciences Water Resources Program. “The big picture is, if you do this over and over again, you get a sense of the trend of groundwater. We are seeing a significant negative trend in this drought.”

Data from Grace, as well as a separate satellite mission that measures deep soil moisture, is fed to the US Drought Monitor, as well as to individual state water managers to help them make better decisions about how best to use the precious resource for both farmers and city-dwellers. Bolten says the satellite monitoring is revealing that groundwater levels are being depleted in the US and in other parts of the world. “It doesn’t take a rocket scientist to tell you it’s at an unsustainable rate,” he says.

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