Climate change makes drought recovery harder in western US


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Californians rejoiced this week when large drops of water began to fall from the sky for the first measurable time since spring, an annual soak that heralds the start of the rainy season after some of the hottest months. and the driest ever.

But as the rain began to fall on Tuesday night, Gov. Gavin Newsom did a curious thing: he issued a statewide drought emergency and authorized regulators to pass mandatory water restrictions at statewide if they wish.

Newsom’s order may seem jarring, especially as forecasters predict that up to 7 inches of rain could fall over parts of northern California’s mountains and the Central Valley this week. But experts say it makes sense to view drought as something not caused by the weather, but by climate change.

For decades, California has relied on rain and snow in winter to fill the state’s major rivers and streams in the spring, which then feed into a vast system of lakes that store water for consumption, agriculture. and energy production. But this annual mountain runoff is decreasing, mainly because it is hotter and drier, not just because it rains less.

California’s spring snowpack in the Sierra Nevada Mountains was 60% of its historical average. But the amount of water that reached the reservoirs was similar to 2015, when the snowpack was only 5% of its historical average. Almost all water officials expected this year to either evaporate into warmer air or be absorbed into drier soil.

“You don’t get into the type of drought we’re experiencing right now in the American West just because of… a few missed storms,” said Justin Mankin, geography professor at Dartmouth College and co-head of the Drought Task Force. at the National Oceanic and Atmospheric Administration. “A warm atmosphere evaporates more water from the earth’s surface (and) reduces (the) amount of water available for other uses, such as people, hydropower, and growing crops.”

California’s “water year” runs from October 1 to September 30. The just ended 2021 water year was the second driest on record. The one before was the fifth driest on record. Some of the state’s largest reservoirs are at record levels. Things are so bad in Lake Mendocino that state officials say it could be dry by next summer.

Even if California were to have above average rain and snow this winter, warming temperatures mean it probably won’t be enough to make up for all the water lost in California. Last year, California experienced its hottest monthly average temperatures on record across the state in June, July, and October 2020.

Jeanine Jones, interstate resources manager for the California Department of Water Resources, said people shouldn’t think of drought “as just that occasional thing that sometimes happens and then we go back to a wetter system.” .

“We’re really moving to a drier system, so, you know, dry is becoming the new normal,” she said. “Drought is not a short-term feature. Droughts take a long time to develop and usually persist for quite a long time. “

Water regulators have already ordered some farmers and other heavy users to stop withdrawing water from major rivers and streams in the state. Mandatory water restrictions for ordinary people could be next.

In July, Newsom asked people to voluntarily reduce their water consumption by 15%. In July and August, people cut 3.5%. Newsom issued an executive order on Tuesday allowing state regulators to impose mandatory restrictions, including banning people from washing their cars, using water to clean sidewalks and driveways, and refilling decorative fountains.

State officials have warned water agencies that they may not be getting water from state reservoirs this year, at least initially. It will be very difficult, said Dave Eggerton, executive director of the Association of California Water Agencies.

But he said he believes Californians will soon start saving more water with the help of a statewide conservation campaign, which will include messages on electronic signs along highways. very busy.

“It’s going to happen,” he said. “People are starting to get the message and they want to do their part. “

Copyright 2021 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

The subjects
Climate change in the United States

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