Climate

California Is Rationing Water Use For First Time Thanks To Climate Change

CREDIT: AP Photo/Rich Pedroncelli

This pole was supposed to measure snow.

On Wednesday, California Governor Jerry Brown walked into a meadow in the Sierra Nevada mountains with snow survey chief Frank Gehrke, who carried an extremely tall pole to measure snowpack depth. They wore hiking shoes instead of skis, which signaled a serious problem.

“We’re standing on dry grass,” Brown said. “We should be standing on five feet of snow.”

Standing on that dry land and facing a historic drought, Brown then demanded “unprecedented action.” That action took the form of California’s first-ever statewide mandatory water use restriction. Brown signed an executive order detailing to local water supply agencies how they could cut usage 25 percent from 2013 levels.

Last week Brown signed a $1.1 billion emergency drought relief bill, which could help localities meet the 25 percent water cuts outlined in the executive order. Brown said the order he was issuing was unique in its level of detail — the likes of which he’d “never seen … before.”

It directs the State Water Resources Control Board to implement water savings plans in cities and towns across the state to meet the 25 percent goal. Local water agencies will be changing their pricing structures to limit excess use. Landscaping will change from lawns to drought-tolerant vegetation across 50 million square acres of the state. Consumers can receive higher rebates for efficient appliances. And as desalination plants go up on the coast, urban areas can begin to reduce the drain on reservoirs.

Last year the state failed to achieve a voluntary 20 percent water use reduction, and while officials said punitive fines could be used to enforce the new guidelines, they expected not to have to resort to that.

The drought forcing these responses is now the worst on record.

California’s rainy season typically lasts from October to March, but instead of being flush full reservoirs and a healthy snowpack, the state has entered its fourth consecutive year of drought — the worst in 120 years of state recordkeeping. With the last week’s temperatures averaging more than 10°F hotter than normal, snowpack levels, already at five percent of normal, will continue to shrink at even faster rates. Five percent is less than one-third the previous record low: 25 percent of average set in 2014 and 1977.

“The west continued to cope with much-above-normal temperatures, further depleting already-dire snowpacks and reducing spring runoff prospects over much of the region,” reported the U.S. Drought Monitor on Thursday.

The Monitor noted that the last water year “ended on an abysmal note,” with 10 percent the normal precipitation levels over the last 30 days. It warned that additional precipitation “would likely do little to improve the state’s dire drought prospects.”

Even after the big storms that rolled through the state last December, it needed 11 trillion gallons of water to end the drought, a situation made worse as much of the precipitation fell as rain rather than snow.

The drought monitor map for the week ending on March 31, 2015, released on April 2.

The drought monitor map for the week ending on March 31, 2015, released on April 2.

CREDIT: U.S. Drought monitor

In April 2014, at the end of last year’s rainy season, 23 percent of the state was in “exceptional drought” — this year it’s 41 percent.

The snowpack usually supplies 30 percent of California’s water use, and 60 percent of the water needed to help fill the rest of the state’s traditional reservoirs. But water resource managers like Gehrke are essentially telling reservoir operators not to expect water from the snowpack this year.

When it comes to reducing the demand those reservoirs have to meet, the elephant in the room is agricultural water use, which accounts for 80 percent of the state’s yearly consumption. Gov. Brown’s executive order addresses farming mainly in the form of an increased enforcement against illegal water waste.

Big agricultural water consumers “will be required to report more water use information to state regulators, increasing the state’s ability to enforce against illegal diversions and waste and unreasonable use of water under today’s order,” a state press release said.

But large farms will not fall under the 25 percent guideline. The state is likely mindful of keeping food prices from rising more than they have, wary of cutting water allocations to large farms further. But finding ways to cut water use significantly will become more critical for California’s growers, as the drought is likely to get worse, not better.

One big reason is climate change.

When people ask why this drought has been so bad, and how much worse it could get, scientists point to two main factors: lack of rain, and extreme heat. Droughts happen when it does not rain, and they get worse with extreme heat. When half the years are warm, and half are cold, this is less of a problem. But with climate change pushing global temperatures higher and higher, it’s very likely that California has not seen the worst of it.

The climate change connection to this particular drought’s lack of rain may be less direct, though for each degree warmer the atmosphere gets, it can hold four percent more moisture. This means less frequent precipitation events as the air holds more water, though when it does rain, it rains a lot all at once, making it harder for the land to easily soak up the water.

Princeton climate scientist Michael Oppenheimer put it to the New York Times this way: “The rain deficit isn’t clearly connected to climate change, but the planetary warming has made it more likely that the weather would be hotter in California.”

A recent study noted that soil moisture levels are worse than they’ve been for more than a millennium: “the current event is the most severe drought in the last 1200 years, with single year (2014) and accumulated moisture deficits worse than any previous continuous span of dry years.”