The California Drought: Causes, Predictions and Infrastructure

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Over 99 percent of the state of California is abnormally dry. Image by the National Drought Mitigation Center.

You may have seen images of fires lighting up the nighttime sky in California caused by their historic drought. So just how bad are things?

So bad that “drought shaming,” where neighbors report or publicly shame their neighbors or celebrities for water over-usage via social media, is now officially a thing.

How Severe is the Drought?

Over 71 percent of the state is experiencing extreme drought conditions, and 46 percent is experiencing exceptional drought, the most severe drought category.

This extreme drought has stressed the fresh water supply and made conditions ideal for wildfires across much of the state. According to the Weekly Drought Brief from the state of California, as of Wednesday, September 2nd, 2015:

Since the beginning of the year, firefighters from CAL FIRE have responded to over 4,743 wildfires across the state, burning 146,279 acres. Fire activity across California remains high with nearly 272 wildfires in just the past week.”

Also,

“With California in its fourth year of a severe, hot drought, the Governor’s Drought Task Force continues to monitor and identify communities and local water systems in danger of running out of water. As of August 26, approximately 2,257 wells statewide have been identified as critical or dry, which affects an estimated 11,285 residents. Cal OES has reported that 2,160 of the 2,257 dry wells are concentrated in the inland regions within the Central Valley.

Causes of the Drought in California

The drought is believed to be caused in part by a mass of warm water in the Pacific Ocean that has drifted closer to the West Coast recently. The warm water formation, known as “the blob,” has persisted in about the same location for over two years, and is about a thousand miles across and 300 feet deep.

La Niña likely kicked off the drought cycle in 2011 by creating a persistent high-pressure system just off of the West Coast, close to California. The high-pressure system interfered with storm tracks and wind flow, causing storms that would usually have hit California to chart a different course and drench other locations with their much-needed precipitation.

The high-pressure system created by La Niña also rerouted cold air away from this location over the Pacific, which prevented the atmosphere from removing the usual amount of heat from the ocean, contributing to “the blob.”

Another factor influencing the drought is the form of precipitation – because of the way water resources are managed in California, snow is more beneficial than rain for drought relief. California relies upon the buildup of a snowpack in the winter to melt into runoff in the spring for the state’s water supply.

Unfortunately, the blob, which is two to seven degrees Fahrenheit warmer than usual for water in that part of the ocean, heats the atmosphere above it, making rain more likely than snow. During this drought, California has had record-high temperatures and record-low snowpack depths.

Drought Predictions Through the End of November 2015

The likelihood of the drought continuing depends mainly upon three things: Current conditions, precipitation and temperature forecasts, and El Niño.

Although parts of southern California had record rainfall in July due to moisture left over in the atmosphere from Hurricane Delores, it was not enough to counteract the long-term drought conditions. The state is currently in a very deep precipitation deficit, and would need a lot of precipitation (preferably in the form of snow) to compensate for it. Also, September, October and November tend to be dry months on average for most of the U.S., and California is no exception.

We’re currently experiencing an unusually strong El Niño, which has a 90 percent chance of continuing through winter 2015 and a 70 percent chance of continuing into the spring of 2016. Conventional wisdom has it that El Niño is a drought-buster for the West Coast and Southwest United States. However, it is premature to assume that this will halt the drought since, historically, years with similar El Niño signals only have a track record of bringing about a wetter winter than usual about half of the time.

Shifts in El Niño due to climate change make it an even less certain proposition, so it is optimistic to say that there is even a 50 percent chance that this year’s El Niño will reverse drought conditions in California in the next few months.

The Climate Prediction Center expects that long-term hydrological drought is likely to continue in California (and the Far West in general).

Infrastructure Also Matters

Let’s say El Niño comes in all its glory, fulfilling the best case scenario and dumping much-needed precipitation on the state of California. Do we all rejoice – end of story? Unfortunately, it’s not so simple – for two main reasons.

First of all, El Niño tends to bring more warm winter storms than snow, which do not build up the snowpack. And because this year is hotter than previous years with similar El Niño signals, precipitation is even more likely to materialize in the form of rain rather than snow this time around.

Secondly, water systems in California (and much of the West) aren’t equipped to make use of heavy rainfall. The infrastructure is set up to move drenching rains off of land and into the oceans and quickly as possible to avoid flooding. This may seem like an oversight in a state that tends to be dry, but the system worked fine as long as it could rely on a consistent snowpack. Most of California’s water supply comes from snowmelt captured and stored from the Sierra Nevada Mountains in reservoirs and canals.

Ending the California Drought

As humans, we can’t fight “the blob” or bring an end to the drought. We can, however, change our infrastructure to adapt not just for the current drought, but for future droughts that will inevitably become more frequent in the region due to climate change.

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