Sunday, February 2, 2014

Dry and Thirsty in California

According to the USDA Drought Monitor, the southwestern United States, particularly California, is suffering from a prolonged and rather exceptional drought.  Here is a map showing drought conditions across the United States with darker areas showing drought intensity:

Here is a closeup of California:

In total, 98.57 percent of the state is suffering from abnormally dry conditions or worse, up from 65.8 percent last year at the same time.  A shocking 67.1 percent of the state is suffering from an extreme or exceptional drought, up from zero percent last year at the same time, however, approximately 22 percent of the state was suffering from a severe drought in January 2013. 

Let's look at three details:

1.) The Central Sierra Snow Lab, located in the Sierra Nevada near Donner Pass reports only 8 inches of snow on the ground, the lowest snowpack for this point in January since 1946.

2.) In the D4 (exceptional drought) drought area between Monterey and Bakersfield, wells have run dry with municipalities having to drill deeper wells.  As well, rangelands have no grass cover, prompting farmers to sell off livestock.

3.) The State Water Project, part of the California Department of Water Resources which supplies water for 25 million Californians and 750,000 acres of irrigated farmland, announced that it has taken action to conserve the state's water resources, cutting allocations to farmers and people in the state's cities and towns.  Storage in the state's key reservoirs is lower than at this time in 1977, one of the two previous driest years on record.  Lake Oroville in Butte County is at 36 percent of its capacity (compared to an average of 55 percent) and San Luis Reservoir is at a mere 30 percent of its capacity (compared to an average of 39 percent).  Never before has the State Water Project announced a zero allocation to all 29 public water agencies that buy water from it. 

Here is a map showing the response of vegetation to the drought:

A total of 26.6 percent of the state shows moderate to extreme vegetation stress related to the current drought conditions as measured by the VegDRI or Vegetation Drought Response Index which is based on remote sensing, climate and biophysical data.  Last year at this time, only 14 percent of the state showed similar conditions.

Data from the National Oceanic and Atmospheric Administration (NOAA) shows us how this problem for California came about.  Here is a map showing the states ranked by the amount of precipitation they received during 2013:

California was the driest state overall and had the driest year on record, receiving only 7.38 inches of precipitation, 15.13 inches below average and 2.42 inches below the previous record dry year of 1898.  

Here is a map showing the states ranked by their average temperature during 2013:

California was the only state that had temperatures that were much above normal during 2013 and it was the warmest state in the continental United States.  California tied its twelfth warmest year with a statewide temperature that was 1.4 degrees Fahrenheit above average. 

Let's close by looking at the definition of climate:

"Climate is the average course or condition of the weather at a place usually over a period of years as exhibited by temperature, wind velocity, and precipitation."

Certainly, California's warm and extremely dry weather cannot be attributed to climate change since weather is a short-term phenomenon, however, since climate is defined by the average condition of the weather over a period of time, eventually all of the current data will become part of the climate record.  When enough of these anomalous conditions add up and become part of the average, eventually, it will become apparent whether climate is changing or we're just having a few years of anomalous weather.  Unfortunately, by then, it will be long past too late to do anything about it.  With California producing nearly half of the fruits, vegetables and nuts grown in the United States, the current drought is going to have a wide impact in any case.

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