The relentless heat that has plagued the western half of the country this summer has ratcheted up California’s terrible drought once again, bringing it to record levels. More than half of the state is in “exceptional” drought, the highest category recognized by the U.S. Drought Monitor, which released its latest update on Thursday.
“The heat has been and continues to be a factor in drought expansion,” Brad Rippey, a meteorologist with the U.S. Department of Agriculture and this week’s Drought Monitor author, told Climate Central.
New information coming in about reservoir levels, stream flows and Record-Setting Drought Intensifies in Parched California prompted Rippey to increase the amount of California covered by exceptional drought to 58 percent from 34 percent (all of the state is in some level of drought). That is a record amount of the state covered by this level of drought since the Monitor began in 1990.
While the drought can’t be directly linked to climate change, the warming of the planet is expected to make already dry places drier. And future droughts could be even worse.
The current drought — which rivals the terrible drought of the late 1970s — has been 3 years in the making, as three successive winter wet seasons went by with below-normal rainfall. The paltry snowpack this year really intensified matters, and the persistent pattern of heat in the West and cold in the East has kept much of California baking all year. In fact, the state had its warmest first six months of a year on record this year. July has followed suit with, for example, San Francisco registering an uncharacteristic 90°F on July 25, a full 12°F above normal.
“Excessive heat this time of year leads to heavy irrigation demands, deteriorating rangeland and pasture conditions, and higher evaporation rates,” Rippey wrote in an email.
These effects of the heat further reduce reservoir levels and stream flows and can send more towns and farmers in search of groundwater to pump. Reports of such changes can slowly trickle in as the impacts intensify and give the Drought Monitor authors reason to upgrade the level of drought in an area, or in this case, over a large swath of Northern California.
Reservoir storage in the state currently sits at about 60 percent of its normal level, above the record low of 41 percent set in 1977, but short about a year’s worth of reservoir storage. That shortfall is the result of the abysmal rains over the past 3 years: From July 1, 2011, to June 30, 2014, statewide precipitation averaged 45.05 inches, which was a record low.
“Effectively, only about 2 years of precipitation fell in that 3-year period from July 2011 to June 2014,” Rippey said.
(MORE: NASA Photos Show How Bad California’s Drought Has Gotten)
With such dismal numbers, water conservation is key.
“Conservation is certainly critical from this point forward, especially if drought-easing precipitation does not materialize during the 2014-15 cold season,” he said.
The state recently enacted mandatory water restrictions after a call for voluntary conservation failed to move the needle. For example, new regulations call for local agencies to fine anyone found wasting water up to $500 per day.
The depth of the drought and the heat have both helped fuel wildfires in the state, including a fire raging in Yosemite National Park that is 58 percent contained.
Officials have been hoping that a developing El Niño, currently foundering, would bring some relief in the form of winter rains this coming winter. But only strong El Niños are well correlated with rainier-than-normal conditions over Southern California, and this El Niño is looking less and less like it will be a strong one. However, even a weak or moderate El Niño could mean the wet season hits somewhat close to normal rainfall numbers.