John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
A majorly diminished Sierra Nevada snowpack is something we should get used to, say researchers.
The Sierra Nevada is inseparable from California’s survival. More than two-thirds of the state’s water comes from the mountains, much of it from winter snow melting in the warmer seasons and flowing down to agricultural operations, reservoirs, and millions of thirsty people.
However, if the weather continues to be hot and dry, soon there might not be enough powder to roll a snowball. After examining tree rings and historical snowpack records, researchers announced today in Nature Climate Change that the Sierras haven’t had this little snow in at least five centuries. And it’s vanished in such a quick and startling way, it’s almost as if an army of truck-driving thieves stole it away in the night.
The above shot from NASA’s Aqua satellite shows just how thin the snowpack has become since 2010. (The ongoing drought started around 2011.) Here’s another series depicting the mountains in 2011, 2013, and 2014, one of the driest years in state history:
The disappearing snow isn’t only a problem for water managers but homeowners and firefighters as well, as the parched land is a perfect environment for wildfires. And the situation isn’t likely to improve in the decades to come, the researchers warn.
“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” says the University of Arizona’s Valerie Trouet in a press release. “Anthropogenic warming is making the drought more severe.”
How much precipitation needs to fall to make the Sierras normal again? A “ton,” according to the folks at NOAA. The agency says that for the state’s agricultural heartland of San Joaquin Valley to hit its average moisture levels by next fall, California needs to have its wettest year in known history. Here’s more:
As of the end of August, California is running 5-year precipitation deficits (starting in October 2011) of 8 inches in the dry southeast to almost 50 inches along the north coast. In California, four year rainfall amounts (2011-2014) have been between 54-75% of normal during that time frame. To put the deficits into another perspective, every region in California is missing at least a year’s worth of precipitation. In fact, the south coast of California is missing almost two year’s worth of rain (1.82 years to be exact). This deficit isn’t so much a hole as a giant chasm….
For these regions to bring five year [precipitation] totals to the 50th percentile—the middle of the pack—every region in California would need record-breaking amounts of rain. The south coast of California would have to receive precipitation over 300% of normal (nearly 53 inches of rain)! But hey, that’s only a mere 14.95 inches higher than the current record for wettest water year ever.