In 500 years of snow falling, melting and running into California rivers, there has not been s snowpack as pitiful as the one we've now been dealt. The ongoing drought afflicting the state has reached the point where it's an event exceptional on the scale of millennia. This chilling conclusion comes from a recently published study of tree rings in Nature. The study took two sets of tree ring data from central California trees sensitive to mountain snowpack to paint a picture of the Sierra Nevada going back 500 years.
One set of blue-oak tree ring data was used to reconstruct snowfall, with wider rings corresponding to wetter years, and another set was used to chart temperature, which also affects tree growth. Together, the data sets allowed the study's authors to estimate the amount of water in the spring snowpack dating back to 1500.
This won't tell us how deep the base was in Tahoe when the Treaty of Granada was signed, but it does give us a rough idea of how much water was coming down from the mountains into central California, which is a product of precipitation and temperature. That distinction is important for a year like 2015, which saw precipitation in the range of normal variability but had its snowpack wiped out by warm winter temperatures. Standing snowpack is like a natural reservoir; it builds snow during the winter that's released during warmer, drier months. When winter temperatures are too high, the rain or snowmelt overwhelms a man-made system that can only capture so much water.
More drought coverage:
This Has Been the Driest Winter in California Since 1950
11 Ways Sierra-at-Tahoe Is Fighting the California Drought
New Squaw Valley/Alpine Meadows Ski Pass Tackles Drought
The Worst Winter Ever? Sierra-at-Tahoe Closes Due to No Snow
Inside the High-Dollar Fight to Save California Skiing
This spring, snow levels in the Sierra Nevada were at 5 percent of the annual average, according to Nature, and some measuring sites were bare for the first time in 75 years. Both contemporary metrics offer a glimpse into the state of California's drought, but the Nature study takes context to a whole new level. It's not a great view.