ENVIRONMENT

The Sierra Nevada’s snowpack is at a 500-year low. No wonder why skiers, hikers, farmers, forests, and virtually every other living thing in California are feeling the effects. (Nat Geo News)

Learn more about California’s megadrought.

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.

Discussion Ideas

• How have scientists determined that this year’s snowpack is the lowest it has been in 500 years?
  • Scientists are using dendrochronology. Dendrochronology is the study of tree rings and how they can identify and date weather events and changes in the atmosphere. In particular, they are looking the the ancient rings of blue oak trees, endemic species that have thrived in what is now California for centuries. California’s beautiful blue oaks are “‘really really reliable recorders of the amount of rainfall that falls in the winter season, because they produce wide rings after wet winters.”
  • Dendrochronology shows that blue oak rings have never been narrower than in recent years.

• According to Nat Geo News, “The 2015 Sierra snow water equivalent was just 5 percent of average over the past 500 years.” What is the “snow water equivalent”? Read this handy guide from the good folks at Oregon’s Natural Resources Conservation Service for some help.
  • The snow water equivalent (SWE) is the amount of water contained within the snowpack. It can be thought of as the depth of liquid water that would result if you melted the entire snowpack instantaneously.
    • The depth of a snowpack is not the same as its SWE. SWE depends on a snowpack’s density. The density of new snow ranges from about 5% when the air temperature is -10°C (14°F), to about 20% when the temperature is 0°C (32°F). After snow falls, its density increases due to gravitational settling, wind packing, melting, and recrystallization.
      • [SWE] ÷ [Density] = Snow Depth

• How is California’s radically reduced snowpack impacting the state?
  • Environment. At least 18 species of native California fish, including salmon and steelhead trout, face imminent extinction if current conditions continue another two or three years. The 5 million birds migrating along the Pacific Flyway annually risk starvation and disease.
  • Health, Safety, and Convenience. Californians have cut their water use by a whopping 31 percent and are for the most part getting by this summer with short showers, yellow lawns, and infrequently flushed toilets. And the lack of snowpack could turn California’s summer and fall wildfire season into a year-round event.
  • Economy. California’s billion-dollar winter recreation industry (including ski resorts) relies on the heavy snowfall snowboarders nicknamed “Sierra Cement.” Farm losses could top $2.8 billion a year.

• Take a look at the great maps at USGS WaterWatch. What other regions are experiencing drastic droughts and low streamflow?
  • The entire West Coast, from California, through Oregon and Washington, is experiencing drought.
  • The Southern Appalachians, from southern Virginia to Mississippi, is also experiencing low streamflow.

TEACHERS’ TOOLKIT

Nat Geo: An Epic, 500-Year Snow Fail in California’s Iconic Mountains

Nat Geo: California’s Megadrought

NASA: Diminished Snow Pack in the Sierra Nevada

USDA: Natural Resources Conservation Service Oregon—What is snow water equivalent?

USGS: WaterWatch

(extra credit!) Nature Climate Change: Multi-century evaluation of Sierra Nevada snowpack