California’s Sierra Nevada mountains are experiencing a rapid loss of snowpack due to a combination of a warm winter and an ongoing extreme heat wave. State data indicates the snowpack is currently 48% of average for this time of year, a significant drop from 73% in late February.
A Shrinking Snowpack
The situation on the ground reflects the data. Newsha Ajami, a water expert, observed “a lot of bare land, bare mountain with no snow” while skiing near Lake Tahoe in early March, noting that many ski lifts were closed due to the lack of snow. This year’s snowpack is typically expected to peak around April 1, but measurements show it has been shrinking since February 25.
The diminished snowpack is linked to broader climate trends. Scientific research demonstrates that human-caused climate change is pushing snow lines higher in the mountains and altering the timing of runoff. Warming temperatures, driven by fossil fuels and greenhouse gases, are also contributing to longer and more intense heat waves.
The current heat wave is forecast to break records across the Southwest, with temperatures expected to be 15 to 30 degrees above normal. The National Weather Service warns of hazardous conditions along rivers due to rising water levels and swift currents caused by the accelerated snowmelt.
While the snowpack is significantly below average, precipitation this winter has been slightly above average statewide. California’s major reservoirs are currently at 122% of their average levels, benefiting from runoff from the previous three years.
Looking Ahead
Despite current reservoir levels, Ajami cautions that this does not guarantee long-term water security. She emphasizes the necessitate to rethink and reoperate existing water systems, including changes to dam operations and stormwater management. Efforts to improve forest and meadow health to enhance natural water absorption are also considered important.
The situation is further complicated by challenges facing the Colorado River, another crucial water source for Southern California. The river has been shrinking for the past quarter-century due to a megadrought worsened by rising temperatures, and the current snowpack in its upper watershed is only 59% of average. Ajami also noted that extreme heat causes not only faster melting but also sublimation, where snow turns directly into water vapor, and can lead to snow being absorbed into the ground before reaching streams and rivers.
Frequently Asked Questions
What is causing the rapid snowmelt?
The rapid snowmelt is being caused by a combination of a warm winter, which resulted in less snow accumulation, and an extreme heat wave currently impacting the West.
How much of California’s water supply comes from the Sierra snowpack?
On average, California relies on the Sierra snowpack for about 30% of its water.
What did Newsha Ajami observe in the Sierra Nevada in early March?
Newsha Ajami observed “a lot of bare land, bare mountain with no snow” and noted that many ski lifts were closed due to the lack of snow.
As climate change continues to impact the water cycle, how will California adapt its water management strategies to ensure a sustainable future?
