Maintaining Mountain Snowpacks Essential for Preserving Valuable Freshwater Resource

California’s current drought is entering its fourth year. According to the U.S. Drought Monitor, more than 94 percent of the state is in severe, extreme, or exceptional drought. Shrinking groundwater supplies and municipal wells throughout the state are severely impacting the San Joaquin Valley, the state’s agricultural heartland.

And Chile – which exports approximately 30% of its fresh fruit production every year, with much of it shipped to the United States – is in the midst of a historic 13-year drought.

Saving Snow, Freshwater by Curbing Greenhouse Gas Emissions
But the new study also suggests that low-to-no-snow in both the northern and southern midlatitude mountain ranges can be prevented if global warming is limited to essentially 2.5 degrees Celsius (4.5 degrees Fahrenheit), the researchers said.

Their analysis is based on Earth system models that simulate the various components of the climate, such as the atmosphere and land surface, to identify how mountain water cycles could continue to change through the 21st century, and what warming levels might give rise to a widespread and persistent low-to-no-snow future across the American Cordillera – a chain of mountain ranges spanning the western “backbone” of North America, Central America, and South America.

The researchers used computing resources at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC) to process and analyze data collected by climate researchers from all over the world through the Department of Energy’s CASCADE (Calibrated & Systematic Characterization, Attribution, & Detection of Extremes) project. (Post-analysis data from the study is available to the research community at NERSC.)

The closest to what Rhoades and his team considered to be “episodic low-to-no snow” conditions occurred in California between 2012 to 2016. The low snow and drought conditions in these years demonstrated the vulnerability of our water supply and, in part, led to the passing of the California Sustainable Groundwater Management Act, new approaches to water and agricultural management practices, and mandatory water cuts, Rhoades said.

Persistent low-to-no snow (10 years in a row) has yet to occur, but Rhoades said that water managers are already thinking about such a future. “They’re collaborating with scientists to come up with strategies to proactively rather than reactively manage water resources for the worst-case scenarios if we can’t mitigate greenhouse gas emissions to avoid certain warming levels. But the better strategy would be to prevent further warming by cutting greenhouse gas emissions,” he said.

For future studies, Rhoades plans to continue to examine and run new Earth system model simulations at even higher resolution “to give more spatial context of when and where snow loss might occur and what causes it,” he said, and investigate how every degree of warming might change other key drivers of the mountain-water cycle, such as the landfall location and intensity of atmospheric rivers, and mountain ecosystem responses.

He also plans to continue to work with water managers through the Department of Energy-funded HyperFACETS project to identify ways we can better prepare for a low-to-no snow future through new management strategies such as infrastructure hardening against drought and floods and managed aquifer recharge.

Rhoades is optimistic, citing research from another Berkeley Lab-led study that found reaching zero net emissions of carbon dioxide from energy and industry by 2050 can be accomplished by rebuilding the U.S. energy infrastructure to run primarily on renewable energy.

“It just requires the will and initiative to invest financial resources at the level of urgency that climate change demands, which means we need to start doing this today,” he said.