Articles | Volume 11, issue 6
The Cryosphere, 11, 2847–2866, 2017
The Cryosphere, 11, 2847–2866, 2017

Research article 11 Dec 2017

Research article | 11 Dec 2017

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

Keith N. Musselman1,a, Noah P. Molotch2,3, and Steven A. Margulis4 Keith N. Musselman et al.
  • 1National Center for Atmospheric Research, Boulder, CO, USA
  • 2Department of Geography, Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA
  • 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 4Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA
  • anow at: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA

Abstract. In a warmer climate, the fraction of annual meltwater produced at high melt rates in mountainous areas is projected to decline due to a contraction of the snow-cover season, causing melt to occur earlier and under lower energy conditions. How snowmelt rates, including extreme events relevant to flood risk, may respond to a range of warming over a mountain front is poorly known. We present a model sensitivity study of snowmelt response to warming across a 3600 m elevation gradient in the southern Sierra Nevada, USA. A snow model was run for three distinct years and verified against extensive ground observations. To simulate the impact of climate warming on meltwater production, measured meteorological conditions were modified by +1 to +6 °C. The total annual snow water volume exhibited linear reductions (−10 % °C−1) consistent with previous studies. However, the sensitivity of snowmelt rates to successive degrees of warming varied nonlinearly with elevation. Middle elevations and years with more snowfall were prone to the largest reductions in snowmelt rates, with lesser changes simulated at higher elevations. Importantly, simulated warming causes extreme daily snowmelt (99th percentiles) to increase in spatial extent and intensity, and shift from spring to winter. The results offer insight into the sensitivity of mountain snow water resources and how the rate and timing of water availability may change in a warmer climate. The identification of future climate conditions that may increase extreme melt events is needed to address the climate resilience of regional flood control systems.

Short summary
We present a study of how melt rates in the California Sierra Nevada respond to a range of warming projected for this century. Snowfall and melt were simulated for historical and modified (warmer) snow seasons. Winter melt occurs more frequently and more intensely, causing an increase in extreme winter melt. In a warmer climate, less snow persists into the spring, causing spring melt to be substantially lower. The results offer insight into how snow water resources may respond to climate change.