IMAGe Brown Bag Seminar - Slower snowmelt in a warmer world: Using observations and modeling to develop a new theory of hydrologic change

03/15/2017 - 12:00pm to 1:00pm
ML - Damon Room

 

Slower snowmelt in a warmer world: Using observations and modeling to develop a new theory of hydrologic change


Dr. Keith Musselman

NCAR

 

In many regions of the world, the melt of accumulated winter snowfall in forested and mountainous landscapes provides a critical water resource for streamflow and groundwater recharge. This seasonal resource is one of the fastest changing hydrologic features under global warming with broad impacts on economies, ecosystem function, and flood hazard. There is general consensus that projected warming will cause earlier snowmelt, but how snowmelt rates will respond to climate change is poorly known. I present snowpack observations from western North America illustrating that shallower snowpack melts earlier, and at lower rates, than deeper, later-lying snow-cover. The observations provide the context for a hypothesis of slower snowmelt in a warmer world. This hypothesis is tested using climate model simulations for both a control time period and re-run with a future climate scenario. The relative fraction of meltwater volume produced at high snowmelt rates is greatly reduced in a warmer climate. The reduction is caused by a contraction of the snowmelt season to a time of lower available energy, reducing by as much as 64% the snow-covered area exposed to energy sufficient to drive high snowmelt rates. These results have important implications on soil moisture deficits, vegetation stress, reduced basin water yield, and streamflow declines.

(Bring your lunch)