The paper "Declining Mountain Snowpack in Western North America" by Philip W. Mote, Alan F. Hamlet, Martyn P. Clark, and Dennis P. Lettenmaier examines the decline of mountain snowpack in western North America due to climate warming. The authors analyze snowpack data from 1950 to 1997, covering the entire West from the Continental Divide to the Pacific, and from central British Columbia to southern Arizona and New Mexico. They use both manual and automated snow course data, as well as climate data from nearby stations, to assess trends and compare them with a hydrologic model (VIC). Key findings include: - Snowpack has generally decreased, with the largest relative losses (over 50% in some areas) occurring in western Washington, western Oregon, and northern California. - The largest losses are in areas with lower elevations and warmer midwinter temperatures. - The decline is primarily driven by warming, with temperature trends being more significant than precipitation changes. - The VIC model, driven by observed climate data, shows similar trends to the observed data, confirming the role of climate change. - The spatial patterns of snowpack decline are consistent with climatic trends, particularly temperature increases. - The declines are expected to continue and even accelerate due to projected future warming, with faster losses in milder climates like the Cascades and slower losses in colder regions like the northern Rockies. The study highlights the importance of understanding these trends for assessing the impacts of climate change on water resources in the region.The paper "Declining Mountain Snowpack in Western North America" by Philip W. Mote, Alan F. Hamlet, Martyn P. Clark, and Dennis P. Lettenmaier examines the decline of mountain snowpack in western North America due to climate warming. The authors analyze snowpack data from 1950 to 1997, covering the entire West from the Continental Divide to the Pacific, and from central British Columbia to southern Arizona and New Mexico. They use both manual and automated snow course data, as well as climate data from nearby stations, to assess trends and compare them with a hydrologic model (VIC). Key findings include: - Snowpack has generally decreased, with the largest relative losses (over 50% in some areas) occurring in western Washington, western Oregon, and northern California. - The largest losses are in areas with lower elevations and warmer midwinter temperatures. - The decline is primarily driven by warming, with temperature trends being more significant than precipitation changes. - The VIC model, driven by observed climate data, shows similar trends to the observed data, confirming the role of climate change. - The spatial patterns of snowpack decline are consistent with climatic trends, particularly temperature increases. - The declines are expected to continue and even accelerate due to projected future warming, with faster losses in milder climates like the Cascades and slower losses in colder regions like the northern Rockies. The study highlights the importance of understanding these trends for assessing the impacts of climate change on water resources in the region.