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Snowpack Decline

Global warming affects snow and ice cover by increasing the amount of precipitation falling as rain instead of snow and by hastening snowmelt. Scientists have already observed these trends in the Western US. Atmospheric circulation may also be leading to an overall decrease in the amount of precipitation.

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Global snowpack decline trends

Snow and ice cover have diminished globally, and Northern Hemisphere spring snowpack decline cover is particularly noticeable. Scientists agree, human-caused global warming is the dominant cause.[1]

Northern Hemisphere snow cover extent decreased 1.6 percent per decade for March and April, and 11.7 percent per decade for June, over the 1967 to 2012 period.[1] The area of Northern Hemisphere spring snow cover is projected to decrease by 7 to 25 percent by the end of the 21st century, depending on the level of future emissions reductions.[1]

California snowpack decline trends

California has experienced climate change-amplified loss of snowpack due to higher temperatures that are accelerating spring melt and increasing the amount of precipitation falling as rain instead of snow.[2]

During the 2014-2015 water season—and for the first time in 120 years of record keeping—the winter average minimum temperature in the Sierra Nevada was above freezing, helping to explain the season’s record-low snowpack.[3] At Donner Summit in the Sierras, end-of-season snowpack on April 1, 2015 was the lowest on record, at only 0.51 inches (1.3 cm), or less than 2 percent of the long-term average.[4]

California’s diminished and faster-melting snowpack amplifies drought by lowering streamflow later in the spring and summer. The melting snow accounts for much of the seasonal water supply. In normal years, snowpack provides about a third of the state’s total water supply.[5] The greater the spring snowpack water content, the greater the likelihood California’s reservoirs and rivers will receive ample late spring and early summer runoff as the snowpack melts to meet the state’s water demand in the summer and fall.

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Air Mass Temperature Increase
Arctic Amplification
Extreme Heat and Heat Waves
Glacier and Ice Sheet Melt
Global Warming
Greenhouse Gas Emissions
Land Ice and Snow Cover Decline
Land Surface Temperature Increase
Permafrost Thaw
Precipitation Falls as Rain Instead of Snow
Sea Ice Decline
Sea Surface Temperature Increase
Season Creep/ Phenology Change
Snowpack Decline
Snowpack Melting Earlier and/or Faster
Atmospheric Moisture Increase
Extreme Precipitation Increase
Runoff and Flood Risk Increase
Total Precipitation Increase
Atmospheric Blocking Increase
Atmospheric River Change
Extreme El Niño Frequency Increase
Gulf Stream System Weakening
Hadley Cell Expansion
Large Scale Global Circulation Change/ Dynamical Changes
North Atlantic Surface Temperature Decrease
Ocean Acidification Increase
Southwestern US Precipitation Decrease
Surface Ozone Change
Surface Wind Speed Change
Drought Risk Increase
Land Surface Drying Increase
Intense Atlantic Hurricane Frequency Increase
Intense Cyclone, Hurricane, Typhoon Frequency Increase
Intense Northwest Pacific Typhoon Frequency Increase
Tropical Cyclone Steering Change
Wildfire Risk Increase
Coastal Flooding Increase
Sea Level Rise
Air Mass Temperature Increase
Storm Surge Increase
Thermal Expansion of the Ocean
Winter Storm Risk Increase
Coral Bleaching Increase
Habitat Shift or Decline
Parasite, Bacteria and Virus Population Increase
Pine Beetle Outbreaks
Heat-Related Illness Increase
Infectious Gastrointestinal Disease Risk Increase
Respiratory Disease Risk Increase
Vector-Borne Disease Risk Increase
Storm Intensity Increase
Tornado Risk Increase
Wind Damage Risk Increase
What are Climate Signals?