Extreme Weather Toolkit: Snow & Ice

Snow Explainer - Shifting Snow in the Warming U.S.

The timing, location, and amount of snowfall is shifting across the U.S. 

The frozen parts of Earth’s surface—including ice sheets, glaciers, sea ice, permafrost, and snow cover—have shrunk over recent decades due to human-caused warming. 

Snow keeps our planet cooler, makes up more than 50 percent of the water supply in the western U.S., and supports ecosystems, economies and cultures across the nation. 

Our warming atmosphere holds about 4% more moisture per 1°F of temperature rise. As winters warm, more of that extra moisture now falls as rain instead of snow at about 80% of 177 weather stations across the contiguous U.S. 

Between 1970-2019, snowfall decreased in the spring and fall for most of the U.S. Winter showed a mixed record with more snowfall in some cold northern regions.

Decades of shrinking snowpack has reduced snow-derived freshwater in the western U.S. by 15-30% since 1955. These trends could continue, with an additional 25% decline in snow-derived freshwater expected by 2050.

The latest IPCC reports conclude with near certainty that Northern Hemisphere snow cover extent and duration will continue to decrease as our climate continues to warm.

Climate models suggest that Northern Hemisphere snow cover will decrease at a rate of -8% per 1.8°F (1°C) of global surface air warming.