As heat-trapping greenhouse gases build-up in the atmosphere, the Northern Hemisphere cold pool shrinks, and winter temperatures warm, it would stand to reason that snowfall would decline.
Indeed, a report published Monday confirms an increasing percentage of winter precipitation is falling in the form of rain across the U.S.
The report was prepared by Climate Central, the science communication non-profit based in Princeton, N.J. Its analysis of 65 years of data at 2,000 weather stations in 42 states shows a large majority of states are experiencing more rain and less snow.
“[The shift towards more rain has] potentially severe consequences in western states where industries and cities depend on snowpack for water, and across the country wherever there is a winter sports economy,” the report’s executive summary said.
The report, “Meltdown: Increasing rain as a percentage of total winter precipitation”, found the greatest shifts towards more rain at lower elevations with less of a clear pattern in the high terrain.
This result is not surprising since lower elevations have milder average winter temperatures and more frequently straddle the rain-snow line compared to the mountains. In these low elevation locations, just a small increase in temperature can mean the difference between a blanket of snow and bare ground.
While some high elevation states, particularly in the Rockies and Southwest, have avoided the shift towards more rain, “it seems unlikely … given rising temperatures … that these states will resist forever the trend,” the report said.
Of the U.S. regions analyzed, low elevations of Pacific Northwest have seen the greatest decline in snow. “81 and 91 percent of stations under 2,000 feet in Washington and Oregon, respectively, show a trend toward a lower percentage of winter precipitation falling as snow,” the report said.
States in the Midwest and eastern U.S. have also witnessed a decline in the percentage of precipitation falling as snow, including two-thirds of the weather stations analyzed in Virginia and Maryland.
Climate Central’s findings are consistent with the Environmental Protection Agency’s 2015 climate change indicators report, which found: “Nearly 80 percent of the stations across the contiguous 48 states have experienced a decrease in the proportion of precipitation falling as snow [since 1949].”
An increasing trend towards more rain and less snow in future decades could prove challenging for the ski industry. “A study on Northeastern U.S. ski resorts estimates that only four out of 14 major ski resorts will remain profitable by 2100 under a higher-emissions scenario,” Climate Central’s report said.