Seasonal snowpack melt is an essential source of fresh water, and its loss could threaten drinking water supplies, agricultural irrigation and wildlife ecosystems. Stanford University climate expert Noah Diffenbaugh led the study, which compares snowpack conditions across the northern hemisphere in the late 20th century with climate model projections for the next one hundred years.
Those projections are based on a range of scenarios which foresee a rise in average global temperatures of between two and four degrees Celsius. The study concludes that average snow accumulation will decrease in most regions of the Western United States, Europe, Central Asia and the Himalayas, compared to historical patterns.
It projects that low and extremely low snow falls would exceed the lows of the later 20th century between 10 and 30 percent of the time with two degrees of warming. And, Diffenbaugh says, "If the planet warms by 4 degrees Celsius, the United could experience snowpack accumulations below the levels of the late 20th century up to 80 percent of the years.” The story is the same in other parts of the northern hemisphere, where snowpack is a natural, and critical, water reservoir.
The study finds that an early spring melt would bring more water into the watershed sooner than usual, potentially flooding rivers, lakes and artificially dammed-river reservoirs. And with less water available later in the season, chances for more wildfires, pests, and species extinctions increase. Diffenbaugh says this timing would also exacerbate drought conditions when the demand for water is greatest. “We can infer that should these physical climate changes occur in the future, that there would be impacts on water supply for agriculture and for human consumption and for natural ecosystems if the water storage and management systems are not adapted to those changes.”