Rising global temperatures are likely to shrink snowpacks in the Northern Hemisphere aggressively and sooner than previously thought, with some changes coming in the next 30 years, a new study out of Stanford University says.
It would have major implications for water supplies that are used for drinking, agriculture and in some places hydropowered-electricity, experts said. It is also likely to affect the ability to control floods, as snowpack that melts earlier in the year increases downhill runoff. There could also be more rain versus precipitation stored on the mountains through the winter as snow.
That would affect how much water is available in spring and summer, potentially increasing how often very dry years occur.
"While reduced snowpack has been predicted for some time, they find that the shift toward low snow years and increasing water stress in the Northern Hemisphere is 'imminent,'" said Andrew Fahlund, executive director of the Water in the West program at Stanford. "Essentially, they are showing that what we have come to know as 'low water years' in the past are going to become the new normal in fairly short order.
"What we've come to know as 'extreme drought' years -- relatively rare in the time that the western U.S. has developed -- are going to become more common," Fahlund added.
The research, published Sunday in the journal Nature Climate Change, synthesized data from 55 climate model simulations that have recently become available. The study looked at how warming will affect snowpack in the western United States, Alpine Europe, Central Asia and downstream of the Himalayas and Tibetan Plateau. More than 50 percent of the world's population lives in those places, Stanford said.
Major impact on West Coast
The western United States and Canada, South Asia and parts of north and central Eurasia will be the most affected, said lead author Noah Diffenbaugh, an assistant professor at Stanford and a fellow at the school's Woods Institute for the Environment.
The study examined what is likely to be seen in terms of precipitation, snowpack accumulation and water runoff over the next century, versus the same data for the years from 1976 and 2005. It compared the future to the lowest snowpack year seen over that recent 30-year span.
"We've looked at the extremes of snow accumulation and melt," Diffenbaugh said. "If we look at the lowest spring runoff that occurred over late 20th century, how often do we expect to see values lower than that" in the future?