Warming takes toll on Utah snow, and it looks to get worse

What Bruce Tremper saw when he ventured into the Wasatch backcountry this spring surprised him.

Bare patches littered the winter landscape where he was used to seeing snow — even on high-elevation ridge tops.

In one of his last forecasts of the season for the Utah Avalanche Center, Tremper noted that this year might wind up being the worst for snowfall in the 67 years that records have been kept at the Alta Guard Station. It was certainly the worst in his 30-year experience of Utah snow seasons.

"I have never seen that before in April as far as I can remember," he said, recalling the recent trip up the canyon. "Last year, there was more snow on that same slope in July than there is this year in the first part of April."

While you could say Tremper's is just one person's observation, it echoes the theme of several recent scientific studies that paint a grim picture of Utah's famed mountain powder.

Climate change is withering the spring snowpack in the Mountain West — the Wasatch Range included — the studies suggest.

That's the trend discovered by Robert Gillies, Utah's state climatologist, and colleagues at Utah State University. Their paper, soon to be published in the American Meteorological Society's Journal of Climate, showed a 9 percent increase in the amount of precipitation that fell as rain rather than snow.

It is the most detailed and comprehensive scientific look at snow/rain patterns in Utah so far.

"Our climate trend," Gillies said, "is changing in Utah."

He and co-authors Simon Wang and Marty Booth examined the state's snow patterns with a variety of scientific measurements — with data points "up there in the millions," according to Gillies.

They relied on the statewide historical climate network, in addition to a comprehensive look at weather patterns and storm tracks. It gave them a way of double-, triple- and quadruple-checking their work.

And their findings also make sense in light of what is known about warming in Utah. According to the Utah Climate Center, during the past four decades global average temperatures have increased about 0.27 degree Fahrenheit each decade. Here in Utah, it's warmed twice as much.

Why study the issue from so many perspectives? The scientists were determined to discover the real trends within global climate cycles that come and go.

In USU's Utah Climate News this month, the problem is described as like trying to track the ebb and flow of tides when there are big waves coming in. In the case of the state's snow patterns, the waves are comparable to big weather features like the El Niño, La Niña and the Arctic Oscillation.

But the Utah scientists found that if you correct for those "waves," it is clear that a bigger fraction of precipitation is falling as rain instead of snow.

In addition, they saw a trend that storms were fewer in number but greater in intensity.

Bigger, stronger computers have made it possible for climate scientists to begin zeroing in on smaller and smaller areas. And what Gillies found with the snow/rain mix echoes what other scientists have seen with a broader, regional focus.

At the National Center for Atmospheric Research in Colorado, Synte Peacock's team has identified similar trends globally and in the Rockies. She, too, has a peer-reviewed paper slated to appear soon in the Journal of Climate that deals with the same trends.

Her group has animated the spring snow scenarios of the past and projected into the future with sophisticated computer models. The alarming results, illustrated in computer graphics, show that there will be years at a time during this century when the Rockies will probably be snow-free by March and April.

"It shows," Peacock said, "that in the spring in the Rockies, where we're used to consistent snow cover through the spring, it's likely that's going to be a thing of the past by 50 or 60 years from now."

Peacock pointed out that her projections about the future are based on a worst-case scenario of greenhouse-gas emissions, the human-caused factor of climate change. And, while some might suggest using more conservative projections, she points out that the observed trends in greenhouse-gas emissions — the increasing concentration of carbon dioxide, methane and other key gases in the atmosphere — have closely followed the rapid-warming trend that's actually been observed in recent years.

In short, reality is tracking closely to what the worst-case computer models have estimated.

"Things would be very different if we reduced our CO2 emissions," Peacock said.

Brian McInerney, a hydrologist with the National Weather Service, has read the Utah Climate Center's paper, and he agreed that the long-term trends point to less snow and more rain. Although he might not know exactly how that will pan out, he foresees changes ahead for all who rely on mountain snow.

"Our water supply and how we live in Utah is based on the Mountain snowpack," he said. "Without the winter snowpack we can't live the way we do."

The snow "waits there until we need it," McInerney said. "Then it melts and we store it in our reservoirs until we're ready to use it.

"If that changes," he wondered, "how do we handle that?"

At the Jordan Valley Water Conservancy District, General Manager Richard Bay says climate change impacts like this have been built into contingency plans even though it is unclear how the trend would affect the district's ability to serve its 700,000 customers.

If the rain falls at higher elevations than where it's traditionally fallen, then the district can rely on its reservoirs, such as Jordanelle and Deer Creek, Bay said. If it falls at lower elevations, then the district will look to groundwater storage.

Bay has heard the political arguments on both sides of the climate debate. But his take on the issue is purely practical. He calls the district's approach "adaptive management."

"It's hard to distinguish at this point what you can count on and what might happen," he said. "But that doesn't matter when you're a water manager because you still have to meet the demands of a growing population."

fahys@sltrib.com

Twitter: @judyfutah

Editors Note: The online simulation showing March-April snow over 250 years seems to indicate there will be no spring snow in the Wasatch as early as 2030. But researcher Synte Peacock of NCAR pointed out that, given current limits of computing power, the model only shows the big picture in the Rockies and not details about the spring snow in a small range like the Wasatch. The article was changed to address any misimpression.