Winter precipitation will more often be rain, rather than snow

By Steve Scauzillo / sgvtribune.com

UCLA scientists predict global warming will reduce snowfall in Southern California mountains by 40 percent in less than 30 years, a climate shift that has serious policy implications, not the least being the loss of the quintessential “only in L.A.” experience of skiing the mountains by day and riding the surf at sunset.

The drop in snowfall will be noticeable in the southern Sierra, the Tehachapis, San Gabriels and San Bernardino mountains by the middle of the century if nothing is done to curb greenhouse gases, namely carbon dioxide produced by the burning of fossil fuels.

Even with all mitigation measures in place to fight global warming, snowfall will drop 30 percent, explained Alex Hall, UCLA professor of Atmospheric and Oceanic Science and author of a study released Friday predicting the effects of global warming in the LA basin.

When Hall’s modeling extends to the end of the century, snowfall drops by 70 percent if nothing is done, yet the loss of snow stabilizes at 30 percent with global mitigation efforts, he said.

Rising temperatures from trapped greenhouse gases will prevent the formation of snow in the mountains. Instead of snow, there will be rain — lots of it — that could cause flooding, mudslides and push mountain reservoirs to their limits, Hall said.

“It’s pretty simple: You warm things up, you melt snow and ice,” he said, adding that his research echoes other global warming studies in the West showing rising temperatures melting ice caps, glaciers and causing rapid snowmelt and flooding in the valleys.

In the worst-case scenario, Mt. Baldy, really Mt. San Antonio, would lose its snow-topped dome as well as its anthropomorphic nickname. However, the temperature drop won’t affect snowmaking at higher elevations. The most noticeable effect will be no more dusting of the upper foothills of the San Gabriel and Santa Monica mountains. Here, instead of snow, warmer temperatures would create rain.

Aside from not snapping that picture-postcard mountain shot, Angelenos would have less reason to drive up Angeles Crest or to Frazier Park to frolic in the snow. Also, ski resorts in Wrightwood and Big Bear would see less natural snow on the runs, the study predicts.

“It is possible to infer that there would be pretty significant impacts on winter tourism, on businesses that rely on winter sports like skiing and snowboarding,” Hall said.

The L.A.-based nonprofit Climate Resolve, which is working to inform people of ways to adapt to the effects of global warming, said the skiing in local mountains is nothing to write home about. But the proximity to 16 million Southern Californians makes the loss of snow significant.

“No, we don’t have the world’s greatest snow but it is part of our identity,” said Jonathan Parfrey, executive director. “For four or five months out of the year, we can go up into the local mountains and play.”

Besides a lack of snowfall, Hall’s study predicts more rainfall and often in higher volumes.

“We may have the same amount of precipitation but it will come as rain and it will run off immediately. Can we handle those higher cubic feet per second flows?” Parfrey asked.

Since snowmelt is nature’s way of bringing water into natural water conveyances such as rivers and underground aquifers, sudden downpours that carry more mud and silt will test the vulnerability of man-made local reservoirs and dams. “The question is: Can the reservoirs handle the large rainfall events,” Hall said. “A vulnerability assessment needs to be done.”

Water consultant Adan Ortega, managing partner with Water Conservation Partners, said large agencies such as Metropolitan Water District of Southern California, where he worked as vice president of external affairs, have been studying the effects of global warming on water supplies for more than 10 years.

They’re already seeing drops in snowmelt and more frequent droughts.

“It is happening. It has been happening since I became aware, the last 13 years,” Ortega said.

He supports the Bay Delta Conservation Plan and the building of twin concrete channels around the Sacramento-San Joaquin Delta, so more water can move to the farming communities of the Central Valley and urban Southern California and San Diego, he said.

Ortega said water agencies, such as the MWD, the Los Angeles Department of Water and the Los Angeles County Department of Public Works, need to do more reservoir maintenance and treat storm-water runoff which is polluted by street oils and lawn fertilizers. Also, after fall fires, winter rainstorms can tear away at denuded hillsides, sending mud and debris into homes and catch basins.

“It is just a matter of time. So now, we have to figure out a way to pay for all this because it will also be expensive,” Ortega said.

Hall said he hopes his study is used as a primer for helping governments prepare for the effects of global warming in Southern California.

“This is meant to provide practical information. It is not meant to scare people,” Hall said.

Parfrey said the hardest part of his job is getting people and government to prepare for the effects of climate change.

“We are looking at higher temperatures that will have a direct impact on people’s lives,” Parfrey said. “It is our organization’s job to show people how to adapt, to prepare for the future and try to mitigate the impact.”

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