Los Angeles could lose 40 percent of its snowfall by the middle of this century to climate change, predicts a new study from researchers at UCLA.
Lead researcher Alex Hall and his team used global climate models to project dramatic drops in snowfall in the region’s low-elevation mountains within 30 years – whether humans cut carbon emissions significantly or not.
In a scenario where global carbon emissions slow, the study predicts snowfall at 69% of present rates by the mid-21st Century.
If anthropomorphic contributions to greenhouse gases continue unchecked, snowfall will drop to 58% of present rates. “Areas of particularly noticeable loss [of snow] include the northern hills of the San Gabriel Mountains and the areas between the San Gabriel and Tehachapi Mountains,” write the authors.
UCLA researcher Alex Hall says the numbers are a bit "fuzzy" - that is, different global climate models predict slightly diverse outcomes - but added together, they paint a picture of significant loss of snow in southern California.
"That loss may not be quite as great as the most likely estimate, or it might be quite a bit greater, but there definitely will be some kind of a loss, and it will probably be pretty significant," he says.
The study is the second in which the UCLA team relies on complex calculations to forecast the impact of climate change on LA’s geography with deep precision. Meandering and jagged coastlines, mountains and canyons are represented in the analysis. By looking more closely at “micro” climate zones, researchers say they can create more accurate and more useful predictions on which southern Californians can rely.
"Anyone who has explored the landscape in the Los Angeles region can tell you there’s a lot of climate variety here," says Hall. "The goal is to take into account all of that complexity and make a comprehensive assessment of climate change."
For southern California mountain areas, winter’s snow sports bring tourists, money and jobs.
"It’s really great to hear about the study, because it’s just another tool that we can have to raise awareness of climate change when it comes to winter sports and recreation,” says Chris Steinkamp, with the group Protect Our Winters, which lobbies Congress on behalf of snow sport enthusiasts to take action on climate change.
Steinkamp says UCLA’s study demonstrates how vulnerable resort towns like Big Bear are. “We work with a lot of professional athletes that ride up there, and we have friends that work in restaurants and small businesses up there,” Steinkamp says. “So when it doesn’t snow, those jobs are at stake. And it’s a really terrible situation in terms of the economy up there.”
Snowpack also melts into streams and rivers and becomes water supply.
Celeste Cantu of the Santa Ana Watershed Project Authority says UCLA’s snowfall study confirms the authority’s own predictions about precipitation. Relying on this research, Cantu says, southern California’s water managers can adapt the ways they store rain and snowmelt.
“So we are looking at, how do we operate differently to respond to that changed dynamic?” Cantu says. “And we can do it.”
UCLA’s study does offer some enticement for cutting carbon. It suggests that by century’s end, slowing human contributions to global warming would keep more snow on the mountain longer. In contrast, business as usual could push snowpack down to a third what it is now within 100 years.
Alex Hall emphasizes that he and the other authors make no policy recommendations in the new study. "It’s meant to be empowering," Hall says. "It’s putting the decision-making ability into the hands of the people of Los Angeles. It’s giving them the information they need to make informed decisions."