UCLA scientists discuss factors of intense fires across Los Angeles County
As flares spread across Los Angeles County, researchers seek to uncover the science behind what fuels the flames. The first of the fires started in Pacific Palisades on Jan. 7 and has since burned over 23,000 acres, according to the Cal Fire website. There are three active wildfires in LA County, but no evacuation warnings or orders cover the UCLA campus as of 4:15 p.m. Tuesday.
Although the cause of the fires are unconfirmed, the Santa Ana winds and hydroclimatic factors have contributed to their rapid spread and destruction, said Yue Li, an assistant professor of geography.
Mitch Hung, a doctoral student in physical geography, said for a wildfire to occur, there must be both an ignition source and a spreader. He added that the Santa Ana winds acted as both an ignition source by stripping moisture off of vegetation and as a spreader with high-speed winds carrying embers over long distances.
“All of the vegetation that grew in the first half of the year just got completely dried out, so you have a sort of abundance of fuel,” Hung said. “That basically set the stage for really extreme fires like this to happen.”
The lack of rainfall in Southern California over the last few months also contributed to a perfect storm of dried out vegetation, relatively warm weather and intense wind, said Glen MacDonald, a distinguished professor of geography and ecology and evolutionary biology.
Cycles of dry weather followed by rain both grew and dried vegetation, MacDonald said. The dry vegetation was easily ignited by the Santa Ana winds, he added.
“The ignition source was in the wrong place at exactly the wrong time, and once that got going under those conditions, fire suppression became, as we saw, pretty much impossible,” MacDonald said.
Recent UCLA research has shown that vapor pressure deficit – a measure of how much water the atmosphere will suck from a specific land’s vegetation – is an important variable in wildfire spread, Hung said. One of Hung’s research colleagues was able to demonstrate that an increase in that deficit indicated more intense fires, but not necessarily more frequent fires, he said.
Hung also said wildfires have a significant effect on air quality.
“They’re extremely dangerous to breathe, in many cases, and they increase respiratory stresses or can induce respiratory illness,” Hung said.
Li said satellite data over the last 20 years has indicated that there has been a global decline in wildfires. Despite this, there has been an increase in wildfires in the western part of the United States – including California – over this same time period, he said.
California wildfires have served as a major indicator of global climate change, Li said. He added that through his research, he learned that tropical ecosystems potentially have the ability to suppress the wildfires.
Although there will be allegations and blame for the fires, MacDonald said he urges everyone to instead focus on developing solutions that promote fire safety.
“The pressure will be on to rebuild quickly, and if we could take a breath and rebuild quickly, but also rebuild smart … to build fire resilience, because we’re not going to get fire out of the equation in Southern California,” MacDonald added.
Southern California will undoubtedly have more of these events, as its natural environment is dry and fire-prone, MacDonald said. However, residents will hopefully be better prepared for future incidents and will not have as much structural loss, he said.
Hung said LA County should expect an increase in both the size and intensity of wildfires throughout the next decade as these wildfires also serve as a manifestation of larger climate change trends.
Changes to the LA landscape due to increased urbanization and the natural environments of neighborhoods, like that of Pacific Palisades, have made these areas more vulnerable to wildfires, MacDonald said.
However, once there is precipitation, some of the grasslands and shrubs that are in the Pacific Palisades area will grow back because of increased soil nutrient levels caused by these fires or the plant’s ability to adapt to fire, such as that of chaparral and coastal sage scrub, MacDonald added.
Li said the technology behind resources, such as the California Department of Forestry and Fire Protection, or Cal Fire website, uses geographic information systems – techniques undergraduate students can learn. However, he added that there are still some questions to be answered in terms of technological improvements.
Climate, physical and environmental research at UCLA will be impacted by the fires as well, Li said. He added that he also hopes that this research is better integrated into policy and public issues.
“I can’t help thinking about what is the next step of my research,” Li said. “A major priority of our work is trying to quantify the wildfire behaviors in response to climate change and also human land use.”
