In Los Angeles, a barrage of intense rainstorms has spurred landslides and exacerbated coastal erosion in California, leading to precarious situations for multimillion-dollar homes perched on cliff edges. The storms have caused hundred-foot palm trees to tumble into the sea and prompted the closure of a historic chapel.

While the state is currently experiencing a drying-out period, the repercussions from this season's extreme rainfall could reverberate for years to come. Climate change, with its amplification of rainfall rates, acceleration of sea level rise, and exacerbation of drought severity, is a significant factor in the ongoing transformation of California's landscape.

This season's storms have provided Californians with a stark glimpse into the consequences of a warming planet, as gradual processes that scientists have long warned about unfold before their eyes. Geologist Mike Phipps, from the geotechnical engineering firm Cotton, Shires, and Associates, emphasized the combined risks of landslides and sea level rise in reshaping the California coastline.

"The coastline is facing considerable risk," he noted. "As cliffs erode, buildings are increasingly threatened, leading to instances where structures have been demolished and others teeter perilously close to the ocean."

Two years ago, the entire state was engulfed in drought, desperately craving rainfall, as reported by the National Drought Monitor. Fast forward to the present, and only small pockets, totaling 7% of the state, are categorized as "abnormally dry," while residents now find themselves pleading for respite from relentless downpours.

The turning point came last winter when over a dozen atmospheric rivers unleashed precipitation upon the state, alleviating the drought and saturating California's hillsides with moisture.

This year, the cycle of extremes persists. In downtown Los Angeles alone, this month's rainfall has surpassed 12.5 inches, quadrupling its typical monthly average and nearly doubling the total rainfall of 2022, according to National Weather Service data. The deluge has pushed certain slopes perilously close to the edge, heightening the risk of landslides.

During the latest storm, the city of Los Angeles reported 63 incidents of debris flows or mudslides. Following a more severe storm earlier in the month, the city received service calls for 592 mudslides, resulting in at least 16 buildings being "red-tagged," prohibiting entry due to safety concerns.

Nate Onderdonk, a professor and geomorphologist at California State University Long Beach, explained, "When you have this continuous onslaught of storms, water accumulates in the slopes, significantly increasing the likelihood of landslides."

In the Rancho Palos Verdes community, a coastal city in Los Angeles County known for its susceptibility to landslides, recent rains have accelerated land movement and caused shifts in areas not previously mapped for slides, as stated in a city news release.

Nate Onderdonk explained that layers of sedimentary rock in the region tilt toward the sea. When weak clay layers become saturated with water, they expand and often slide due to minimal friction.

The ongoing intense rainfall season has heightened concerns and expanded the areas at risk. Geologists had developed a plan decades ago to dewater slopes in the Abalone Cove landslide area, significantly slowing movement. However, recent acceleration in movement led to the closure of the Wayfarers Chapel, a national historic landmark designed by Frank Lloyd Wright Jr., in Abalone Cove about a week ago.

"This is an area that had apparently been stabilized," noted Onderdonk. Faced with the threat to homes and roads, the city of Rancho Palos Verdes has requested Governor Gavin Newsom to pursue state and federal emergency declarations, potentially expediting emergency repairs through streamlined permitting processes.

The landslide risk is a significant concern for numerous coastal cities along the California coast.

This week, houses in Dana Point grabbed headlines after The Los Angeles Times and other media outlets published drone footage revealing several large seaside residences perched precariously above landslide debris.

Scientists continue to investigate how climate change will impact the frequency and severity of landslides. A 2022 study published in the peer-reviewed journal Geophysical Research Letters discovered that landslides are highly sensitive to climate changes, moving significantly faster during wet years compared to dry years.

Additionally, a 2019 study published in the Bulletin of the American Meteorological Society found that landslides often coincide with atmospheric river storms approximately 76% of the time in the San Francisco Bay area. Scientists attribute the increasing frequency and intensity of atmospheric river storms on the West Coast to a warmer atmosphere's ability to absorb and transport more water vapor.

California's bluffs face multiple challenges beyond gravity. Rising sea levels and more intense storms are eroding the state's beaches and shoreline, a phenomenon climate scientists have long warned about. According to a United States Geological Survey report, Southern California could lose up to two-thirds of its beaches by 2100 due to rising sea levels caused by climate change.

Global warming, primarily driven by human use of fossil fuels, is the leading cause of sea level rise. Melting glaciers and polar ice sheets contribute to rising sea levels, while warmer ocean water expands in volume.

This dynamic has left many residents and observers witnessing the gradual shrinkage of their beloved beaches.

Edward and Debbie Winston-Levin, homeowners residing in Dana Point, California, overlooking Capistrano Beach, have witnessed the gradual erosion of the coastline over time.

Edward Winston-Levin, 77, recalled, "There used to be a volleyball court and a basketball court down there that all have been eroded. And on a high-surf day, it covers the parking lot." They express concern that their property, situated on a steep slope, could eventually succumb to a landslide and slide into the sea.

"If one slide starts, it’s going to go on, we’re going to lose our houses with, you know, beautiful views," he lamented.

In response to these challenges, many coastal cities are implementing drastic measures to adapt. In Del Mar, plans are in motion to relocate train tracks deemed too close to the coast. Similarly, in San Clemente, the state is preparing to construct a $7.2 million wall to reinforce a landslide area, aiming to stabilize a slipping hillside that has disrupted train services through Orange County.

Near UC Santa Barbara in Isla Vista, a collapsing cliff prompted student evacuations, leading to the reconstruction of several buildings further inland.

Experts acknowledge that this evolving landscape presents a dilemma: should the state prioritize preserving its iconic beaches or fortifying cliffside homes?

"That's a very complex question," noted Phipps. "Obviously, Californians love their beaches, and everyone's going to want to keep their beaches. However, in many areas, beaches are narrowing and disappearing."