Climatologists, oceanographers and meteorologists gathered this month at the Scripps Institution of Oceanography in La Jolla, just steps from the Pacific Ocean, to discuss what the region can expect from the worst El Niño on record.
The University of California San Diego hosted the event to sound the alarm, once again, about weather conditions that are warming ocean waters, raising sea levels and causing devastating rains that worsen coastal erosion.
El Niño is a natural phenomenon that repeats every few years. Powerful trade winds push warmer-than-normal currents from the Pacific Ocean toward the California coast. This year’s event is shaping up to be one of the largest ever documented.
Even though the outlook is dire in many ways, scientists say, there could still be weeks of sunshine in the months to come. There is no way to know for sure whether this season’s precipitation will be beneficial or tragic.
“El Niño is just setting the stage and tipping the scales toward more extreme weather,” said Julie Kalansky, a climatologist at Scripps.
The atmospheric jet stream generally becomes stronger during an El Niño. That increases the chance of what’s called an “atmospheric river” capable of fueling storms and lasting for days, carrying up to five times the amount of water in the Mississippi River, she said.
Moderate precipitation could be beneficial if it removes wildfire risks, fills reservoirs and strengthens the state’s mountain snowpack. However, excessive rain causes erosion, flooding and disasters along streams, rivers and on California’s fragile coastline.
“We don’t yet know how El Niño will affect precipitation,” Kalansky said.
A long-range forecast from the National Weather Service projects a maximum of 10 days into the future, with a low probability for events that far away, said Sebastian Westerink, a meteorologist at the Weather Service office in San Diego.
The chances of getting a more accurate forecast improve if you look five to seven days ahead and are best within three or four days of an expected weather event, he said.
Factors such as soil saturation from previous rains are also considered before the weather service issues flood warnings and other notifications, Westerink said. A downpour on wet soil increases the risk of flooding and erosion.
Warming waters
Scientists have several ways to measure ocean temperatures, and almost all of the data discussed show temperatures well above normal.
One of the oldest records comes from the Coastal Station Program, which has been measuring temperatures by hand since 1916 using a thermometer lowered from the end of the Scripps Pier in La Jolla.
“Over the last 10 years, we’ve seen the highest temperatures ever recorded in 10 years (over the 110 years of the program),” said Melissa Carter, an oceanographer at Scripps.
On October 8, the surface water temperature at the pier was 73.6 degrees, which tied a previous record for that date. The average temperature for October 8 is 66.3 degrees, based on 107 samples collected since 1917, according to the Scripps website. The minimum for this date was 60.6 degrees in 1980.
By Tuesday, October 13, the surface temperature had dropped to 70.9 degrees, still in the top 10% ever recorded on that date. The record high for October 15 was 75.7 degrees in 2015. The average for this date is 64.7 degrees.
Scripps Pier recorded 51 days this year with record surface water temperatures as of Oct. 13, the website says.
Warmer water reduces chlorophyll and phytoplankton in the ocean, creating a shortage of food for birds and marine life, Carter said. Higher temperatures also slow the growth of giant kelp, which has evolved to thrive in a colder, nutrient-rich environment and is home to many marine species.
In addition, fish, birds and marine mammals, such as the olive ridley sea turtle, which normally live in more tropical waters to the south, are increasingly numerous along the California coast.
Scientists have also been using a global system of solo floats called Argo to collect data on ocean temperatures for about two decades now. The floats show increasing temperatures in recent months, on top of what was already considered “a marine heat wave,” said Daniel Rudnick, a physical oceanographer at Scripps.
“Warmer water takes up more volume, so sea level is higher,” Rudnick said.
Climatologists say the warmer water could raise sea levels by 6 to 12 inches. This can become a major concern when combined with the highest tides of the year, known as king tides, which occur a few days per month each winter.
This year’s spring tides will peak around October 27, November 24, December 24 and January 22.
Erosion
Coastal flooding usually occurs during high tides. If a powerful local storm or large swell from a distant storm arrives at the same time, erosion and flooding are almost certain.
“These (tides) really increase the risk of damage along our coastline,” said Adam Young, a coastal geomorphologist with the Scripps Coastal Processes Group. “It has a real impact on the region as a whole.”
The San Diego County coastline has a number of vulnerable areas. Waves often crash onto oceanfront streets, like The Strand in Oceanside, sending cobblestones onto the sidewalk and seawater into garages.
In Carlsbad, high tides sometimes force the closure of the southbound low-lying lanes of Carlsbad Boulevard, also known as Highway 101, at the Encinas Creek exit. Last month, the city declared a local emergency to speed repairs after new erosion threatened to undermine the highway at a location just north of the creek and south of Palomar Airport Road.
In recent weeks, the northern portion of Carlsbad State Beach, between Tamarack and Pine avenues, has seen some of the worst erosion in memory for most residents. The Tamarack Avenue parking lot has been closed to vehicles since Labor Day weekend due to asphalt damage.
A state official said last week that plans were underway to repair the parking lot and should be completed by the end of the year.
Most San Diego County beaches have lost sand to prevailing ocean currents during the summer, although this is generally a natural rebuilding season in the cyclical life of the shoreline.
Clifftop homes in Encinitas and Solana Beach have been fighting erosion for years by adding, expanding or rebuilding seawalls. This winter’s storms, if they conform to forecasts, could bring new dangers to these properties.
King tides flooded buildings along and near Bayside Walk in Mission Beach in July this year, an inconvenience usually more likely to occur in December and January.
Coastal cities from Oceanside to San Diego have created teams of city workers to review their flood response procedures and begin cleaning storm drains and streams in preparation for the expected El Niño.
A section of San Diego’s only rail link to Los Angeles and the rest of the United States is also threatened by the prospect of rising waters.
About 1.7 miles of the trail run along a high oceanfront bluff in Del Mar. Transit agencies and regional planners have been installing seawalls, retaining walls, pilings and other measures for decades to stabilize the steep oceanside slopes.
However, a single landslide could stop all passenger and freight trains entering and leaving San Diego until emergency repairs are completed.
The segment is part of what is known as the Los Angeles-San Diego-San Luis Obispo (LOSSAN) rail corridor which covers 351 miles between San Diego and San Luis Obispo. One of the busiest routes in the country, it carries daily Amtrack passenger trains and Coaster commuter trains, as well as overnight BNSF freight trains that transport thousands of new cars and other valuable commodities between the Port of San Diego and Los Angeles.
Another hot spot on the rail corridor is in San Clemente, Orange County, just north of Camp Pendleton. About seven miles of railroad tracks in southern Orange County run along the beach, low enough that waves crash over the tracks at high tide in some places.
Several times this year, strong waves have short-circuited rail communications systems and eroded some of the gravel ballast under the tracks near the San Clemente Pier, delaying or stopping some trains.
Long-range plans call for moving the two railroad hotspots inland, likely to a new route near Interstate 5. However, that unfunded solution would cost billions of dollars with poor prospects for that much in state or federal grants.
Planners have said a new route through a tunnel in Del Mar could be completed by 2035, but that goal may be optimistic and a solution for San Clemente is much further into the future.
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