Iconic Highway 1 pushed to the edge
Climate change threatens legendary California road
Soaring mountains on one side of the road and the Pacific Ocean on the other: It was 1956, and Gary Griggs was experiencing California State Route 1 for the first time.
He was a child, but in the following decades he would drive this scenic stretch of road, called the Pacific Coast Highway, dozens of times. He also would learn how fragile it is.
In 2017, Griggs consulted on a major repair to the highway as an erosion expert. Now, he says, the iconic road’s days may be numbered – at least in its current form. Future generations may say “it was great while it lasted,” the University of California, Santa Cruz professor predicted.
Frequent damage has long plagued the PCH. In January, yet another chunk fell into the ocean after intense rainstorms, which created a debris flow that overwhelmed water drains more than 100 miles south of San Francisco.
This time, a 150-foot piece of road broke off, the state Department of Transportation said. Repairs are scheduled to be complete in early summer. For now, travelers must turn around when they reach the gaping hole – there’s no bypass in that remote stretch of road.
As global temperatures warm because of human-caused climate change, Griggs said, the conditions that lead to this kind of damage will only increase. Griggs said it’s “inevitable” that one day the fixes and repairs won’t be enough, or will be too costly to save the highway.
California’s fragile wonder
The two-lane road hugs the California coast for hundreds of miles. In its most famous stretch between San Francisco and Los Angeles, the roadway is carved into steep, mountainous terrain around the rugged Big Sur coast.
Griggs calls the region a “geological nightmare” – a mix of hard and soft rock makes development a challenge at best. It’s also at the edge of two tectonic plates.
That’s part of the reason it has remained a relatively rural stretch of road with few of the tourist attractions you might expect from a world-renowned destination.
“There are easier ways to go north or south, but there aren’t any more beautiful ways to do it,” said Lesley Ewing, a coastal engineer with the California Coastal Commission.
There are no strip malls and few gas stations, said Paula Twidale, senior vice president of Travel for AAA.
Effects of climate change
For decades, the highway has struggled to make it through a calendar year without an incident that closes a portion, Ewing said.
That’s to be expected from a “highway at the edge of the continent,” said Kevin Drabinski, a Caltrans spokesperson in California’s Central Coast.
Usually, damage occurs because of a combination of weather and geological activity, Drabinski said.
But what is changing: the frequency and severity of that damage.
Experts hesitate to attribute an individual incident of road damage directly to climate change. But the effects of climate change are creating conditions that worsen Highway 1’s existing problems.
Wildfires are increasingly dotting California with massive burn scars: scorched earth with little vegetation to help hold the soil together.
Overall, in 2020, nearly 10,000 fires burned more than 4.2 million acres in California, more than 4% of the state’s roughly 100 million acres of land. That made 2020 the largest wildfire season recorded in California’s modern history, according to CalFire.
A burn scar in steep terrain, like that found in Big Sur, creates perfect conditions for mudslides and debris flows.
All that’s needed is a deluge of rain – which, in coastal California, is also happening increasingly frequently.
The types of big storms that can batter California with heavy rain and snow are projected to increase in intensity in coming years because of climate change, said UCLA climate scientist Daniel Swain.
“There’s a lot of evidence that atmospheric rivers will become more intense as the climate warms,” Swain said. While we may not see more atmospheric rivers overall, the ones that cause problems will become stronger, and there will be more major storms, he said.
Made visible by clouds, the ribbons of water vapor known as atmospheric rivers extend thousands of miles from the tropics to the western U.S. They provide the fuel for the massive rain, snowstorms and subsequent floods along the West Coast.
These “rivers in the sky” are responsible for up to 65% of the western USA’s extreme rain and snow events, a 2017 study said. Though beneficial for water supplies, these events can wreak havoc on travel, trigger deadly mudslides and cause catastrophic damage to life and property, the National Oceanic and Atmospheric Administration said.
Swain said the powerful atmospheric river storms have historically caused problems with the Pacific Coast Highway, which “is not in a very geologically stable position even in the best of times.”
Most of the land slippages along the highway are caused by land on the upper, mountainous side of the highway – such as during landslides, mudslides and debris flows – which are often worsened by California’s ferocious wildfires, he said.
Swain said climate change is expected to worsen both the frequency and potency of wildfires in California, adding yet another layer of concern for vulnerable Highway 1.
What’s around the bend?
California has been planning for Highway 1’s future for years, and the state’s Coastal Commission has been charged with protecting the highway, Ewing said.
Californians should expect a twolane road will continue to span most of the state’s coastline. Studies and plans have been made to ensure the highway continues to function.
But adaptations will need to be made. South of San Francisco, a section of Highway 1 plagued by rockslides was covered by a tunnel in a project that cost hundreds of millions of dollars, the Metropolitan Transportation Commission said in 2013.
Breathtaking views are still available in a milelong section for pedestrians and nonmotorized vehicles.
Ewing expects more solutions like that one will be needed in coming years and decades.
Some repairs made to the Highway 1 are now made to last for decades in anticipation that damage will continue, Caltrans’ Drabinski said.
It will take “innovative designs” to protect the road, he said. For now, travelers can expect that “the general experience of that road will still be there.”