Extreme Temperature Diary- Wednesday March 10th, 2021/ Main Topic: One Of The First Casualties Of Climate Change…California’s Coastal Highway Is Falling Into The Sea

The main purpose of this ongoing blog will be to track planetary extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: One Of The First Casualties Of Climate Change
California’s Coastal Highway Is Falling Into The Sea

Dear Diary. Over the last 100 years many a Hollywood movie and television program has been made featuring a few scenes of California’s winding Highway 1, which runs right along most of that state’s coast. It’s no wonder. The route runs along some of the most beautiful scenery in the nation. Now it is a shame that the road is threatened either by increasing wildfires or erosion, causing some sections to fall into the Pacific, making the route as a whole impassable. Gone are the days in which you could take a few days on a leisurely trip to travel the entire route, which starts north of San Francisco and runs through the Los Angeles area.

USA Today has written a detailed report on what has happened to Highway 1, which I will share for our main topic on this Wednesday:


California’s Pacific Coast Highway is falling into the ocean. Is this the end of the road for one of America’s most scenic drives?

Joel Shannon Doyle Rice USA TODAY

Published March 2nd, 2021

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. Most recently, 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.

(Big Sur, California…Getty Images)

California’s fragile wonder is ‘one of the most scenic drives in the nation’

The journey is the destination on California’s Highway 1.

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 that 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.

“That’s what makes it iconic,” she said. It’s “one of the most scenic drives in the nation.”

The highway climbs from sea level to hundreds of feet above the ocean, wrapping around the terrain to give drivers glorious views – and pull-offs to safely enjoy them.

Given the road’s location, it is no surprise that Highway 1 is frequently damaged.

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.  

Construction crews work on a section of Highway 1 which collapsed into the Pacific Ocean near Big Sur, Calif., on Jan. 31.

Construction crews work on a section of Highway 1 which collapse on January 31st near Big Sur.

Effects of climate change endanger future of Pacific Coast Highway

Although the highway is celebrated for its ocean views, it is not rising seas that worry Griggs the most. It’s fires and rain.

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.

In fact, 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.

One well-known nickname for an atmospheric river is the “Pineapple Express,” which occurs when the source of the moisture is near Hawaii. 

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.

Waves crash on the shore on May 24, 2017, after a massive landslide that went into the Pacific Ocean in Big Sur, Calif. The slide buried a portion of the Pacific Coast Highway under a 40-foot layer of rock and dirt and changed the coastline below.

Waves crash on the shore after a massive landslide on May 24th, 2017. Image Credit John Johnston (of San Luis Obispo) Via AP

What’s around the bend? California Coastal Commission expects adaptations

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 two-lane 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 non-motorized vehicles.

Ewing expects more solutions like that one will be needed in coming years and decades.

“You can keep putting these Band-Aids on it,” Griggs said, noting that adaptations are especially challenging in the unforgiving terrain of Big Sur. Simply retreating the highway inland slightly isn’t an easy proposition.

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.”

Contributing: The Associated Press

More Photos:



Here is an “ET” reported from the Plains on Wednesday:

Here is some more February 2021 climatology:

Here is more climate and weather news from Wednesday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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