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California's iconic redwoods, sequoias and Joshua trees threatened by climate change

California's redwoods fight to survive
California's redwoods fight to survive 04:18

California's iconic coastal redwoods, some standing since before Julius Caesar ruled Rome, are in a fight for their lives. They are increasingly threatened by wildfires that are larger and more intense due to the impact of human-caused climate change.

And it's not just the redwoods — giant sequoias and Joshua trees are also in trouble. These majestic trees are unique to the West Coast and are an integral part of the fabric of California's storied landscape. But the experts who know and love these trees are genuinely worried about their future.

Last year, 4.2 million acres burned in California's worst fire season on record. Scientists say as the climate warms these fires will grow bigger at an accelerating pace. And although the giant redwoods and sequoias have been historically resilient to natural wildfire, these unnaturally intense fires are starting to overwhelm their defenses, with fires reaching higher up into their crowns.

It is estimated that 10% of the ancient redwoods that burned during the 2020 fire season in places like the Big Basin Redwood State Park, 50 miles south of San Francisco, will die. 

A couple of hundred miles to the east, in the Sierra Nevada mountain range, 350 giant sequoias were killed as flames shot hundreds of feet high, burning far up to the canopy. To the south, in the Mojave Desert, about 1.3 million Joshua trees burned as firenadoes tore through invasive grass.

Joshua trees after fire
Charred Joshua Trees are seen during the Bobcat Fire in Valyermo, California, on September 18, 2020.  KYLE GRILLOT/AFP via Getty Images

CBS News visited Big Basin State Park earlier this month and met with two longtime forest scientists, Todd Keeler-Wolf, a vegetation ecologist, and Joanne Kerbavaz, the senior scientist at Big Basin.

"This fire was on a scale and of an intensity that there are no records of fires that have been that big in this vicinity," Kerbavaz said of the August fire which raged through almost the entire park, engulfing 18,000 acres. 

It started as part of a lightning siege of 14,000 strikes which sparked 350 fires statewide. Lightning events like that are almost unheard of in California; this one was a result of a surge of moisture from a decaying tropical system off of Baja California. 

While that lightning event can be considered just weather chance, it coincided with a sweltering summer heat wave which was undoubtedly made worse by climate change. This heat, on top of a long-term climate-driven drought, dried out vegetation, turning it into a tinderbox just waiting for lightning bolts to spark fires.

In her 22 years at Big Basin, Kerbavaz says she has witnessed a shift: a once nurturing climate has experienced significant change. 

"There's a consensus that things are getting hotter and drier, and most of us who lived in this area can feel that," she said. "And there is a consensus that fog patterns have changed, and that we know that in the redwood forest fog patterns are essential to maintain the redwood forests in this climate." 

She is concerned that in the coming decades, if the fog continues to shrink, the habitat suitable for redwoods that live further away from the ocean will also shrink.  

Big Basin Redwoods State Park, San Jose, California, wildfire.
Big Basin Redwoods State Park in California was hit by a wildfire in August 2020 that burned roughly 97% of the park's 18,224 acres. State Parks safety officer and ranger Gabe McKenna, center, looks at the damage. The park contains 4,400 acre of old-growth redwood forest and 11,3000 acres of secondary growth. Carolyn Cole / Los Angeles Times via Getty Images

Since 2000, the western U.S. has been experiencing a megadrought, one of its worst droughts in 1,200 years. On top of that, since 1970, summers in California have warmed by 2 to 3 degrees Fahrenheit. These types of climate conditions, warmer and drier, set the stage for a longer fire season with larger, more intense fires.

For the redwoods — despite their extensive root system, bark 12 inches thick, and having survived repeated fires over their thousands of years of existence — these recent intense fires are overwhelming their natural defenses. 

Keeler-Wolf has the duty of surveying the wreckage from the August fires. Pointing up at a huge ancient redwood, he talks about the immensity of the fire. 

"It affected the entire tree right up to the very top. This one is a candidate for being pronounced dead, but we haven't pronounced it yet," he said.

Both scientists agree that these coastal redwoods are very resilient. Even when they are heavily damaged from fires, they can re-sprout new trees from their trunks and even their roots.

Kerbavaz explained, "There's also dormant buds by the base that can re-sprout and actually form new trees. Even before the flames were out the plants were starting to come back. Redwoods were re-sprouting at the same time as adjacent areas were still burning." 

Although approximately 1 in 10 of the burned redwoods will not make it, historically speaking, Kerbavaz says 90% should survive. But the loss of so many ancient trees, some of which had been standing for thousands of years, means that things will never look quite the same.

"I am hoping for a long lifetime, but realistically, in the next 40 years it may not look like it looked in the 40 years before. A lot of the trees have been burned. So, we do expect the trees to come back, but in some cases they will look quite different," said Kerbavaz. 

Giant sequoia trees burned
Torched trees smolder in the Alder Creek grove of Giant Sequoia National Monument in Springville, California, on October 28, 2020. The Castle Fire burned through portions of roughly 20 giant sequoia groves on the western slopes of the Sierra, the only place on the planet they naturally grow. Al Seib / Los Angeles Times via Getty Images

Sequoias posses many of the resilient qualities of the redwoods, but unlike the redwoods they cannot re-sprout with ease. That, combined with the fact that they live much further inland, away from the moist marine layer of the Pacific Ocean, makes them even more vulnerable to wildfire.

Park Williams is a Columbia University scientist and expert on the connection between fires and climate change. Through is research, he has observed an unprecedented difference in the climate and its impact on the forests. At a meeting in New York City in mid-January, I asked Park what his research has revealed. 

Jeff Berardelli: It seems to be happening to the Joshua trees, to the sequoias and to the redwoods. And those are all different microclimates. So what is going on?

Park Williams: Well, there are a lot of things going on, but the one thing that all forests across the western U.S. are experiencing is warming. And so as we warm up the atmosphere, these forests are more likely to burn.

Jeff Berardelli: These fires are able to burn higher up on these trees, causing these trees to die where they wouldn't have died years ago. Is that right?

Park Williams: We know that fires were very common in these forests over the last millennia. These trees are designed to be able to tolerate fire, but they can only tolerate fire if these fires aren't giant catastrophic events. These giant fires with flames that are hundreds of feet tall managed to kill many hundreds of these ancient majestic trees.

As giant as these fires are, Williams says this may be just the beginning. As the region continues to warm, wildfires will get worse at an accelerating pace.

"The really important connection between heat and fire is it's actually exponential. And that means that for every degree of warming that you have in California, the amount of extra forest fire you get goes up more than it did in the previous degree of warming."

All of the scientists interviewed for this story agree that if we don't stop warming the planet, these majestic trees will be facing a losing battle. 

"We do fear that there might be some thresholds that are crossed. So that some of the species, some of the things that live here, will no longer be able to be sustained," said Kerbavaz.

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