Global warming seems to suit redwoods, at least for now, study shows
SAN JOSE, Calif. — Climate change is melting glaciers, worsening droughts and raising sea levels around the world.
Scientists worried that ancient redwood trees on the U.S. West Coast might also be at risk as the planet heats up. But new research shows global warming may actually be helping. At least it is for now.
“We’re not seeing any evidence of declining growth rates,” said Steve Sillett a nationally known redwoods expert. Some places are actually seeing more growth, he said.
The trees may prefer warmer temperatures. They may benefit from more sunlight or a longer growing season. Many years of work to limit forest fires may also be helping. Or the trees might even like the higher levels of carbon dioxide in the atmosphere.
Nobody knows yet.
"An Incredibly Hopeful Story"
Sillett and other researchers are working on a four-year study. They found that coastal redwoods and giant sequoia trees in California’s forests grew more in the 20th century. This happened while polar bears, coral reefs and other parts of the Earth's environment suffered from climate change.
Redwood forests near the California-Oregon border have grown the most. Conservationists are happy about the news. But they are cautious.
“Redwoods are an incredibly hopeful story in the midst of seemingly catastrophic environmental change around us,” said Emily Burns. She is science director for Save the Redwoods League. The nonprofit group is paying for the research. “They are growing vigorously.”
Still, scientists continue to be worried about water.
A study published three years ago found that the amount of fog in redwood areas along California’s coast has fallen 33 percent over the past century. Fog is made of water droplets. But so far the lack of fog may have been a good thing. It may have allowed more sunlight to reach the trees, said scientist Todd Dawson.
The scientists also looked at giant sequoias. They live in the Sierra Nevada mountains and are cousins of the redwoods. Warmer weather may have increased their growing season by reducing the number of days they are under snow.
Good News, But For How Long?
The news is good now. But some scientists working on the project worry that conditions could worsen for the trees if rising temperatures lead to less rain and snow in California.
“There’s a tipping point,” Dawson said. The growth increase probably will end as it gets warmer and drier. One thing that will happen is there will be less densely packed snow. That means less water for giant sequoias, he pointed out.
The researchers do their work in the world’s tallest and largest trees. They have climbed dozens of giant redwoods and sequoias as part of the $2.5 million project.
Many of the trees were growing before Europe’s oldest churches were built. The scientists fitted trees with sensors to measure temperature, rain, fog and other weather conditions. They used lasers to help measure the heights of trees. They conducted studies to re-create weather from centuries ago. They took core samples to learn how old the trees were and how fast they were growing.
Sillett discovered the oldest known coast redwood tree in existence during this research. The tree in northern California is at least 2,520 years old. “We were way off the trail,” Sillett said. “We stumbled upon this tree. I was like, ‘Oh my God, this tree is big.’ It looked old.”
The tree is nearly 300 feet tall. Yet it is still significantly shorter than the world’s tallest tree. A 379-foot-tall redwood called “Hyperion” was discovered in 2006 in a remote corner of Redwood National Park.
Around Since The Dinosaurs
Redwoods have been around for 120 million years or more. They once lived side by side with dinosaurs, across Canada, Utah, Montana and Southern California. Today, coast redwoods exist only along a narrow band from central California to the Oregon border. Giant sequoias live only in the Sierra Nevada mountains.
There is cause for concern.
There is a lot more carbon dioxide in the air now than in the mid-1800s. It comes from burning fossil fuels like oil, coal and natural gas. Some scientists say if things keep going like this, redwoods will not be able to live in parts of California by 2100.
“Redwoods define our state. They define us and our sense of place,” Dawson said. “Why should we preserve them? Why would you preserve a Mozart concerto? They add value to the human condition.”