California redwoods are tops in carbon storage needed to fight climate change, nonprofit says

Steadfast and silent, defying age and decay, California’s redwood trees have survived since the time of the Roman Empire and offer solace to people in an increasingly unrecognizable modern world.

Standing as tall as 30-story buildings and cloaked in furrowed ruddy bark shielding them from fire, insects and disease, the giants that live nowhere else on Earth offer a buffer against the global threat of climate change.

Throughout their lives, the world’s tallest trees - Sequoia sempervirens, meaning “always flourishing” - absorb carbon dioxide, the most prolific heat-trapping gas, and permanently lock it up in their durable heartwood.

Coast redwoods are “a critical ingredient in the fight against climate change,” said Sam Hodder, president and CEO of Save the Redwoods League, the San Francisco-based nonprofit that has protected more than 216,000 acres of redwoods.

Old-growth redwood forests store more carbon - up to 890 metric tons per acre - than any other forest type in the world, with about triple the capacity of tropical rain forests, according to a study announced by the league last week.

Some second-growth redwood forests on land logged in the mid-1800s had accumulated as much as 339 metric tons of carbon per acre, said a study last year that was also a product of the 11-year research partnership between the league and Humboldt State University.

Put together, the studies show that super-aged redwoods can “maintain high levels of productivity for well over 1,000 years,” said Steve Sillett, a Humboldt State professor and lead author of the studies.

“Just as exciting is the fact that young redwood forests can accumulate biomass at rates even faster than old-growth stands - with trees surpassing 200 feet tall in less than a century,” he said in a statement.

The distinction is important because California has left only 113,000 acres of old-growth redwoods, mostly protected in parks and preserves and representing just 5% of the ancient forest that existed prior to the Gold Rush.

The 102-year-old league’s concern focuses on the 1.5 million acres of second-growth redwoods, with all but about 400,000 acres privately owned and subject to commercial harvest.

In Sonoma County, logging the redwood giants along the Russian River began as early as 1836. Today there are only 143,377 acres of redwoods, including 9,037 acres of old-growth trees, most of them located on private property.

In 2018, the league acquired a 730-acre forest north of Cazadero, home to more than 300 old-growth redwoods over 250 feet, and a somewhat shorter one at 239 feet that is the county’s oldest at 1,640 years and broadest at 19 feet in diameter, as wide as a two-lane country road.

Recognizing redwoods as “our allies in the fight against climate,” Hodder said, “gives us all the more reason to accelerate the pace and scale of our efforts to protect and restore young, recovering forests and set them on course to become the old-growth forests of the future.”

Sillett, who pioneered techniques for scaling the giant trees and studying the ecosystems in their expansive canopies, said setting second-growth forests “on the trajectory to old-growth characteristics would have tangible carbon benefits.”

The collaborators are by no means the first to see forest health as an antidote for global warming.

The United Nations Intergovernmental Panel on Climate Change last year issued a report on the outsized role forest conservation can play in addressing climate change.

The Conservation Fund, a Virginia-based nonprofit, began buying second-growth redwood forests in Sonoma and Mendocino counties in 2004 with an eye on capturing carbon.

Young, fast-growing trees are “a carbon sponge, they soak it up,” said Chris Kelly, the fund’s California project director.

The fund now owns 74,000 acres of land and last year gained just over 7 metric tons of carbon per forested acre, totaling about 485,000 metric tons.

In 2016, Kelly said he expected the trees to absorb about 175,000 metric tons of carbon a year.

Having spent $120 million on land acquisition - including the 19,645-acre Preservation Ranch in northwestern Sonoma County, renamed Buckeye Forest - The Conservation Fund has since earned $50 million from selling carbon credits to major polluters required by law to offset their greenhouse gas emissions, Kelly said.

The fund is also selectively thinning the redwood forests, generating revenue from timber sales while also improving productivity, he said.

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.