The famous Muir Woods is one of the last old-growth coastal forests on the planet, and certainly the only one in the Bay Area, which is why every year around 1 million people visit northern California to gape in wonder at the gigantic redwoods.

One redwood in particular, Tree 76, a behemoth that stands 249 feet tall (that’s only 51 feet shy of the length of a football field), was thought to be roughly 1,500 years old. Now, thanks to tree-ring analysis, a researcher at Humboldt State University has discovered the tree is nearly half that age, clocking in at just 777.

Despite its incredible size, that puts Tree 76 at just above normal when it comes to age — the average redwood tree being between 500 and 700 years old. The real great-grandparents of the old-growth forests can live for more than 2,000 years.

The new study from biologist Allyson Carroll, a tree-ring specialist, done in partnership with the Save the Redwoods League, is the most comprehensive tree-ring record ever collected. It looks into the age and history of trees in the Muir Woods. By extracting multiple pencil-thin sections of the tree and contrasting them with other trees, scientists were able to get conclusive information, with about a 34-year margin for error, on the age of Tree 76.

Age isn’t the only information the rings provide. Researchers can even determine specific dates by looking at the size and thickness of the rings of the tree. Rings are larger during wet years and are narrower when the climate is dryer.

The scientists’ endgame isn’t just to find out how old trees are, although that information alone has turned out to be illuminating. By studying the tree-ring patterns and seeing how the trees grow during various points throughout its history, the researchers hope to discover how the redwoods react to climate change.

Carroll told the SFGate that the collective redwood tree-ring record can give them accurate weather information dating back to the year 328, providing data on drought years, fire and flooding. In addition to finding out weather patterns, researchers have also learned that over the past few decades, redwoods have been growing faster.

Save the Redwoods League explains on its website, “Now, through stable isotope analysis, our scientists are uncovering the climate history recorded in redwood tree rings. Water sources leave a stable isotope imprint in the cellulose of wood produced annually. These analyses will help us learn more about how redwoods grew over the last millennia and how the climate changed.”

In addition, they believe, “the results will help us make informed decisions about how to protect and restore redwood forests as they face rapid climate change.”

As famous naturalist John Muir said upon learning that William and Elizabeth Kent were naming a redwood forest in northern California in his honor, "This is the best tree-lovers monument that could possibly be found in all the forests of the world."

Perhaps with the information provided by this research, it will remain so.

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