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A Foggy Situation

If you want to see what may be the tallest natural creation on the planet, get ready to flex your splenius capitis, because you’ll have to bend your head way back to see to the very top of the Hyperion tree. The giant Redwood climbs 379.3 feet into the atmosphere and now holds the record for the world’s tallest living tree. It resides in California’s Redwood National and State Parks, where it bumps elbows with many other Redwoods more than 200- and 300-feet tall. In fact, you’d be hard pressed to find it among so many other giant trees.

Redwoods, one of the oldest living species on earth, have put down roots along what-is-now coastal California since the Jurassic (as many as 208 million years ago). While the “oldest known specimen,” according to Wikipedia, “is about 2,200 years old,” individual Redwoods routinely live for up to 1,800 years. When mankind first arrived on the North American continent, Redwoods occupied a vast swath of land (more than 2 million acres), but due to habitat loss and logging—we cut down more than 70% of the Redwoods for decks, patio furniture, railroad ties, and bar tops—coastal Redwoods currently occupy a mere fraction of its ancient territory. And now, climate change has begun to have an effect on what remains of that ancient forest.

On a positive note, scientists have found that Redwoods absorb more carbon dioxide from the environment than any other tree, making them something of a climate-change champion. And the warmer temperatures of the last decade or more have encouraged a considerable growth spurt among California’s Redwood population.

But no matter how much carbon they remove from the environment or how much they might grow due to the record high temperatures we’ve experienced during the last decade, Redwoods, like other vegetation, need water, and the giants of Northern California have suffered the reduction of two sources of irrigation: rainfall and fog.

Five years of drought have stressed coastal Redwoods and killed millions of trees of various species throughout the state. Everyone had hoped that this year’s El Niño event would bring needed relief to the parched stare. And, thankfully, the El Niño did deliver above-average January rainfall, which also helped build a deep and welcome snowpack. Californians saw virtually no rain in February, however. And we’re still waiting to see if March will prove as wet as meteorologists have been promising. But what about the future? Will El Niño come back again next year, bringing another above-average rainy season? Or will the drought return to California instead? At this point no one knows.

We do know, however, that Redwoods have not only suffered reduced irrigation due to drought; they’ve also experienced considerable reductions of coastal fog, a decrease that has persisted for more than a hundred years.

“Since 1901, the average number of hours of fog along the coast in summer has dropped from 56 percent to 42 percent, which is a loss of about three hours per day,” said study leader James A. Johnstone, who conducted the research while working on his Ph.D. at the University of California, Berkeley, and is now at the University of Washington in Seattle.

When fog forms along the coast, it envelops the trees, settling on branches high above the ground. Throughout morning hours, more and more moisture accumulates on Redwood limbs and branches—until, that is, gravity takes over. Then thousands of heavy water droplets plummet to the ground, sinking into the soil and delivering moisture to the massive root systems of the Redwoods. And they need that water. The thirsty trees require “500 gallons of water a day.” During the rainy season (in non-drought years), Redwoods get ample water from rainfall; but for seven to eight months of the year, fog delivers the only daily soaking the trees receive. The fog delivers water to the roots and provides a significant increase in humidity that helps the trees retain moisture during the hot and dry days of summer.

Over the more than 200 million years that they’ve thrived along the Pacific coast, Redwoods have experienced many periods of drought, some longer and more severe than the current five-year drought. But today’s climate is both drier and hotter. And long-range forecasts suggest that temperatures will only increase over time as we pump more and more carbon dioxide into the atmosphere. Redwoods in the northern sector of their range have already begun to expand northwards in response to the changing climatic conditions. But forests in the southern section of the range—in Big Sur, Monterey, the Santa Cruz mountains, and San Francisco—may not fare as well. Can you imagine a Muir Woods without Redwoods?

For more information about the decreased fog, see “Less Fog in California Could Stress Redwoods” and “Lack Of Fog Is A Threat To Northern California’s Majestic Redwoods.”

To read more about climate change and its effects on coastal Redwoods, see “Understanding Climate Change” on the Save the Redwoods site, “Redwood Trees May Help Battle Climate Change, Study Finds,” “Redwoods keep the climate healthy for us all,” Humboldt State’s “Multi-Year Project Looks at Redwoods and Climate Change,” Phys.org’s “Future coastal climate not cool for redwood forests,” “California Redwood Relocation: Earth’s Largest Trees Shift Northward With Climate Change,” “Climate Change in Coast Redwood Forests,” “Redwoods growing faster in a warmer climateGiant Redwoods Growth Spurt Tied to Climate Change: Study>.”

You’ll also find much more about this most majestic species in Wikipedia’s article on “Sequoia sempervirens” and on the Save the Redwoods.org site.