What the Ancient Redwoods Tell Us about Climate Change

Around the time of the Golden Age of Greece, when Socrates was laying the groundwork for all western philosophy, some of the oldest trees living today began their lives as part of a massive grove that dates back to the ice age.  The forest once spanned from California to Minnesota, but is now confined to a narrow sliver along the California coast.  We did most of the damage -- felling trees for timber and highways -- but its latest threat is climate change.

Humboldt State University professor, Steve Sillet, is monitoring the threat in excruciating detail, using hair-raising methods.  His team has selected trees from 16 plots around the state and are measuring the height, width, and lean of the trees and mapping each branch to create detailed 3D images of the trees--from base to tip, trunk to leaf.  It’s an ambitious task that can require four days per tree to map.  They hang from these giants like window-cleaners, dangling hundreds of feet off the ground, with measuring tape in hand.  This project, Sillet argues, will show how the trees, especially the tallest ones, have responded--and will respond--to climate change. “Because they’re so long lived, we can get a sense of how unusual are these changes now compared to what the trees have experienced over that past thousand to two thousand years.”


This is not a rescue mission. “The battle for these redwoods has been fought and mostly lost,” says Sillet.  When Americans came west during the Gold Rush, two million acres of ancient redwood forest sprawled across the map (Save the Redwoods League).  Ninety-five percent of that forest were cut down by loggers who found a high quality wood that could be used to build a mansion out of a single tree.  It was also used for pipes, gutters, shingles, boats--it is hard, water proof, and immune to termites.  (From A Natural History of North American Trees.)  Despite being hard-wired for longevity, the remaining forest, which has survived drastic changes in climate in the millions of years it has existed, may not survive the rapid climate change we see now.

The tallest trees are particularly vulnerable, according to Sillet (Read more about his research in Humbolt State’s magazine).  They require vast amounts of water to grow and depend on the warm, moist ecosystem of the area the trees are adapted to.  The research has already shown that the trees are actually growing more than they have in the past, probably caused by the increase in carbon dioxide.  The future is uncertain for these giants, but we may be witness to the final days of one of the cultural touchstones of the American West and a wonder of the natural world.

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