Climate change could claim Giant Sequoias

There is no more poignant or sorrowful manifestation of climate change than a Giant Sequoia burning down. The most ancient of these majestic trees are well over 2,000 years old. Just think: This means that trees alive today were already living at the time of Jesus. It also means that today’s seedlings, if they are allowed to grow to maturity, will still be alive in the year 4,000. That’s a big if.

The tallest of the giants tower more than 200 feet above the ground. The widest are over 20 feet in diameter. They include the biggest tree in the world by volume, the General Sherman.

Giant Sequoias grow in nature exclusively on the western slope of

California’s Sierra Nevada range, where a combination of environmental factors and the trees’ adaptation to such factors create an ideal habitat – or did until recently. The habitat in which the Giant Sequoias have thrived for centuries includes intermittent low-intensity wildfires that clear out dead and down wood and brush and expose the sequoia cones to heat that causes them to open up and release their seeds.

The natural history of the Sequoia groves also includes an absence of the kind of extreme and prolonged drought found there today. The trees’ survival through the centuries has also been fostered by their soft, reddish, thick bark, which is fire resistant, protecting the underlying wood from the ravages of flame, as long as the flames don’t reach too high or become too intense. Their unique and effective survival mechanisms and hence the longevity of the trees have led to their nickname, “the immortals.” But events in the past two years have given us new reason to question the viability of that label.

Last year, the high intensity Castle Fire swept through Sequoia groves and destroyed an unprecedented estimated 10 percent of the world’s population of Giant Sequoias.

This year, the KNP Complex and Windy Fires, both high-intensity fires burning in and near Sequoia National Park, have destroyed at least dozens, and more likely hundreds or thousands, of the trees. Factors that make fires such as the Castle, KNP and Windy Fires’ highintensity blazes capable of burning through the trees’ fire-resistant bark and capable of reaching the trees’ exposed canopies some 200 feet above ground, include large quantities of extra dry vegetation near the base of the trunks and warmer and drier air. These factors are linked, in turn, to climate change, especially global warming. Some scientists involved in the study of the relationships between Giant Sequoias and today’s fires have suggested just recently that extinction of the species is a possibility.

We were already well-aware of the urgency of reversing global warming. Now we have fresh evidence of what horrific destruction of nature will result if we fail.