As a young reporter, Mark Twain visited Lake Tahoe. Its clear, cobalt blue water so entranced him that he wrote of it later, in “The Innocents Abroad.”
“I have fished for trout, in Tahoe,” Twain wrote, “and at a measured depth of eighty-four feet I have seen them put their noses to the bait and I could see their gills open and shut.”
Surface temperatures are rising faster than scientists have ever recorded. The “deep mixing” that oxygenates the lake bottom hasn’t happened in four years. And forget trout at 84 feet. Last year, the 10-inch white disk scientists lower into the lake to gauge that “wonderful transparence,” as Twain called it, averaged 73.1 feet before it disappeared into the murk.
In years past, such concerns have been addressed with curbs on development and runoff; now, however, scientists say the very physics of the water have been altered by climate change. Global warming has meant less snow at the lake and warmer water, more rain in the mountains and more runoff. Those changes, in turn, have worsened algae and fine sediments.
So it goes, one more alarm in an alarming season. This week, the National Oceanic and Atmospheric Administration released a 300-page report on the state of the climate in 2015: Global temperatures hit record highs, as did the surface temperatures of the oceans, as did sea levels, as did the atmospheric concentration of greenhouse gases. Glaciers are going, going, gone.
Separately, thawing permafrost has been cracking and buckling roads, buildings, runways and energy pipelines. A report this week from Bloomberg found that the 1,387-mile Alaska Highway, one of North America’s critical arteries, is so badly damaged that, in some fissures, a human being can jump in and walk.
In this context, Lake Tahoe is just one twitching casualty in a worldwide war zone. Still, just two hours by gas guzzler from the Capitol, it underscores the ongoing importance of California’s hard environmental work.
The Tahoe findings suggest a need to rethink lake preservation, and recalibrate targets for this century’s climate. Let’s hurry. It would be tragic if humans managed, in the short span since Twain roamed the Sierras, to destroy a wonder that nature took a million years to form.