Losing Lake Tahoe to climate change

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.”

That was then. One hundred fifty years or so later, a new “state-of-the-lake” report issued last week by researchers at UC Davis has found that climate change has left the lake increasingly opaque and warm.

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 seeing trout 84 feet below the surface. 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.

This has been a summer of urgent alarms on global warming. Epic wildfires have consumed great swaths of California. Sea levels have risen and cities have been threatened by ever more violent storms.

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. The Northern Hemisphere saw 31 major tropical cyclones, another record. Extreme temperatures are more extreme than ever; glaciers and sea ice 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, the degredation of a world-class attraction that is visited by many Valley residents underscores the ongoing need for California’s hard environmental work.

What a tragedy it would be to lose one of the most breathtaking spots in the Sierra, scoured out of the earth by glaciers during the Ice Age. It took a million years to create Lake Tahoe, and less than a century and a half for humans to debase it. Climate change giveth. And to an extent that would surpass even Twain’s boundless imagination, climate change taketh away.

This story was originally published August 4, 2016 at 2:35 PM with the headline "Losing Lake Tahoe to climate change."