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Opinion: Global warming and the Sierra Nevada mountains

Robert W. Derlet, M.D.
Tribune Guest Column

My first memory of the mighty Sierra Nevada Mountains was at age 6, during a summer week in Yosemite along with a youth group. Sleeping under the stars on a soft bed of pine needles by night and exploring the peaceful trails, forests, and waterfalls by day forever touched my heart. My parents must have sensed my excitement with nature; thereafter we began annual family visits to Yosemite. At that young age, I never dreamed I would be writing this column or running in 2016 for the U.S. Congress in a district that includes the impressive beauty of Lake Tahoe.

My 10th grade high school aptitude test said I should choose a career as a forest ranger. Instead, I became a doctor. I never lost my love of nature; even choosing to attend UC Santa Cruz, a campus nestled in a redwood forest. Trips to the Sierra continued, but it was not until I was in medical school at UC San Francisco that my eyes first gazed with amazement upon Lake Tahoe. How could water be so clear? That question motivated me to develop a research interest in all waters in the Sierra Nevada.

First, let me tell you why a physician would hike thousands of miles through the wilderness and backcountry of California, photographing lakes and streams and collecting samples of water. My science pathway began at the University of California, Davis. I worked at the UC Davis Medical Center for over 20 years, with assignments ranging from Chief of the ER to Chief of Staff. I was on a faculty track that gave me 20-percent time for research. I used that time to study water in the High Sierra, searching for microbes that could harm us humans if we drank the water untreated. I worked with UCD Tahoe Researcher Professor Charles Goldman, and learned of the interconnectivity of ecosystems. For example, algae you see in Sierra lakes and streams are covered with a film of bacteria.



Over time, as I hiked trails that link Lake Tahoe to Yosemite and Kings Canyon, I learned that many agencies oversee the vast watershed, most notably the federal government. Today, with the help of 2011 redistricting, one congressional district covers California’s most important watershed. The 4th District covers our mountains and foothills, stretching 200 miles from Lake Tahoe to Kings Canyon.

Sadly, the tranquility of the Sierra and Lake Tahoe is under threat from more than just drought, fire, Central Valley air pollution, and in some areas, overdevelopment. The greatest threats are the multiple impacts of global warming. Temperatures of high country lakes and streams have increased, as have nighttime air temperatures. Lake Tahoe’s huge volume has warmed four degrees at the surface and a whole degree down its 500-meter water column in just 30 years.



In the wilderness watersheds, I have noted progressive increases in algae biomass and risk of algae blooms and associated toxins. California’s four-year drought may continue. Our everyday lives and the economics of an area whose wealth is strongly linked to the visitation to majestic Lake Tahoe, and recreational use of nearby streams and lakes, are impacted by a warming climate. There is no doubt that human activity has changed our planet. The year 2015 turned out to be the warmest year in recorded history. It is chilling to think that this rate of earth warming is exponential.

We are lucky that much of the water in the Sierra Nevada — taken from side streams and remote lakes — is still safe to drink untreated. It might contain as much as 5,000 bacteria per quart, but these are good bacteria; think of them as probiotics. The harmful microbes, like giardia, salmonella and toxic E. coli, are usually found only in heavily used areas or areas grazed by cattle. Swim a mile from the shoreline of Lake Tahoe and you can drink the water, untreated. We must fight keep it this way.

I support the Paris Agreement on global warming, but that is only a first step. We must more rapidly convert to renewable energy such as wind and solar, and decrease use of fossil fuels. In congress, I will take the lead in fighting for measures that halt global warming and also protect the Sierra watersheds and clear waters of Lake Tahoe. I enlist the support of the people who live in the Lake Tahoe area to keep Tahoe blue.

Dr. Robert Derlet is a 2016 Democratic candidate in Congressional District 4.


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