Water quality implications of temperature change not yet understood
By Summit Voice
SUMMIT COUNTY — California’s Lake Tahoe is warming up twice as fast as the world’s oceans and at about the same rate as other major lakes in the world, including the Great Lakes Lake Zurich, Switzerland; and Lake Tanganyika, Africa, according to a new study from UC Davis that tries to pinpoint global warming impacts in the Sierra Nevada.
Over the 33-year study period, the temperature increased about 0.88 degrees Fahrenheit. The research team also looked at air temperature records in the Tahoe area, finding that nighttime air temperatures have increased an astounding 3.6 degrees fahrenheit in the past 90 years, which helps explain the warming water temperatures in the lake.
Next, the scientists want to try and understand how the warmup will affect efforts to keep the lake water pure. Warmer waters will probably mean less mixing in Tahoe, which could reduce the amount of dilution — or it could result in fewer nutrients being transported from deep in the lake to near the surface, which could reduce the growth of algae and make the water more clear.
Cleanup efforts at Tahoe have focused on the impacts of growth and development in the basin, but the new research suggests that climate change impacts will also figure into the equation.
The basis of the study was an in-depth analysis of more than 7,300 temperature measurements collected by UC Davis scientists. The number-crunching showed an average annual temperature increase of about 0.027 degrees per year.