ShareThisBy BILL LINDELOF
Sacramento Bee
Thursday, August 16, 2007
Climate change is warming frigid Lake Tahoe, air temperatures are rising, and the alpine lake's famous clarity is being degraded, according to a new report by the University of California, Davis.
The report by the UC Davis Tahoe Environmental Research Center is designed to give the public easy-to-understand information about changing water quality and weather conditions at Lake Tahoe.
For the most part, it is not good news.
"Nighttime minimum temperatures are rising, there is less snow and more rain, and there are fewer freezing days per year," said Geoff Schladow, an expert on lake health and director of the UC Davis Tahoe Environmental Research Center.
The report, "Tahoe: State of the Lake Report 2007," summarizes UC Davis scientific observations of weather and water conditions compiled since the 1960s. Some weather information dates to 1911.
Researchers say the data strikingly show that the Tahoe climate is warming up --which could have implications for those who like to vacation in the Lake Tahoe basin. For instance, there could be less snow for skiing.
Warming signs include nighttime low temperatures that have increased four degrees since 1911.
Cold days are fewer in the basin -- days with average air temperatures below freezing dropped from 79 to 52 days since 1911.
Along with rising air temperatures, lake waters are not as frigid. The average July surface water temperature has increased almost 5 degrees, from 62.9 degrees to 67.8 degrees Fahrenheit, since 1999.
Rising water temperature since 1978 is affecting Lake Tahoe's ecosystem, said Schladow. Types of algae are changing and starting to grow earlier in the year. In addition, invasive bass and carp -- warm-water fish -- are becoming more common. He said the changes are related to the warming global climate. Tahoe is an ideal place to monitor the effects of climate change because of the length of researchers' environmental record-keeping.
Lake Tahoe's air and water are warming because of the atmospheric buildup of greenhouse gases, Schladow said.
"There is a tremendous amount of research going on around the world on the impacts of climate change," he said. "What the Tahoe community needs to be aware of is that going forward they cannot ignore climate change."
Lake Tahoe's health has mostly been talked about in terms of clarity. UC Davis' new report gives a more comprehensive look at the lake, Schladow said, presenting information on meteorology and biology as well as the clarity of Earth's 11th-deepest lake.
In 2006, water transparency declined.
"During wet years of extraordinary runoff, we expect to see dips in clarity," said Julie Regan, Tahoe Regional Planning Agency communications and legislative affairs chief, in a press release. "The 2006 reading is what we would expect based on runoff conditions."
She said officials remain committed to improving clarity at Lake Tahoe: "We must sustain our investment in environmental improvements if we want to achieve this important goal for future generations."
The report can be viewed online at terc.ucdavis.edu.
(Bill Lindelof can be reached at blindelof(at)sacbee.com)
