Global warming affects lake |

Global warming affects lake

Gregory Crofton

As temperatures in the Northern Sierra Nevada increased over the last 30 years, so did the temperature of Lake Tahoe, according to a study led by Robert Coats, a scientist affiliated with the UC Davis Tahoe Research Group.

This warming trend in the lake – on average .027 of a degree a year, about .8 of a degree overall – has already affected the lake’s habit of mixing its dirtier near-surface waters with its deeper, cleaner waters, which could lead to a loss of its famed clarity.

Exactly how global warming will affect Lake Tahoe and its clarity is an issue yet to be tackled. Scientists who gathered Thursday in South Lake Tahoe to discuss the finer points of lake clarity indicated it is something they intend to include in their clarity models within the next couple of years.

“A warming lake is a more stable lake,” said Coats, who added that if the lake mixes less it is more apt to leave fine sediment, which contributes to clarity loss, near the surface for longer periods of time.

Ultimately, if global warming continues, a warmer lake could accelerate a condition that would release phosphorous trapped in sediment at the bottom of the lake, Coats said. That phosphorous would fuel a large amount of algae growth.

Coats recently submitted his study, “The Warming of Lake Tahoe,” to the scientific journal “Climatic Change” for review. Scientists Joaquim Perez-Losada, Robert Richards, Geoff Schladow and Charles Goldman, who founded the Tahoe Research Group, assisted with the study.

“Any warming is going to stimulate algal growth,” said Goldman, commenting on the study. “And it may actually have a small impact on fine particles contributing to clarity loss.”

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