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Most of the 70 people in the audience at the Tahoe Center for Environmental Research Wednesday night had seen Al Gore's "An Inconvenient Truth" or were at least familiar with the concept of global warming.
The idea of climate change could bring devastation to the polar ice caps, cause the ocean to rise as much as five meters over the next century - flooding coastal cities, and bringing extinction to the Arctic Fox and Polar Bear. What they might not have guessed is that these global changes, by the year 2090, could raise temperatures in the Tahoe basin five degrees, create an annual snowpack just 20 percent what it is now and turn the lake green - yes, green.
Guest lecturer, UC Davis research ecologist Robert Coats recently completed a study analyzing a 33-year data set of more than 7,300 measurements of lake-water temperature collected by UC Davis scientists.
He found from 1969 to 2002, the lake's water temperature increased, on average, 0.027 degrees Fahrenheit per year, which means the waters of Lake Tahoe are warming up almost twice as fast as the world's oceans.
The rapid warming rate jeopardizes the lake's blue waters.
"The climate trend is demixing the lake which will make an impact in the clarity of the lake," Coats said. "Tahoe is strongly influenced by big global-scale climate changes.
The idea of climate change could bring devastation to the polar ice caps, cause the ocean to rise as much as five meters over the next century - flooding coastal cities, and bringing extinction to the Arctic Fox and Polar Bear. What they might not have guessed is that these global changes, by the year 2090, could raise temperatures in the Tahoe basin five degrees, create an annual snowpack just 20 percent what it is now and turn the lake green - yes, green.
Guest lecturer, UC Davis research ecologist Robert Coats recently completed a study analyzing a 33-year data set of more than 7,300 measurements of lake-water temperature collected by UC Davis scientists.
He found from 1969 to 2002, the lake's water temperature increased, on average, 0.027 degrees Fahrenheit per year, which means the waters of Lake Tahoe are warming up almost twice as fast as the world's oceans.
The rapid warming rate jeopardizes the lake's blue waters.
"The climate trend is demixing the lake which will make an impact in the clarity of the lake," Coats said. "Tahoe is strongly influenced by big global-scale climate changes.
Warmer temperatures and less mixing of the lake's waters has two effects Coats said: less dilution of particle concentrations in the surface water each winter, and fewer nutrients coming from the deep waters to stimulate algal growth, keeping the water more murky.
Coats, toward the end of his presentation, showed a picture of Big Bear Lake, which is at a similar elevation to Tahoe 100 miles northwest of Los Angeles.
Big Bear Lake is an emerald green color.
"I don't want to send waves of panic, but this is what we could be looking at," he said. "We hope not, but it's the reality we have to face."
Another possible contributor to the lake's degradation could be the stream runoff, should the predicted precipitation in the basin change.
Incline resident Ron Stichter asked Coats, "What would you predict stream effluent into the lake with greater rainfall than snowfall."
"The concentrations (of sediment) are much hire during rainfall," Coats said.
Coats, toward the end of his presentation, showed a picture of Big Bear Lake, which is at a similar elevation to Tahoe 100 miles northwest of Los Angeles.
Big Bear Lake is an emerald green color.
"I don't want to send waves of panic, but this is what we could be looking at," he said. "We hope not, but it's the reality we have to face."
Another possible contributor to the lake's degradation could be the stream runoff, should the predicted precipitation in the basin change.
Incline resident Ron Stichter asked Coats, "What would you predict stream effluent into the lake with greater rainfall than snowfall."
"The concentrations (of sediment) are much hire during rainfall," Coats said.
But the change does not stop with the lake water.
An assessment that the basin could turn to a more coniferous forest (the five-degree rise in temperature would cause the climate here to be similar to that of 3,700 feet) was met with one key question:
"Does that mean we could grow food here?" asked Incline resident Jacque Chandler, to some appreciative chuckles from the rest of the audience.
"Not really, just because we're warming up, doesn't mean the soils will change," Coats said. "The forest we see here today may well be a climactic relic. Forest planners should start thinking about what can grow here in 100 years.
If these discoveries caused concern in the audience Wednesday, the ramifications of the warming of the basin could be far-reaching, Coats warned, deferring to Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center.
"Weather-pattern changes in the northern Sierra are likely to affect water supplies for cities and agriculture in much of California," he said. "They have the potential to impact the entire operation of the state's system of reservoirs and rivers, and the ecological systems they support."
An assessment that the basin could turn to a more coniferous forest (the five-degree rise in temperature would cause the climate here to be similar to that of 3,700 feet) was met with one key question:
"Does that mean we could grow food here?" asked Incline resident Jacque Chandler, to some appreciative chuckles from the rest of the audience.
"Not really, just because we're warming up, doesn't mean the soils will change," Coats said. "The forest we see here today may well be a climactic relic. Forest planners should start thinking about what can grow here in 100 years.
If these discoveries caused concern in the audience Wednesday, the ramifications of the warming of the basin could be far-reaching, Coats warned, deferring to Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center.
"Weather-pattern changes in the northern Sierra are likely to affect water supplies for cities and agriculture in much of California," he said. "They have the potential to impact the entire operation of the state's system of reservoirs and rivers, and the ecological systems they support."
A handful of audience skeptics questioned whether this data will be supported over time, and whether global warming is real to which Coats' message was simple:
"We have the data we have, as far as we know there has never been a warming trend like this - it's off the charts," Coats said. "There's a lot of cycles in the earth's history of warming and cooling, but they were extremely long cycles, this is extremely rapid and unprecedented.
Coats, a consulting hydrologist, also owns the firm Hydroikos Ltd. in San Rafael.
What can you do:
Ecologist Robert Coats encouraged basin residents to log on to www.climateprediction.net, an experiment to porduce a forecast of the climate in this century. All it takes is a computer.
"It's a great experiment and something you cand do to help out with not a whole lot of effort," Coats said.
"We have the data we have, as far as we know there has never been a warming trend like this - it's off the charts," Coats said. "There's a lot of cycles in the earth's history of warming and cooling, but they were extremely long cycles, this is extremely rapid and unprecedented.
Coats, a consulting hydrologist, also owns the firm Hydroikos Ltd. in San Rafael.
What can you do:
Ecologist Robert Coats encouraged basin residents to log on to www.climateprediction.net, an experiment to porduce a forecast of the climate in this century. All it takes is a computer.
"It's a great experiment and something you cand do to help out with not a whole lot of effort," Coats said.
