Tahoe scientist: ‘We’re living in a climate change affected world now’

INCLINE VILLAGE, Nev. — Back in August the Sierra Sun reported that researchers found that Lake Tahoe’s temperature is rising at its fastest rate yet.

Last week, we learned it isn’t the only one.

Researchers have found that temperatures are rising at a higher rate in mountain environments than they are in other regions.

“If you’ve been backpacking anytime in the last few years, you feel it,” said Dr. Steve Sadro, a limnologist at the University of California, Davis department of environmental science and policy, told a crowd last Thursday night.

“We’re living in a climate change affected world now,” he continued. “I think that’s really an important point to make. You can feel these things — you can look out the window and see these effects. Things are different now than they were 30 years ago.”

Sadro’s talk, titled, “Climate change and lake temperature in the Sierra Nevada: There’s no business like snow business,” was given as part of the university’s monthly evening lecture series at its Tahoe Environmental Research Center on the Sierra Nevada College campus in Incline Village.

The focus of his research is on aquatic ecosystems. He studies backcountry lakes in the Sierra Nevada, and tries to understand how different factors are impacting them.

He said that one of the challenging things about trying to understand those ecosystems is getting to them. Since they’re not accessible by car, these lakes require skiing or hiking in and sometimes carrying heavy equipment.

Gear often has to be carried by undergraduate student assistants or by mule, he said.

And there’s another challenge: money.

“The funny thing about these projects is funding is very irregular for them, and so we’re left often times to cobble together funding from multiple sources,” he said. “Sometimes there are gap years where we struggle to keep the record alive.”

There are thousands of lakes in the Sierra, so understanding the various factors that impact them is complicated.

Groundwater, for example, isn’t a factor for all lakes but can change the temperature of some. Things like solar exposure and air temperature also have an impact on the lakes, just as snowpack does — but the effects of snowpack vary seasonally.

“In years where there’s a lot of snowpack, the spring lake temperatures are generally cold,” Sadro said. “Its only those years where there’s hardly any snow at all that you see the lake temperatures warming, and so there’s a relationship there — it’s just not linear.”

He added that by fall, the lake temperatures respond “more or less independently of the legacy of snowpack,” which means there are other factors playing a stronger role in affecting the lake temperature.

Sadro said the goal of his work is to be able to help determine which lakes are most vulnerable to the effects of drought — a situation that despite recent snowfall is becoming increasingly common, as the Earth’s overall temperature continues to rise.

“The Sierra are warming, and we’re seeing rates of warming that are very fast and consistent with rates of warming that are seen in other mountainous regions of the world.” Sadro said. “We’re seeing drought frequency increase over the long term, the severity of drought increasing as a result of diminishing input, and also as a result of increasing air temperature; we’re seeing the role of snow in regulating lake temperatures being very, very important for many small lakes, and then finally we’re thinking about ways in trying to assess the risk at bioregional scales of these things on lake temperature.”

There are thousands of lakes in the Sierra, many of which are in the Lake Tahoe area. Sadro said he and his team are hopeful they can predict which of those many lakes are most vulnerable due to loss of snow.

Amanda Rhoades is a news, environment and business reporter for the Sierra Sun. She can be reached at arhoades@sierrasun.com, 530-550-2653 or @akrhoades.