Lake Tahoe is overheated, underfilled and both its future and renowned crystal blue waters are murkier than normal.
The crown jewel of the Sierras and largest alpine lake in North America had a rough year in 2015, according to the new “State of the Lake” report from the UC Davis Tahoe Environmental Research Center, which finds the lake’s temperature is rising at its fastest rate ever.
It’s been said that Lake Tahoe is a complex body that man may never understand. That is true; however, UC Davis and Geoff Schladow, the director of the UC Davis Tahoe Environmental Research Center housed at Sierra Nevada College, are doing their best to prove that statement wrong—well, maybe, just a little bit wrong.
It seems that when experts think they’ve finally arrived at data that absolutely cannot be questioned, that same data is put into conflict with the patterns of human action and natural forces.
A little more than a year ago, California’s Gov. Jerry Brown ordered mandatory water reductions of 25 percent throughout the state. And in some areas, citizens were ordered to reduce consumption by 35 percent. This was all in response to more than four years of severe drought.
However, in June 2016, those mandatory reductions were lifted, mainly because the state was blessed with considerable rainfall the previous winter. As a result, local water agencies were given the authority to determine on their own whether mandatory water reductions were still necessary and, if so, what the amounts should be.
Several weeks ago, my daughters “graduated” from the third grade. The final day of the school year was an unusually warm June day, and after pizza and games, their teacher said goodbye for the summer after extracting a solemn promise – to read “at least 10 books” during their time away.
Ten chapter books in 10 weeks, I reminded them on our drive home – a healthy dose, remembering the pile at my bedside. Easy, they promised, no problem.
In the southern reaches of Egypt, the city of Aswan is one of the hottest and sunniest in the world. Temperatures reach 41C in the summer and less than a millimetre of rain falls each year. Some years it doesn’t rain at all.
Aswan may be one of the world’s least rainy places, but it’s not even close to being the most water-stressed city. It nestles on the east bank of the Nile, close to the Aswan High Dam and the vast Lake Nasser, one of the largest manmade lakes in the world. With a capacity of 132 cubic km, the dam serves the irrigations needs not just of Aswan, but Egypt and neighbouring Sudan as well.
It’s being called a marine heat wave. The combination of the strongest El Niño in recent history and the warm water anomaly known as the Blob generated the greatest amount of warm ocean water that has ever been recorded, possibly affecting marine life up and down the West Coast. New research has now linked the two phenomena, with each believed to be alternately affecting the other through the atmosphere and the ocean. El Niño is the warming of the equatorial Pacific Ocean and it can affect wind, temperature and precipitation patterns around the globe.
The drought that has caused profound impacts on California’s residents and businesses has similarly taken a toll on the San Francisco Bay-Delta ecosystem. In a world increasingly sensitive to the warning signs of ecological crisis — including climate change — the effect of the drought on species in the Bay-Delta requires careful attention.
Biologists warn Delta smelt, once the Delta’s most abundant fish, is on the brink of extinction.
Like many people who work on forestry issues in California, Jim Branham, executive officer of the Sierra Nevada Conservancy, is still trying to wrap his head around the drought’s toll on the region’s forests and the 66 million dead trees reported in the Sierra Nevada last month.
“It’s hard to comprehend,” he said, especially considering that in some areas of the Southern Sierra communities may see 85 percent of the trees around them dead or dying. “The magnitude of the problem is staggering,” he said.
Tribes are apprehensive, cities are more upbeat and farmers stand somewhere in between over a proposed plan to cut CAP water deliveries to keep Lake Mead from falling to dangerously low levels.
At separate meetings here this week, tribal officials, attorneys and irrigation officials grilled Central Arizona Project officials about the proposal. It would require a 33 percent cut in water deliveries once the lake dropped another 4 or 5 feet below where it’s expected to be at the end of this year, and cuts of up to 40 percent later.
Lake Tahoe is showing some severe impacts from the changing climate. Indicators released Thursday in the annual “State of the Lake” report packed a few surprises, even for scientists.
For one thing, the lake has been warming faster than ever recorded. In 2015 the lake’s average temperature rose 0.48 degrees Fahrenheit — and over the last four years, the rise was 15 times faster than the lake’s historic warming rate. “That came as a surprise to me,” says Geoffrey Schladow, a UC Davis freshwater scientist and lead author of the report.
