Lake Tahoe Have Been Warming at 15 Times its Historic Average in the Past 4 years, Study Reveals
The Tahoe Environmental Research Center (TERC) at the University of California Davis has released a new annual report revealing that the biggest alpine lake in North America is warming at a faster rate, with the warmest average surface temperature ever recorded occurring in 2015.
According to the "Tahoe: State of the Lake Report 2016," the average surface temperature of Lake Tahoe has been rapidly warming at over 0.3 degree Fahrenheit per year in the past four years, 15 times faster than its historic temperature. The lake also recorded the warmest surface temperature last year with 53.3 degrees Fahrenheit.
The report also noted that there are only 24 days of below-freezing average air temperature in the region, the lowest to be recorded. The precipitation in the region is near average, with only 6.5 percent fell as snow, the lowest amount ever recorded.
"The occurrence of rising air temperatures Lake Tahoe has been known about for many years now, and with it the warming of the lake. What is different this year is that we are seeing more aspects of the lake's internal physics changing, and that is bound to alter the ecology," said Dr. Geoffrey Schladow, TERC Director, in a statement.
Due to the fewer winter days and snow fall, Lake Tahoe failed to mix oxygen and nitrogen to its full depth for the fourth year in a row. Deep mixing is necessary to add oxygen to the depths and redistribute the nitrogen that accumulates at the bottom.
As a result of the failed deep mixing, the clarity of the lake fell to 73.1 feet last year, about five-foot decrease over the previous year. Furthermore, increase nitrogen in the water due to pesticides brought by runoff water during rainfall may encourage the growth of algae in the lake, which can also lessen the clarity of the lake.
However, the low levels of the lakes, which fell by nine inches in 2015, maintained the algae population in the lake at record-low levels. Lake Tahoe was below the natural rim for 364 days in 2015.