Thursday, June 7, 2012

Sierra Nevada 200 year megadroughts confirmed

Terra Daily via SPX: The erratic year-to-year swings in precipitation totals in the Reno-Tahoe area conjures up the word "drought" every couple of years, and this year is no exception. The Nevada State Climate Office at the University of Nevada, Reno, in conjunction with the Nevada Drought Response Committee, just announced a Stage 1 drought (moderate) for six counties and a Stage 2 drought (severe) for 11 counties.

Reno, Lake Tahoe and the Sierra Nevada are no strangers to drought, the most famous being the Medieval megadrought lasting from 800 to 1250 A.D. when annual precipitation was less than 60 percent of normal. The Reno-Tahoe region is now about 65 percent of annual normal precipitation for the year, which doesn't seem like much, but imagine if this were the "norm" each and every year for the next 200 years.

Research by scientists at the University of Nevada, Reno and their partners at Scripps Institution of Oceanography in San Diego indicates that there are other instances of such long-lasting, severe droughts in the western United States throughout history.

Their recent paper, a culmination of a comprehensive high-tech assessment of Fallen Leaf Lake - a small moraine-bound lake at the south end of the Lake Tahoe Basin - reports that stands of pre-Medieval trees in the lake suggest the region experienced severe drought at least every 650 to 1,150 years during the mid- and late-Holocene period....

Thomas Hill's 1864 painting, Emerald Bay, Lake Tahoe

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