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TOPIC: Mesoamerican Megadrought

Blobrana

L

Posts: 131433

Date: Jun 1 23:47 2012

Medieval megadrought	Permalink

University of Nevada, Reno scientists confirm Sierra Nevada Medieval megadroughts 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. 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. Read more __________________

Blobrana

L

Posts: 131433

Date: Feb 3 18:08 2011

Mesoamerican Megadrought	Permalink

Trees Tell Tales of Mesoamerican Megadroughts A new, detailed record of rainfall fluctuations in ancient Mexico that spans more than 12 centuries promises to improve understanding of the role drought played in the rise and fall of pre-Hispanic civilizations. Prior evidence has indicated that droughts could have been key factors in the fates of major cultures in ancient Mexico and Central America (Mesoamerica). But there have been many gaps in the paleoclimate record, such as the exact timing and geographic extension of some seemingly influential dry spells. The new, 1,238-year-long tree-ring chronology, the longest and most accurate of its kind for Mesoamerica, is the first to reconstruct the climate of pre-colonial Mexico on an annual basis for more than a millennium, pinning down four ancient megadroughts to their exact years. Read more __________________

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