Rains in the plains less common in past.After weathering a severe drought in 1988 and record floods in the 1990s, residents of the Great Plains believe they are keenly aware of climatic inconstancy in·con·stan·cy
n. pl. in·con·stan·cies
1. The state or quality of being eccentrically variable or fickle.
2. An instance of being eccentrically variable or fickle.
Noun 1. . Yet these recent meteorological turns provide only a small taste of what nature can dole out.
Before the year 1200, the northern Great Plains region faced far more frequent and severe droughts than it has in recent history, report scientists who have traced the area's climate patterns for the last 2,300 years. "This shows that the last 100 years are not representative of the kind of climate variability that we potentially can have in this region," says Kathleen R. Laird of Queen's University in Kingston, Ontario.
Laird and her colleagues reconstructed the climatic history of the region by studying fossil diatoms--shells from single-celled algae--preserved in sediments from the bottom of a lake in eastern North Dakota. They identified droughts by looking for Looking for
In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with. particular diatom diatom (dī`ətŏm', -tōm'), unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although some join to form colonies. species that thrive when the water level drops and the lake's dissolved salts and nutrients become concentrated. The scientists describe their work in the Dec. 12 NATURE.
During the last 750 years, droughts have occurred relatively infrequently, a finding that supports previous tree-ring analysis reaching back 500 years in near-by by Alberta. Before 1200, however, the diatoms diatoms
a series of unicellular algae, microscopic in size, with cell walls containing silica. Members of the family Diatomaceae. Their remains accumulate as geological deposits and are mined. See diatomaceous earth. record a much greater frequency of extreme droughts, many of which exceeded in intensity the Dust Bowl period of the 1930s. The longest dry spells lasted for centuries, from the years 200 to 370, 700 to 850, and 1000 to 1200.
Some of these droughts apparently affected large sections of North America, judging from studies of prehistoric climate in California. Rivers, lakes, and marshes in and adjacent to the Sierra Nevada dried up during the same three intervals recorded in North Dakota, according to Scott Stine of California State University Enrollment
Before drawing further conclusions about the drought history of North America This is the history of North America, an area where human habitation only started relatively recently, compared to Africa and Asia.
Scientists have several theories as to the origins of the early human population of the North America. , climate scientists need to study other lakes in the Great Plains and elsewhere, says Laird. Her study is the only high-resolution climate record of the midcontinent that reaches back more than 500 years.
Because droughts were more common before 1200, when temperatures were warmer, future glow warming may increase the frequency of droughts in the Great Plains, says Laird. This scenario draws some support from computer models that forecast how climate will react to greenhouse gas pollution. According to the models, greenhouse warming is likely to make climate more variable and to promote drying in middle North America, says James E. Hansen of NASA's Goddard Institute for Space Studies The NASA Goddard Institute for Space Studies (GISS), at Columbia University in New York City, is a component laboratory of NASA's Goddard Space Flight Center Earth-Sun Exploration Division and a unit of The Earth Institute at Columbia University. in New York New York, state, United States
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of .