August 2000 Vegetation Index
	Data: Vegetation Anomaly · Vegetation Index · Average Vegetation Region: Africa · North America · South America
	Drought is by far the most damaging of all natural disasters. Worldwide, since 1967, drought is responsible for millions of deaths and has cost hundreds of billions of dollars in damage. The U.S. drought in 1988 alone cost an estimated $40 billion. Africa suffered its worst dry-spell of the century in 1991-92 when drought covered a region of 2.6 million square miles (6.7 million square km) and affected about 24 million people. What is drought and what causes it? How do we track it? Are we seeing more dry spells today, and are they growing longer and more severe? How early can scientists forecast the onset of a drought and what can be done to lessen its economic impact? Through the use of satellite remote sensors, researchers at NASA and NOAA have been monitoring the causes and effects of drought worldwide for the past two decades. This site presents an overview of the art and science of global drought monitoring, with maps showing regions affected by drought, updated monthly.				Drought: the Creeping Disaster Drought is defined in three ways: an extended period of below normal rainfall, a long term depletion of groundwater, or the stunting of vegetation growth due to a lack of water. Measuring Vegetation (NDVI & EVI) Scientists combine infrared and visible lightt information gathered by satellites to derive the normalized difference vegetation index, or NDVI, which indicates plant vigor. Dry Times in North America North American droughts follow the rhythms of several long term climate cycles, including El Niño. Related links and bibliography

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