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El Niño/Southern Oscillation (ENSO) Effects
The El Niño of 1997–98 is estimated to have cost some $20 billion (U.S. dollars) in worldwide damage. The El Niño of 1982–83 tallied up some $13 billion in damages. La Niña events are less well studied, but they also inflict damages by drought, floods, wildfires, Atlantic hurricanes (average damage per storm is about $1.6 billion), etc.
Example geographic areas show the effects of extreme events in the ENSO cycle and their impacts upon humanity.
Example weather phenomena show the effects of extreme events in the ENSO cycle and their impacts upon humanity.
Example diseases show the effects of extreme events in the ENSO cycle and their impacts upon humanity.
Cholera—Global ENSO cyclic changes in climate influences the spread of cholera by forcing the spread and use of contaminated water.
Hantavirus Pulmonary Syndrome—In the Americas, ENSO cyclic changes in climate influence the spread of Hantavirus Pulmonary Syndrome (HPS) by spreading rodent vectors into contact with people.
Malaria—Around the globe, ENSO cyclic changes in climate influence the spread of malaria by spreading malaria-transmitting mosquitoes into contact with people.
Rift Valley Fever—In Africa, ENSO cyclic changes in rainfall alter the distribution of wetlands. Mosquitoes spread in contact with domestic animals and people, causing outbreaks of Rift Valley fever.
Example wildfires show the effects of extreme events in the ENSO cycle and their impacts upon humanity.
Jump to 'Introduction' List of Web Sites
For ENSO science and history, jump to the ENSO Cycle page.
Introduction
El Niño and La Niña events are respectively hot- and cold-water extremes in the equatorial Pacific Ocean. Over many years, the surface waters cycle from one extreme to another. The cycle has been named the El Niño / Southern Oscillation (ENSO) cycle.
Each deviation from the long-term average has local effects in the central and eastern Pacific Ocean, and effects in distant geographic areas through atmospheric and oceanic teleconnections. Out of many possible examples, this CD-ROM presents sample effects and impacts dealing with tropospheric temperature and humidity, which link the surface of the ocean with the jet stream and with rainfall patterns. In a consideration of the Antarctic currents and sea ice, the equatorial Pacific waters are linked with the circumpolar waters of the World Ocean to affect Antarctica and Australia. 2 different considerations of both ocean and atmospheric currents present some of the effects of changes in weather patterns on the northeastern Pacific Ocean and west coast of North America and Caribbean corals and North African dust.
ENSO, the Pacific decadal oscillation, and other planetary circulation patterns have steered the weather- and moisture-delivering jet stream to the north of its average path for the past few winters, resulting in warm winters all across the United States (MODIS snow data) and very dry conditions on the east and west coasts. In El Niņo years, the jet stream is steered farther south, resulting in record snowfalls and very wet conditions on the east and west coasts. The resulting drought and floods, hurricanes and severe storms, excess or lack of snowfall, and conditions favorable for the spread of wildfires and various diseases impact human activities in various portions of the globe.
Many studies have been started to determine the record of historic El Niños and to predict and study the next one. These studies have included "lessons learned" in each of several countries, from predicting the 1997–98 El Niño. With successful predictions of extreme events and their intensities, the impacts can be mitigated. With the global view and repetitive coverage provided by satellites, remotely sensed data are vital to the monitoring and understanding of ENSO events and impacts.
Disclaimer: NASA offers these suggested sites for additional information regarding effects and impacts of ENSO events that deviate from the long-term average (El Niño/La Niña events). Web access is required to reach these sites. Link existence and contents are not under the control of the EOSDIS Science Operations Office.