El Nino-Southern Oscillation is a climate pattern that occurs across the tropical Pacific Ocean approximately every five years. The phenomenon includes a change in ocean temperature—the "El Nino" component—and a change in air surface pressure—the "Southern Oscillation" component. When prolonged, above-average ocean warming coincides with higher air surface pressure, the phenomenon is popularly called El Nino; when prolonged, above-average ocean cooling coincides with lower air surface pressure, the phenomenon is popularly called La Nina. El Nino or La Nina events typically last between five and nine months. El Nino begins with increased surface pressure over the Indian Ocean and reduced air pressure over the central and eastern Pacific Ocean, a combination which causes trade winds traveling from Peru to the Eastern Pacific to subside. Under normal conditions, these trade winds blow warm water near the surface away from Peru along the Equatorial Current, leading to an upwelling of cold, nutrient-rich water. During an El Nino, however, this effect is reduced. Because the Pacific Ocean has a potent impact on climate throughout the world, El Nino disturbs weather patterns more powerfully than does any other known force. Typical effects include severe droughts in Indonesia, Australia, and the Philippines, and substantially increased rainfall in parts of South America.

The effects of El Nino can be economically devastating in South America. Because of the increased rainfall, flooding in Peru and Ecuador is common. Moreover, El Nino significantly diminishes the amount of cold water that usually rises from the deep, depriving local fish populations of the important nutrients brought up with the cold water. In the absence of these nutrients, fish swim deeper, head south, or die off, causing great harm to the fishing industry. Indeed, during the 1972 El Nino, the world's largest fishery collapsed. In addition, these same fish feed local bird populations; during an El Nino event, birds, the droppings of which are used in the fertilizer industry, leave to find new food sources. Although no one knows how long El Nino has existed, evidence suggests that there may have been El Nino phenomena for thousands of years. Coral records suggest a warming of sea surface temperatures as early as 3,000 B.C.E. Five hundred years ago, fishermen in Peru saw their anchovy catch diminish substantially when water temperatures warmed. The most destructive El Nino event occurred in 1982-1983, when droughts and associated wildfires killed nearly 2,000 people; this incident sparked intense occupation among scientists worldwide with the causes of El Nino.

In the last sentence of the passage, the word occupation most nearly means

A. function
B. employment
C. concern
D. affair
E. professionalism




The passage suggests which of the following about phenomena associated with El Nino?

❑ The surface water of the Pacific Ocean near South America is warmer because of reduced trade winds.
❑ Severe droughts are seen in some parts of the world, while increased flooding is seen in other parts of the world.
❑ Because many fish relocate or die, fewer fish are caught by many people in the South American fishing industry.



On the basis of the passage, it can be inferred that

A. In the absence of an El Nifio event, drought conditions are rarely present in Indonesia, Australia, or the Philippines.
B. No observable phenomenon influences global weather patterns to a magnitude greater than does an El Nino event.
C. Because of the changes in surface pressure and reduction in trade winds associated with El Nino events, many South American birds are forced to relocate.
D. The El Nino event of 1982-1983 caused more deaths than did any other climate-related event that year.
E. The effects of the 1972 El Nino event were felt most profoundly in Peru and Ecuador.