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Typically, Pacific trade winds blow from east to west, transporting warm surface waters westward, east of Indonesia and northeast of Australia. Thus, the water maintains a cold temperature for much of the year. This is achieved by an upwelling of cold deep ocean-water, which benefits fisheries in the Pacific Ocean lying near the equator. However, these trade winds sometimes lose or gain strength in the Northern Hemisphere. This leads to an effect known as the Southern Oscillation which refers to the two recurring weather patterns of El Niño and La Niña. El Niño, meaning the "boy," is the phenomenon that results in the temperature of the sea surface off the coast of Peru increasing. This condition typically lasts for at least six months. Thus, there is a reduction in dissolved oxygen in the ocean so marine life declines devastating fisheries. It also fuels major differences in air pressure near the Pacific Ocean, which in turn leads to more severe weather events including droughts, increased precipitation, flooding, and even cyclonic storms like hurricanes. Usually, the eastern Pacific region has an upswing in heavy rains to cause flooding, and in contrast, Australia and Indonesia have droughts, often with accompanying forest fires. These two opposing weather events hurt agriculture. For instance, the 1982 – 1983 El Niño, recognized as the worst weather event of the century, hit hard in the U.S. by dropping huge amounts of rainfall on the southern California coast, which resulted in millions of dollars of damage while necessitating the evacuation of 10,000 people. El Niños counterpart, La Niña, meaning "the girl," contrastingly forms when Pacific trade winds grow more powerful than usual. It is the result of the cooler-than-average temperatures of South American equatorial surface waters which cause global cooling. La Niña's duration usually lasts for 9 to 12 months and although forming in the Pacific region, it can wreak havoc across large swaths of the world. During the winter months, the western Pacific areas including Australia, Malaysia, and the Philippines have much greater rainfall. Conversely, unusually dry conditions settle in over North America's Gulf Coast and large sections of South and Central America as well. Additionally, in the Canadian and American West, there is a cooling effect. By studying the patterns of the El Niño and La Niña cycles, meteorologists have come to better understand their impacts on global weather phenomena. They are thus better able to make predictions especially in terms of not only the strength of each stage, but also when either will fizzle out or begin again, allowing governments to better prepare for floods and droughts which come with each cycle and to prevent billions of dollars in losses and damage. Thereby, the areas under their influence need accurate forecasts to reduce the wide-reaching effects these phenomena have across many facets of both the environment and the economy.
8. The main purpose in paragraph 4 is to ____
