Issue Overview: El Nino and La Nina

Issue Overview: El Nino and La Nina By Bloomberg, adapted by Newsela staff on 09.28.16 Word Count 748 TOP: A Category 5 typhoon in the Pacific Ocean. BOTTOM: Graphics courtesy of the U.S. National Oceanic and Atmospheric Administration (NOAA). When the Pacific Ocean around the equator gets just a little warmer, terrible things can happen. Thousands of people around the world could die as the weather changes dramatically. Some countries may also lose a lot of money. The weather destroys precious crops. Prices of goods, ranging from nickel to coffee, will rise. The countries that normally buy these products can no longer afford them. The countries that sell them will therefore no longer get paid. Then, when the waters cool, the patterns shift. Areas that were previously spared could experience devastating hurricanes, floods or drought. This cycle changes the damaging effects from one place to another based on the stage it's in. The whole cycle is known as El Nino-Southern Oscillation. It is made up of El Nino, the Pacific's warm stage; La Nina, the cold stage; and a middle stage between the two. This cycle tends to happen every two to seven years.

The Situation An El Nino stage can last a very long time; for example, the U.S. declared one in March 2015 that was not over until June 2016. Both the Australian and U.S. weather agencies are now watching out for La Nina. The U.S. thinks La Nina could develop between July and August. The latest El Nino was the strongest since the record event of 1997-98. It was blamed for making 2015 the hottest recorded year. Officials think even the cooling from a La Nina stage will not prevent another record this year. El Nino reduced rainfall in the Indian monsoon, drying up farmlands. It also reduced crops of cocoa in Ivory Coast, rice in Thailand and coffee in Indonesia. La Nina could help that dryness. But it probably won't come in time to completely undo the conditions that El Nino brought.

The Background Fishermen in Peru named El Nino in the 1600s. They noticed that on some years the tropical Paciﬁc warmed up around Christmas. Since Christmas is known in the Bible as the day Christ was born, the ﬁshermen decided to name this change in the weather El Nino, the Spanish word for child.

El Ninos happen when there s a weakening in the trade winds. These are the winds the blow in opposite directions along the equator. Their motion pushes the sun-warmed waters of the equatorial Pacific to gather in the west. Some of that water then flows back east, making the eastern Pacific hotter. This unusual event affects larger wind currents, moving storms from place to place. After El Nino's heat, the ocean begins to cool. Initially, the Pacific falls into a state between the hot and cold stages. The cooling continues and sea surface temperatures fall below normal. This is when La Nina occurs. After a strong El Nino stage, the Pacific often goes through a short in-between stage. It then snaps quickly into La Nina. This also happens in the Atlantic and Indian oceans, but the effects here are not as dramatic as in the Pacific. El Nino's effects are enormous. A strong El Nino phase can increase the length of a day by about a millisecond. This is because it slightly slows the Earth s rotation. The 1997-98 El Nino is blamed for an estimated 23,000 deaths. It also caused $33 billion in property damage. Scientists argued in a 2011 paper that the El Nino-Southern Oscillation cycle may have even played a part in big political problems that took place from 1950 to 2004.

The Argument Scientists have argued about the effects of El Nino since the late 1990s. They wonder if El Ninos are becoming stronger and more frequent because of global warming. Global warming is the world's increased temperature from human activity. It is happening because, among other things, many of our factories and technologies release carbon dioxide into the air.

In 2013, evidence showed that El Ninos had become stronger and that climate change may have played a part. Another study predicted a doubling of extreme El Ninos because of global warming. There are so many things that affect El Nino. Because of this, understanding what role global warming plays by itself may not be possible. One U.S. government meteorologist said there is evidence that El Ninos will grow more common, and stronger. Yet, he said there is evidence to support the opposite view too. If El Ninos do become stronger, experts say the effect on humans can still be reduced. We can do this by improving weather forecasting and disaster preparations.

Quiz 1 Based on the section "The Argument," which statement is TRUE? Global warming is not related to El Ninos. Some scientists believe that global warming makes El Ninos stronger. The U.S. government will hire more meteorologists to study El Ninos. El Ninos are becoming weaker because of global warming. 2 Based on the article, which sentence best explains the relationship between El Nino and La Nina? El Nino cools the waters of the Pacific Ocean and La Nina heats them back up again. El Nino happens in the Pacific Ocean immediately after La Nina happens in the Pacific Ocean. El Nino is the warming of the Pacific Ocean and La Nina is the cooling of the Pacific Ocean. El Nino causes strong winds to happen in the Pacific Ocean and these winds cause La Nina. 3 Based on information in the article and the graphic "Weather Impacts of El Nino," how does El Nino affect the world at different times of the year? El Nino causes more places in the world to be warm during the winter months than during the summer months. El Nino affects the weather of more places in the world during the summer months than in the winter months. El Nino causes more places in the world to be dry and cool in the winter months than in the summer months. El Nino creates more floods in the world during the winter months than during the summer months.

4 Based on the two graphics, which sentence describes a difference between the weather impacts of El Nino and those of La Nina during December through February? El Nino causes some dry and cool weather during December through February; La Nina causes no dry and cool weather during that time. El Nino causes very warm weather in some places during December through February; La Nina causes cool weather in only one place during that time. El Nino causes wet and warm weather over the Pacific Ocean during that time; La Nina causes dry and cool weather over the Pacific Ocean during that time. El Nino causes mostly dry weather during December through February; La Nina causes no dry weather anywhere during that time.

Answer Key 1 Based on the section "The Argument," which statement is TRUE? Global warming is not related to El Ninos. Some scientists believe that global warming makes El Ninos stronger. The U.S. government will hire more meteorologists to study El Ninos. El Ninos are becoming weaker because of global warming. 2 Based on the article, which sentence best explains the relationship between El Nino and La Nina? El Nino cools the waters of the Pacific Ocean and La Nina heats them back up again. El Nino happens in the Pacific Ocean immediately after La Nina happens in the Pacific Ocean. El Nino is the warming of the Pacific Ocean and La Nina is the cooling of the Pacific Ocean. El Nino causes strong winds to happen in the Pacific Ocean and these winds cause La Nina. 3 Based on information in the article and the graphic "Weather Impacts of El Nino," how does El Nino affect the world at different times of the year? El Nino causes more places in the world to be warm during the winter months than during the summer months. El Nino affects the weather of more places in the world during the summer months than in the winter months. El Nino causes more places in the world to be dry and cool in the winter months than in the summer months. El Nino creates more floods in the world during the winter months than during the summer months.