El Niño and La Niña

El Niño and La Niña Name: ___________________________________________________ Period: ____ Date: ____________ Essential Question: How do El Niño and La Niña affect sea temperature, and weather? Hundreds of years ago, South American fishermen observed that every year around December or Christmas, coastal waters of the Pacific became warmer as a current flowed from north to south. This change often meant a smaller fish catch but more rainfall inland that translated to more abundant crop harvest . They said the current came from El Niño (el NEEN yo) — Spanish for “the boy.” But villagers were not referring to just any boy. Used at this time of year, their term referred to Jesus, “the Christ child.” El Niños can bring heavy rainfall and flooding to the West Coast of South America. Meanwhile, Australia and Southeast Asia may face a drought and high risk of wildfires. In North America, scientists have also linked unusual weather events — including ice storms, droughts and mudslides — to the arrival of an El Niño. Today, researchers use the term El Niño only for those periods when the surface water around the equator in the eastern and central Pacific warms for an extended period of time. Scientists declare the development of an El Niño when they observe a temperature increase of at least 0.4 degree Celsius (0.72 degree Fahrenheit) for five months in a row in the eastern Pacific near the equator. At other times, the surface water in the eastern Pacific instead may cool for long stretches of time. When the average temperature drops by at least 0.4° C (0.72° degree F), climate scientists will announce the arrival of a La Niña (lah NEEN yah). This is Spanish for “the girl.” In general, effects of a La Niña run opposite to those triggered by an El Niño: Now, Central and South America may face severe droughts while Australia floods. Much of the rest of the world, including large portions of Africa and North America, may also see substantial climate impacts from ENSO events. Clarifying Questions: 1. What is El Nino? (Read the chart) El Niño is a climate phenomenon characterized by the periodic warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean _______________________________________________________________________________________ 2. What is La Nina? (Read the chart) La Niña is the counterpart of El Niño, characterized by the periodic cooling of sea surface temperatures in the central and eastern equatorial Pacific Ocean. _______________________________________________________________________________________ 3. What are the GLOBAL EFFECTS OF El Nino? (Read the chart) Changes in precipitation patterns, leading to droughts in some regions and increased rainfall in others. _______________________________________________________________________________________ Disruption of normal weather patterns, affecting agriculture, fisheries, and water resources. _______________________________________________________________________________________ 4. What did South American fishermen observed every year around Christmas in the coastal waters of the South American fishermen observed warmer ocean temperatures and reduced fish catches around Christmas in the coastal waters of the Pacific Pacific?_________________________________________________________________________________ 5. How were the fishermen affected by the warmer current in Pacific that flowed from North to South? The warmer current flowing from North to South in the Pacific during El Niño led to decreased nutrient availability, causing fish populations to decline and _______________________________________________________________________________________ reducing catches for fishermen. 6. How were the farmers affected by the warmer current in Pacific that flowed from North to South? The warmer current during El Niño brought increased rainfall to some regions in South America, benefiting farmers with abundant crops _______________________________________________________________________________________ 7. Why did they call the warming of the equatorial Pacific El Niño? They called the warming of the equatorial Pacific El Niño because it typically occurred around Christmas time and was first recognized by fishermen off _______________________________________________________________________________________ the coast of South America. 8. Why do farmers in South America get abundant crops during El Niño? Think! Farmers in South America get abundant crops during El Niño because the increased rainfall associated with the phenomenon provides favorable _______________________________________________________________________________________ conditions for plant growth. 9. Why do fishermen get less catch during El Niño? Think! Fishermen get less catch during El Niño because the warming of ocean temperatures disrupts the marine ecosystem, reducing the abundance of fish. _______________________________________________________________________________________ 10. How are the following places affected by El Niño? a. West Coast of South America West Coast of South America experiences droughts and reduced fish catches _______________________________________________________________________________________ b. Australia and Southeast Asia Australia and Southeast Asia may face increased rainfall, flooding, and tropical cyclones _______________________________________________________________________________________ c. North America North America may experience milder winters in the northern states and wetter conditions in the southern states _______________________________________________________________________________________ 0.5 degrees 11. El Niño when they observe a temperature increase of at least _____________________Celsius (0.72 five consecutive degree Fahrenheit) for ______________months in a row in the eastern Pacific near the equator _____________________. decreases by at least 12. When the average temperature ________________________________(0.72° degree F), climate the girl scientists will announce the arrival of a La Niña (lah NEEN yah). This is Spanish for “___________.” In opposite general, effects of a La Niña run _________________________________to those triggered by an El Niño: Multiple Choice: Write your answers on the spaces before each number. C ____1. Episodes of ocean warming that affect the eastern tropical Pacific are called A. La Niña B. monsoons C. El Niño B ____2. Strong El Niño events happen every five years. A. True B. False A ____3. Winds are the link between the Southern Oscillation and ocean warming associated with El Niño. A. True B. False A ____4. The trade winds are weaker during an El Niño event. A. True B. False D ____5. Which of the following is a possible condition during an El Niño event? A. drought in Australia C. trade winds weaken B. more rain during the dry season in Florida D. all of the above B ____6. Surface ocean temperatures of the eastern tropical Pacific are colder than average during an El Niño event. A. True B. False B ____7. Some of the heaviest annual precipitation occurs A. over most of Australia B. within the Amazon Basin C. in the Sahara D ____8. The 1997-98 El Niño event was responsible for A. floods from Texas to the Gulf states C. Landslides along the California coast B. significant coastal erosion in California D. all of the above B ____9. The strongest La Niña on record occurred in 1997-1998. A. True B. False A ____10. The warm, humid trade winds converge and produce abundant rainfall in the tropics. A. True B. False