El Niño — Reading Comprehension

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Grades

Standards

MS-ESS2-6
MS-ESS3-5

About This Reader

This middle school science passage provides an in-depth exploration of El Niño, the warm phase of the El Niño-Southern Oscillation (ENSO) cycle. Aligned with NGSS standards MS-ESS2-6 and MS-ESS3-5, the text explains the mechanisms that drive El Niño, such as weakened trade winds and changes in Pacific Ocean currents. Students learn about the causes, effects, and global impact of El Niño, including extreme weather events, ecosystem disruptions, and challenges in prediction. Real-world examples from South America, Australia, and North America illustrate the interconnectedness of Earth's systems. The passage includes a glossary, differentiated reading level, Spanish translation, comprehension questions, writing prompts, and graphic organizers. Audio integration supports diverse learners. This resource builds scientific literacy and systems thinking, making it ideal for grades 6-8 classrooms studying climate and Earth’s processes.

CONTENT PREVIEW

ENSO - El Niño-cs — Sea surface is warm in central and eastern Pacific.Less cold water is pulled up along west coast of South America.Hot air rises in central Pacific, travels east and west before cooling and descending. Fred the Oyster, Czech translation Jirka Dl / Wikimedia Commons (Public domain).

El Niño is a climate phenomenon that dramatically alters weather and ocean patterns across the globe. During an El Niño event, regions like Peru and Ecuador experience heavy rainfall and flooding, while places such as Australia and Indonesia face severe droughts. Scientists study El Niño because its powerful effects disrupt ecosystems, food supplies, and even economies worldwide. Understanding the mechanisms behind El Niño helps us predict and prepare for these dramatic changes.

How El Niño Works: The Mechanism

Under normal Pacific Ocean conditions, strong trade winds blow from east to west near the equator. These winds push warm surface water toward the western Pacific, causing it to pile up near Asia. Meanwhile, along the coast of South America, upwelling brings cold, nutrient-rich water to the surface. This process supports thriving fisheries and cools the eastern Pacific. During El Niño, these trade winds weaken or even reverse direction. As a result, the warm surface water spreads back east toward South America. This reduces upwelling and leaves the eastern Pacific ocean warmer than usual. The change in ocean temperatures triggers shifts in atmospheric circulation, altering weather patterns around the world.

Causes, Effects, and Global Interactions

The causes of El Niño are complex and involve interactions between the ocean and atmosphere. Scientists believe that small changes in sea surface temperatures and air pressure can set off a chain reaction, but the exact triggers remain difficult to predict. El Niño events typically last 9 to 12 months and recur every 2 to 7 years. The effects are wide-reaching: Peru and Ecuador may face catastrophic floods, while Australia experiences drought and increased wildfire risk. In North America, El Niño often brings wetter winters to the southern United States and warmer, drier conditions to the north. The phenomenon shifts the jet stream, disrupting typical rainfall and temperature patterns globally. The decline in upwelling along South America reduces fish populations by as much as 50%, impacting both ecosystems and local economies.

Understanding and Predicting El Niño

El Niño is monitored using a network of ocean buoys, satellites, and weather stations that track sea surface temperatures and atmospheric pressure. Scientists analyze data using computer models to make forecasts up to a year in advance, but predicting the precise timing and strength of each event remains a challenge. The study of El Niño highlights the interconnectedness of Earth's systems and the importance of global scientific collaboration. By improving our understanding, we can better prepare for its impacts on agriculture, water resources, and communities worldwide.

In summary, El Niño is a striking example of how changes in one part of the Earth system can ripple across the globe, affecting weather, ecosystems, and societies. Its study continues to advance our knowledge of climate science and the dynamic interactions between the ocean and atmosphere.

Interesting Fact: The name "El Niño" means "The Little Boy" in Spanish, originally referring to the warm ocean current that appeared around Christmas off the coast of Peru.

Which of the following best describes El Niño?

A warm ocean event that changes global weather.A cold ocean current that supports fisheries.A type of hurricane in the Pacific Ocean.A mountain wind that affects local climates.

What usually happens to the trade winds during El Niño?

They weaken or reverse direction.They become stronger.They blow only toward the south.They disappear completely.

How does El Niño affect upwelling along the South American coast?

It reduces upwelling, leading to warmer waters.It increases upwelling and brings cooler waters.It has no effect on upwelling.It causes upwelling only in Australia.

What does the term 'jet stream' refer to in the passage?

A narrow band of fast-moving air high in the atmosphere.A deep ocean current.A wind blowing from the poles to the equator.A type of thunderstorm.

What does 'upwelling' mean as used in the passage?

The movement of cold, nutrient-rich water to the ocean’s surface.The rising of warm air into the atmosphere.The sinking of salt to the bottom of the sea.The melting of polar ice caps.

Which of the following is a likely effect of El Niño in Australia?

Drought and increased wildfire risk.Heavy rainfall and flooding.Cooler than normal winters.Abundant fish populations.

Why is predicting El Niño challenging for scientists?

Its causes are complex and not fully predictable.There is not enough technology to monitor the ocean.Scientists do not study the Pacific Ocean.El Niño only happens once a century.

Which tool is NOT typically used to monitor El Niño?

Deep-sea submersibles.Ocean buoys.Satellites.Weather stations.

True or False: El Niño always makes the eastern Pacific Ocean colder.

TrueFalse

True or False: El Niño events can affect weather patterns all around the world.

TrueFalse