P1B 04El Niño and La Niña Key Concepts and Effects

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What is El Niño?

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A climate pattern that describes the unusual warming of surface waters in the eastern equatorial Pacific Ocean.

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What is La Niña?

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A climate pattern that describes the unusual cooling of surface waters in the eastern equatorial Pacific Ocean. It is the opposite of El Niño.

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What is upwelling?

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The movement of cold, nutrient-rich water from the deep ocean to the surface.

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What are trade winds?

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Prevailing winds that blow from east to west across the tropics. These winds are weakened or reversed during El Niño and strengthened during La Niña.

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What are the effects of El Niño in the Eastern Pacific (Coast of South America - Peru & Ecuador)?

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Low fish catches due to suppressed upwelling of nutrient-rich cold water, economic strain due to reduced fish exports and loss of livelihoods for fishermen, heavy rains and flooding leading to landslides, damage to infrastructure, deaths, and economic strain, sudden bloom of desert flowers in the Atacama Desert, boosting tourism.

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What are the effects of El Niño in the Western Pacific (Australia & Indonesia)?

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Droughts and crop failures (e.g., rice, wheat), severe forest fires due to dry conditions, damaging property and grazing lands, smoke pollution from forest fires affecting human health.

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What are the effects of El Niño in other parts of the world?

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Increased storms along the coast of California, causing coastal erosion and requiring rebuilding of seawalls and structures, food shortages in India and East Africa due to droughts, leading to crop failures, livestock deaths, malnutrition, and starvation risk, global food prices rise.

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What are the effects of La Niña in the Eastern Pacific (Coast of South America - Peru & Chile)?

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Return of nutrient-rich upwelling, leading to higher fish catches and increased exports and income, droughts return to the west coast, causing lower crop production.

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What are the effects of La Niña in the Western Pacific (Australia & Indonesia)?

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Heavier than normal rain and flooding, landslides, especially common in deforested areas of Indonesia.

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What are the effects of La Niña in other parts of the world?

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Increase in diseases like malaria in East Africa due to more stagnant water for mosquito breeding, leading to higher malaria cases and economic strain, end of droughts in Africa and India, resulting in good crop yields and abundant food production.