BY:-Shruti Priya(14CS0055)

El Nino Impact on Climate Change

What is El Nino?

• El Nino is the name given to a southerly, warm ocean current off the coast of Ecuador is a Spanish term “the Christ child”, so called as it generally occurs after Christmas.

• El Nino is a naturally occurring event in the equatorial region which causes temporary changes in the world climate.

• It is not a regular event.• The average period length is five years.

What is ENSO?

• ENSO is the "El Nino-Southern Oscillation,". The Southern Oscillation is a see-saw shift in surface air pressure between the eastern and western halves of the Pacific. When pressure rises in the east, it falls in the west and vice versa. In the 1950's scientists realized that El Nino and the Southern Oscillation were parts of the same event.

The ENSO Cycle• Naturally occurring phenomenon.• Equatorial Pacific fluctuates between warmer than average

(El Nino ) and colder than average (La Nina) condition.• The changes in SSTs(Sea surface temperature) affect the

distribution of tropical rainfall.• Changes in intensity and position of jet streams and storm

activity occur at higher latitudes

• Naturally occurring phenomenonNaturally occurring occurring phenomenon

The first signs of an El Nino• A rise in air pressure in the Indian Ocean,

Indonesia,and Australia.• A fall in air pressure over Tahiti and rest of the

central and eastern Pacific Ocean.• Warm air rises in Peru.• The trade winds in the south Pacific or hard east

Normal year

• In normal years,Eastern winds push the warm surface waters westwards across equtorial south pacific,causing warm surface water to accumulate near Indonesia.

• This helps in the formation of clouds,which give heavy rainfall in North Australia.

• Cold current carries oxygen & nutrients that sustain fish.

Normal year

El Nino year

• El Nino years,Easterly winds even reverse.Warm surface water flows from west to east,increasing the depth of warm water off the South American coast.

• Heavy rainfall due to warm water.• warm water suppresses the nutrient-rich Peru

current• Fish & seabirds move away or die.

El Nino year

• Increased precipitation over parts of South America,western and southern U.S.

• Severe flooding.• Drought in Australia,Indonesia,phillipenes.• Reduction in annual monsoons in India.• Severe crop damage.

Effects of El Nino

Chennai flood

Impact of El Nino on India

• Dry conditions and deficient monsoon.• Alter the climate.• Development of warm conditions.• It will result drought /heavy rainfall situation.• It reduces the production of summer crop.

Indian monsoon

• ENSO-induced warm zones in the Pacific cause the warm air over them to rise and initiate circulation cells. Such cells along northern Australia, Indonesia and the eastern edge of the Indian Ocean could have their downdraft sides over a nascent monsoon circulation cell in the Indian Ocean, which would disrupt its formation, causing poor monsoon rains over the subcontinent. This model implies that El Nino years should coincide with deficient monsoon rains.

Records of El Nino

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