El Nino and La Nina – UGC NET Geography Notes

El Nino and La Nina: If you’re preparing for the UGC NET Geography exam, understanding El Nino and La Nina is not optional, it’s essential. These climate phenomena are frequently asked in Paper 2 Geography, often in conceptual, analytical, or match the following formats. Every year, at least 1–2 questions from Climatology or Environmental Geography involve these terms, especially in topics like monsoons, global warming, and ENSO cycles.

Given their direct impact on Indian climate patterns, agricultural productivity, and extreme weather events, mastering El Nino and La Nina not only boosts your score but also enriches your understanding of physical geography in a real-world context.

What is El Nino?

El Nino is a climate pattern that describes the unusual warming of surface waters in the central and eastern tropical Pacific Ocean. It disrupts typical wind and ocean currents, significantly influencing global weather systems.

Key Features of El Nino:

• Abnormal warming of Pacific Ocean waters
• Weakening of trade winds
• Suppression of upwelling near the South American coast
• Often leads to droughts in India and Southeast Asia
• Can cause heavy rainfall and floods in the Americas

What is La Nina?

La Nina is the cool counterpart of El Nino, involving the intensification of cold waters in the central and eastern Pacific Ocean. It strengthens normal weather patterns but can bring its own set of extremes.

Key Features of La Nina:

• Cooling of Pacific Ocean surface waters
• Strengthening of trade winds
• Increased upwelling
• Often causes excess rainfall and floods in India
• May lead to droughts in South America

Difference between El Nino and La Nina

Here is the difference between El Nino and La Nina:

Features	El Nino	La Nina
Ocean Temperature	Warmer than average	Cooler than average
Trade Winds	Weakened	Strengthened
Rainfall in India	Below normal (can cause drought)	Above normal (can cause floods)
Upwelling	Suppressed	Enhanced
Global Impact	Warmer global temperatures	Slight cooling effect globally
Effect on South America	Heavy rainfall and floods	Drought-like conditions

El Nino and La Nina in India

Understanding the role of El Nino and La Nina in India is crucial for UGC NET Geography aspirants, as these two global climate events have a direct influence on the Indian monsoon, which in turn affects agriculture, economy, water resources, and food security. This makes it a highly relevant and frequently tested topic in competitive exams.

How El Nino Affects India?

El Nino leads to the abnormal warming of Pacific Ocean waters, which disrupts the normal flow of trade winds and jet streams. This has the following consequences for India:

• Weak or Deficient Monsoon
  • The Indian Summer Monsoon becomes weaker during El Nino years.
  • Rain-bearing winds from the Indian Ocean are disrupted, reducing rainfall.
  • Regions like Maharashtra, Rajasthan, and Madhya Pradesh are highly vulnerable to drought during El Nino years.
• Agricultural Impact
  • Crop yields fall, especially for rice, pulses, and oilseeds, which are rain-fed.
  • Rural incomes decline due to crop failure, causing food inflation and economic stress.
• Increase in Temperature
  • Higher day and night temperatures.
  • Greater frequency of heatwaves, especially in northern and central India.
• Hydrological Issues
  • Water reservoirs dry up, affecting irrigation and drinking water supply.
  • Hydropower generation takes a hit due to reduced river flows.

How La Nina Affects India?

La Nina, the opposite of El Nino, results in cooler-than-average sea surface temperatures in the Pacific Ocean. This typically strengthens the southwest monsoon in India. Here are some of the affects of La Nina on India:

• Above-Normal Rainfall
  • Stronger monsoon winds bring excess rainfall, especially in the eastern, central, and southern regions.
  • This benefits agricultural output, particularly in rain-fed zones.
• Flooding Risk
  • Excess rainfall in a short period can lead to urban and rural flooding.
  • States like Assam, Bihar, West Bengal, Kerala, and Odisha often report floods during La Nina years.
• Cooler Winter Temperatures
  • La Nina years are associated with colder winters in north and northwest India.
  • Increased likelihood of cold wave conditions in states like Punjab, Haryana, and Uttar Pradesh.
• Positive Agricultural Outlook
  • Timely monsoon onset and retreat improves sowing and harvesting cycles.
  • Enhanced productivity in paddy, sugarcane, cotton, and soybean crops.

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