Question: What is ENSO? Explain the effects of climate change on El Nino and La Nina phenomenon.
Answer: El Nino Southern Oscillation (ENSO) is a climatic condition that involves the El Nino (hot phase), La Nina (cold phase) and neutral phase. These conditions occur in the tropical waters of the Pacific Ocean between Australia and South America.
Phases under ENSO
- In El Nino, the ocean waters in the Eastern side of the Pacific near the coast of Ecuador become unusually warm.
- The warm surface temperatures create a low pressure system that attracts moisture system towards the region.
- The wind system completely shifts towards Ecuador coast resulting in heavy rains and floods in South America and droughts in South Asia and Australia.
- In La Nina, the ocean waters near the eastern coast of Pacific become unusually colder, in a system exactly opposite to El Nino.
- The western part becomes warmer than the eastern part resulting in shifting of the wind system towards the western part.
- The La Nina condition brings more than usual rains in South Asia, Africa and Australia. There will be droughts in California and South America.
In neutral phase the conditions will be normal. The temperature in oceans will be usual without any particular shift in wind system.
Effects of climate change on El Nino and La Nina
- Reduction in El Nino
As global temperature continues to rise, the ability of the system to maintain heat is lost as warm water evaporates faster as moisture.
- Non-cooling during La Nina
During La Nina, the sea water surface must become cooler than usual. Due to global warming phenomenon, this situation does not take place.
- Increase in moisture
The presence of moisture in atmosphere increases as temperature rises. This alters the balance of the pressure system that forms during El Nino and La Nina.
Thus, the role of El Nino and La Nina in climate stability is immense. Any changes in conditions can lead to their disruption.