Recent decades have seen subdued tropical cyclones originating near the Equator, like the 2017 Cyclone Okchi that devastated parts of India and Sri Lanka. A study in Nature Communications suggests a possible increase in these cyclones due to a combination of global warming and the Pacific Decadal Oscillation (PDO), a cyclical event occurring every 20-30 years. Equatorial cyclones were 43% fewer in 1981-2010 than in 1951-1980 due to a warmer PDO phase. The PDO’s interaction with El Niño and La Niña phenomena, collectively known as ENSO, affects India’s rainfall patterns. The study highlights the complex interplay of climate drivers in cyclone formation.
Facts/Terms for UPSC Prelims
- Pacific Decadal Oscillation (PDO): A cyclical climate pattern occurring in the Pacific Ocean every 20-30 years, involving changes in sea surface temperatures. A positive phase correlates with warmer waters in the western Pacific and cooler waters in the eastern Pacific, influencing global climate and weather patterns.
- El Niño Southern Oscillation (ENSO): A recurring climate phenomenon in the Pacific Ocean characterized by El Niño (warmer-than-normal sea surface temperatures) and La Niña (cooler-than-normal temperatures). ENSO affects weather patterns worldwide, impacting rainfall and temperature distributions.
- Equatorial Cyclones: Tropical cyclones originating near the Equator. These cyclones gain intensity from warm waters and moisture, usually forming at a distance from the Equator due to the Coriolis effect. Uncommon, they can cause significant damage due to their intensity.
- Climate Drivers: Factors that influence the Earth’s climate patterns, such as global warming and natural phenomena like ENSO and PDO. These drivers play a crucial role in shaping long-term climate trends and short-term weather events.
- Rainfall Deficits: The difference between the expected and actual amount of rainfall. In the context of India’s rainfall deficits, it refers to the lower-than-normal levels of rainfall, leading to various impacts like drought and water scarcity.