We need a better grasp of our oceanic see-saws

Source: The post is based on the article “We need a better grasp of our oceanic see-saws” published in “Mint” on 27th June 2023.

Syllabus: GS 1 – Indian geography: Monsoon.

News: Accurate predictions of the Indian monsoon remain a challenge. Although the Indian Meteorological Department has forecasted a normal monsoon, a private company called Skymet has predicted a deficient monsoon. To enhance the accuracy of these forecasts, it is crucial to better understand the interplay between El-Nino, the IOD (Indian Ocean Dipole), and climate change.

What is El-Nino and its impact on monsoon?

During an El Nino event, the weakening of tropical trade winds causes warm waters in the Pacific Ocean to flow eastwards, from Asia towards the Americas.

As a result, the coast of the Americas experiences increased heat and low pressure, further aggravating the weakening of the trade winds in a feedback loop. This phenomenon leads to cooler and drier conditions with reduced rainfall in Asia, including India.

An El-Nino was indicated recently by high sea surface temperatures in Eastern Pacific (0.5° C more than the normal). Its probable severity and duration are under study. The estimates must also take into account the effect of global warming.

Data since 1950 reveal a clear link between El-Nino years and droughts in India.

What is IOD and its impact on monsoon?

IOD refers to warmer than usual waters in the western Indian Ocean than in its eastern part. It results in wetter East Africa and drier Indonesia.

Currently, the IOD has been neutral, but experts suggest that it may transition to a positive phase in the upcoming months.

As monsoon winds reach India from south-west, a positive IOD could have aided in rainfall in India and counter the effect of El-Nino.  For example, in 1997, there was an acute El-Nino but due to a highly positive IOD India got excess rainfall.

What should be done?

Understanding the interplay between El Nino, IOD and climate change is crucial as accurate forecasts can have significant implications for agriculture, water resources, and broad economic policy decisions. Therefore, India must invest for a better understanding of factors which impact the monsoon.