Explainer: Why El Nino is a concern for Indian monsoon rains?

India's weather office has forecast normal monsoon rainfall in 2023. However, a 90 per cent likelihood of an El Nino weather pattern developing during the June-September monsoon season raises the possibility of less than normal rain.

In the past, India has experienced below-average rainfall during most El Nino years, sometimes leading to severe drought that destroyed crops and forced authorities to limit the export of some food grains.

What is El Nino? How does it affect India's monsoon?

El Nino is a weather phenomenon that occurs when ocean temperatures in the central and eastern Pacific Ocean rise above normal. The warming causes changes in atmospheric patterns, leading to a weakening of the monsoon circulation over the Indian subcontinent. As a result, the Indian monsoon tends to be weaker and less reliable during El Nino years.

Hw close is the correlation between El Nino and monsoon rain?

The correlation between El Nino and Indian monsoon rainfall is significant, despite occasional instances when India gets normal or above-normal rain during El Nino years. Over the past seven decades, the El Nino weather pattern occurred 15 times, with India experiencing normal or above-normal rainfall in six instances. However, a contrasting trend has emerged in the last four El Nino years, with India consistently facing drought conditions and rainfall falling below 90 per cent of the long period average.

El Nino events are categorised according to the magnitude of temperature rise above normal, as weak, medium or strong.

In 2009, a weak El Nino led to a significant reduction in India's rainfall, plummeting to 78.2 per cent of normal, the lowest recorded in 37 years. Conversely, in 1997, a strong El Nino occurred, yet India received 102 per cent of its normal rainfall. Weather models are suggesting 2023 El Nino could be strong.

Why is the monsoon important?

The monsoon is vital for India, providing about 70 per cent of annual rain and impacting key crops such as rice, wheat, sugarcane, soybeans, and peanuts. Agriculture contributes about 19 per cent to India's $3 trillion economy and employs more than half of the 1.4 billion population.

Good rainfall will lift farmers' incomes and help to keep a check on inflation. Drought could add to anti-incumbency sentiment.