How a warming Pacific Ocean and climate change will impact agriculture

After three consecutive years of cooling (La Niña), the eastern Pacific Ocean surface waters experienced unusual warming (El Niño) in June 2023. Predictive models suggest these conditions will strengthen through the upcoming winter in the northern hemisphere. El Nino’s influence on the summer monsoon and resulting impact on India’s agriculture is a concern.

The Pacific Ocean, covering about one-third of the planet's surface, significantly shapes global climate. This is evident in the variations in ocean-atmospheric conditions known as the El Niño-Southern Oscillation (ENSO).

The ENSO cycle occurs every five to seven years when the central and eastern parts of the tropical Pacific Ocean switch between warm El Niño and cool La Niña. There is also a neutral phase when the waters are near their average temperature.

The impacts of ENSO radiate worldwide. El Niño events profoundly influence extreme weather events such as heatwaves, floods, and droughts, with far-reaching consequences for food production, water availability, and the well-being of people and ecosystems. Predicting ENSO is crucial for generating reliable seasonal forecasts of rainfall and temperature across the globe.

India’s agricultural success relies heavily on the summer monsoon rainfall from June to September. Generally, an El Niño event weakens eastward winds that blow across the Pacific, dampening the Indian monsoon circulation and reducing rainfall over the Indian subcontinent. Historically, at least half El Niño events have been directly linked to droughts during the summer monsoon season. They have amplified temperature rise, heat extremes, and induced more erratic rainfall patterns over the Indian subcontinent.

It is essential to dissect the interplay between climate change, El Niño events, and their combined effects on the future of the monsoon.

El Niño and monsoon onset

This June, India witnessed a weak and delayed monsoon, which is usually the case when an El Niño develops early in the year. The combination of weaker monsoon winds and the warm Arabian Sea set the stage for the formation of cyclone Biparjoy. The cyclone drew moisture away from the monsoon winds, reducing rainfall across the Indian subcontinent during the first three weeks of June. It led to increased convection over sea and caused dry air to sink over India as a compensatory effect. This, coupled with the rainfall deficiency, contributed to heightened temperatures across central and northern regions of India.

In 2015, Chennai in south India experienced an extraordinary rainfall event. The region witnessed its heaviest one-day rainfall in over a century. This event has been attributed partly to the extreme El Niño event between 2014 and 2016. The torrential downpour deprived over three million people of essential services. The heavy rains cost the Indian economy US$ 3 billion. It is a stark reminder of the far-reaching effects that escalating extreme weather events can have on communities and economies.

Most climate models project fluctuations in rainfall related to El Niños will increase significantly in the next few decades. This increase is attributed to the global warming-induced rise in atmospheric moisture content.

El Niño and the future of Indian monsoon

With the oceans absorbing more than 93% of the additional heat from global warming, El Niños are becoming stronger, and therefore also their influence. According to climate models, the connection between El Niño and the Indian summer monsoon will intensify in the coming decades, especially if global carbon emissions remain high. This means the impact of El Niño on the Indian monsoon will become even more pronounced.

The increasing concentration of greenhouse gases in our atmosphere means that relying solely on past climatic conditions to predict the future is insufficient. It is crucial to consider climate model projections when planning long-term adaptation strategies.

Fortunately, several proposed and proven adaptation strategies are available to navigate future challenges.

They include embracing climate-resilient crop varieties and livestock, promoting diverse crop systems, adopting efficient irrigation and water management practices, implementing water and soil moisture conservation methods, along with agroforestry and forestry initiatives to retain soil moisture, prevent erosion, and maintain a healthy ecological balance.

Early warning systems will become more critical as we face increasing uncertainties in weather patterns. These systems can alert farmers about impending extreme weather conditions and provide guidance on potential remedial measures.

The ongoing Agrometeorological Advisory Services led by the India Meteorological Department have already disseminated weather forecasts to farmers through TV, radio, and SMS. It is essential to rapidly expand and scale up these initiatives to reach more farmers and ensure everyone can access necessary weather information.

It is equally important to combine indigenous communities' traditional knowledge with scientific advancements to pave the way for climate-resilient agriculture in India. Integrating both approaches can build a sustainable and resilient future for Indian agriculture.