Unpredictable Monsoons in India linked to pollution

The monsoons in India, the lifeblood of the nation's agrarian economy, have become increasingly unpredictable in recent years. This unpredictability is attributed to the combined effects of climate change and pollution. The Indian monsoon provides about 70% of the required rainfall, essential for irrigating farms and replenishing reservoirs and aquifers.

However, increased emissions from the burning of fossil fuels and rising pollution levels are altering monsoon patterns, resulting in adverse impacts on agriculture and posing challenges for accurate forecasting.

Climate change, pollution and monsoon rains

In a laboratory near Hyderabad, Professor Kirti Sahu is conducting pioneering research on raindrops. Along with a team of scientists, Sahu strives to unravel the complex relationship between climate change, pollution and monsoon rains that underpin India's agricultural economy.

Responsible for supplying almost 70% of the country's required rainfall, the Indian monsoon is of paramount importance to India's $3 trillion economy. It dictates the timing of planting, harvesting, and even weddings throughout the country. However, monsoon patterns are being disrupted by climate-altering emissions from burning fossil fuels and rising levels of pollution.

While climate change generally brings more precipitation to wet areas and exacerbates drought in dry regions, the South Asian monsoon has weakened in recent decades. The Intergovernmental Panel on Climate Change (IPCC) attributes this decline to increases in aerosols (tiny particles and liquid droplets in the air) as a result of human activities such as burning fossil fuels, vehicle emissions, dust, and sea salt.

India has long grappled with severe air pollution, with major cities often shrouded in toxic smog. Consequently, the country has seen a shorter and more intense monsoon season, leaving some areas flooded and others parched. Although six major droughts have hit the subcontinent since 2000, they have often caught forecasters by surprise.

Accurate monsoon forecasts are essential for farmers, who rely on them to plan their farming activities. Despite investments in satellites, supercomputers and specialized weather radar stations named after the Hindu rain god Indra, advances in forecast accuracy have been modest. The intricate interplay between climate change impacts and aerosols in India has complicated the task of accurately predicting rainfall patterns.

Unpredictability in distribution of monsoon rainfall

Recent years have witnessed increasing unpredictability in the distribution of monsoon rainfall, characterized by fewer rainy days but heavier downpours. Monsoon clouds have also changed their paths, resulting in excessive rainfall in some states, while others experience historically low rainfall.

These erratic changes have devastating consequences for farmers. Heavy downpours do not allow enough time for plants to absorb the water, leading to a net loss of crops.

Anshu Ogra, an assistant professor specializing in climate change adaptation and disaster risk reduction, stresses the importance of better forecasting to help authorities prepare for extreme weather events and implement effective adaptation strategies, such as collecting rainwater and transporting it to drought-affected regions.

In their quest to improve monsoon forecasts, scientists like Professor Sahu and Thara Prabhakaran are conducting pioneering research. Sahu uses a rain cloud simulator, while Prabhakaran collects crucial data on temperature, pressure and aerosols within clouds from his "flying laboratory" aboard an airplane. Their collaborative efforts contribute to advancing our understanding of how changing conditions affect the monsoon.

Climate Change and Weakening Monsoons

Climate change is causing a series of extreme weather events around the world, with wet regions experiencing increased precipitation and dry regions dealing with more frequent droughts.

The South Asian monsoon experienced a weakening trend in the second half of the 20th century, despite projections of increased rainfall in Asia due to climate change.

The Intergovernmental Panel on Climate Change (IPCC) identifies increases in aerosols (tiny particles and liquid droplets suspended in the air) as a key factor contributing to the decline in the South Asian monsoon. Human activities such as the burning of fossil fuels, vehicle exhaust, dust, and sea salt are responsible for the increased presence of aerosols in the atmosphere.

India has long grappled with high levels of air pollution, particularly in its major cities, which are often mired in toxic smog. The pollution crisis is closely linked to the changing dynamics of the monsoon.

The excessive presence of aerosols, added to greenhouse gas emissions, alters atmospheric conditions and affects the formation of rain clouds. Aerosols can act as cloud condensation nuclei or ice nuclei, influencing cloud properties and precipitation patterns. As a result, the monsoon season has seen a shift towards shorter but more intense rain events, characterized by heavy downpours in limited time periods.

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