The monsoon rains that batter India each summer, unleashing 80% of the country’s yearly rainfall in four months crucial for its farmers, are at the whim of forces far beyond its borders.

The first study, a paper published in the journal Earth-Science Reviews in April, found that dust particles swept into the atmosphere from deserts in the Middle East grow so hot under sunlight that they change the air pressure over the Arabian Sea. This creates a kind of heat pump in the sky, which drives moisture from above the ocean to the Indian subcontinent, leading to a wetter monsoon season that then strengthens winds and could whip up even more dust particles.

Deepti Singh.

The study finds that “even with modest warming projected under the low-emission trajectories, the monsoons are likely to intensify,” said Deepti Singh, an assistant professor in the School of the Environment at Washington State University Vancouver. “One of the key findings is that these latest climate models project even more pronounced intensification of the monsoon.”

While most studies agree that these dust aerosols strengthen the Indian summer monsoon, their estimates of how and where rain is likely to fall vary widely, according to the new Earth-Science Reviews paper on dust in the Mideast.

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