A new study has established a surprising connection between the early evolution of the Indian monsoon and the formation of ice sheets in Antarctica.

Published in Palaeogeography, Palaeoclimatology, Palaeoecology, the research shows that the onset of Antarctic glaciation 34 million years ago reshaped global rainfall patterns, triggering heavy monsoon rains in what is now Northeastern India.

The clue came from a fossil leaf preserved in the Laisong Formation of Nagaland. Using the Climate Leaf Analysis Multivariate Program (CLAMP), scientists reconstructed past climates by analysing the size, shape, and structure of the leaf. The findings revealed that Nagaland once had a warm and wet climate, much wetter than today.

The team, led by researchers from the Birbal Sahni Institute of Palaeosciences in Lucknow and Dehradun’s Wadia Institute of Himalayan Geology, found that the growth of Antarctic ice shifted the Intertropical Convergence Zone (ITCZ), Earth’s primary rain belt, toward the tropics.

This change intensified rainfall in India’s northeast while altering global wind and precipitation systems.

The results align with the global timing of Antarctic glaciation, directly linking polar ice growth to tropical monsoons.

The study also offers lessons for the present. Today, shifts in the ITCZ are driving erratic monsoon patterns across South Asia. In 2024, western India received unusually high rainfall while the northeast stayed relatively dry, mirroring the ITCZ’s southward movement. Similar extremes have struck Pakistan and China.

Since millions in India depend on rain-fed farming, such changes increase the risk of both droughts and floods.

Researchers say the study highlights how deeply interconnected Earth’s climate is. Events at the poles can dramatically alter life in the tropics. Understanding these ancient shifts, they argue, can help prepare for the challenges of today’s climate crisis.

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