**Policy Summary:**
A study published on September 9, 2025, by the Press Information Bureau (PIB) Delhi, details research connecting the formation of Antarctica approximately 34 million years ago with the early evolution of the Indian monsoon system. The research, led by scientists from the Birbal Sahni Institute of Palaeosciences Lucknow and the Wadia Institute of Himalayan Geology Dehradun (autonomous institutes of the Department of Science and Technology (DST)), analyzed well-preserved fossil leaves from the Laisong Formation in Nagaland.
The analysis, utilizing the Climate Leaf Analysis Multivariate Program (CLAMP), revealed that Nagaland experienced significantly warmer and wetter conditions during that period. The timing of these conditions coincided with the initial formation of massive ice sheets in Antarctica. The research suggests that the growth of Antarctic ice shifted the Intertropical Convergence Zone (ITCZ), a major rain belt, from the South Pole towards the tropics. This shift resulted in exceptionally high rainfall and temperatures in India, driving the evolution of the Indian monsoon system.
The study, published in *Palaeogeography, Palaeoclimatology, Palaeoecology*, underscores the interconnectedness of global climate systems. The findings suggest that modern climate change, which is accelerating Antarctic ice melt, could potentially shift the ITCZ again, disrupting rainfall patterns across the tropics, with potentially profound consequences for India's monsoon-dependent agriculture, water supply, and livelihoods. The research emphasizes the importance of understanding past climate shifts to better prepare for future climate challenges. Release ID: 2164981.
Key Entities Referenced
Nagaland: A state in Northeast India where fossil leaves were discovered, providing evidence of past climate conditions.
Antarctica: The continent whose formation and ice sheet growth 34 million years ago is linked to the evolution of the Indian monsoon system.
Indian Monsoon System: The rainfall pattern in India that was significantly impacted by the formation of Antarctica and the shift of the Intertropical Convergence Zone (ITCZ).
Laisong Formation: The geological formation in Nagaland where the fossil leaves, used for climate reconstruction, were found.
Birbal Sahni Institute of Palaeosciences Lucknow: An autonomous research institute that led the study on fossil leaves and climate reconstruction.
Wadia Institute of Himalayan Geology Dehradun: An autonomous research institute that collaborated on the study of fossil leaves and climate reconstruction.
Department of Science and Technology DST: The government department to which the Birbal Sahni Institute and Wadia Institute are affiliated.
Intertropical Convergence Zone ITCZ: A major rain belt whose shift due to Antarctic ice growth impacted rainfall patterns in India.
Ministry of Science & Technology
Fossil leaves from Nagaland reveal how Antarctica
shaped the Indian Monsoons
Posted On: 09 SEP 2025 5:20PM by PIB Delhi
A new study has established a connection between the formation of Antarctica around 34 million
years ago and the early evolution of the Indian monsoon system that allowed lush forests to flourish
across the subcontinent.
The discovery of well-preserved fossil leaves from the Laisong Formation in Nagaland, dating back about 34
million years, suggested that the region once had a warm and wet climate.
This led scientists from led by researchers from the Birbal Sahni Institute of Palaeosciences (Lucknow) and
Wadia Institute of Himalayan Geology (Dehradun), both autonomous institutes of the Department of Science
and Technology (DST) to carry out a detailed climate reconstruction and the results revealed something even
more striking—very high rainfall and temperatures. The scientists started exploring what could have caused
such extreme tropical conditions at that time.
They found the clue lay in the fossil’s age, which matched the period when massive ice sheets first began
forming in Antarctica. This timing pointed to a global connection—suggesting that the growth of Antarctic ice
may have shifted wind and rainfall patterns, bringing intense monsoonal rains to Northeast India.
Fig 1 Locality in Nagaland (marked by star) from where the fossil leaves were collected
Their research published in Palaeogeography, Palaeoclimatology, Palaeoecology revealed that the growth of
Antarctic ice reshaped global wind and rainfall patterns by shifting the Intertropical Convergence Zone
(ITCZ)—a major rain belt—from the South Pole toward the tropics. As a result, India experienced
exceptionally higher rainfall and warmer temperatures and the resultant evolution of the India monsoon
system.
To uncover this story, scientists turned to an unusual witness: fossilized leaves found in the hills ofNagaland. Using a method called CLAMP (Climate Leaf Analysis Multivariate Program),
researchers reconstructed past climates by studying the size, shape, and structure of these ancient
leaves. Their findings showed that Nagaland once experienced much wetter and warmer conditions
than today. Strikingly, these results matched the global timing of Antarctic glaciation—linking ice
growth at the South Pole with tropical rainfall in India.
Fig 2 Fossil leaves collected from the Nagaland belonging to ~34 Million-year age used in the study
This discovery is more than just a tale of Earth’s deep past. It carries a warning for our future. As modern
climate change accelerates Antarctic ice melt, the ITCZ may shift again, disrupting rainfall across the tropics.
For India and its neighbors, this could mean profound changes in the monsoon—the lifeline for agriculture,
water supply, and millions of people’s daily lives.
The study highlights that Earth’s climate is a global web. What happens in one corner of the
world—be it the icy deserts of Antarctica or the humid forests of Nagaland—can reverberate across
continents. By learning how our planet responded to dramatic shifts millions of years ago, we can
better prepare for the challenges looming in a warming future.
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NKR/PSM
(Release ID: 2164981)