Guwahati: A new scientific study has revealed how climate change, floods and human activity have shaped Majuli Island over the past 4,000 years, offering crucial clues about the future of the world’s largest inhabited river island.
Published in the ‘Review of Palaeobotany and Palynology’, the study conducted by Arya Pandey, Swati Tripathi, Sadhan K. Basumatary, Salman Khan, Biswajeet Thakur, Anupam Sharma, and Hema Singh from the Birbal Sahni Institute of Palaeosciences in collaboration with other organisations, reconstructs long-term monsoon variability and vegetation dynamics using sediment records from the Majuli Island.
By analysing fossil pollen and sediment layers from a 150 cm-deep core, researchers identified five major climate phases dating back to 2090 BCE. The earliest phase, between about 2090 and 310 BCE, indicates warm and humid conditions with dense forests and heavy monsoon rainfall of nearly 3,000 mm annually. Notably, Majuli appears to have remained resilient even during the global 4.2 thousand-year drought event.
Between 310 BCE and 490 CE, vegetation became more open, pointing to relatively drier conditions and fluctuating flood activity. A wetter interval returned between 850 and 1450 CE, corresponding to the Medieval Climatic Anomaly, when deciduous forests expanded and monsoon rainfall strengthened. After 1450 CE, during the Little Ice Age period, cooler and less humid conditions set in. The appearance of cereal pollen and associated weeds suggests expanding human settlement and agriculture on the island.
The study also detected clear signatures of major global climatic events, including the Medieval Climatic Anomaly and the Little Ice Age. Changes in sediment grain size reveal transitions from calm wetland environments to high-energy flood phases, reflecting the dynamic behaviour of the Brahmaputra River. The presence of extra-regional pollen species such as Rhododendron and Castanopsis suggests that episodic floods transported plant material from distant upland regions into Majuli’s wetlands.
Often described as Assam’s cultural capital, Majuli today faces severe riverbank erosion, recurrent floods, deforestation and expanding human settlement. While the long-term climate record shows that the island has endured dramatic swings in monsoon conditions in the past, the researchers caution that modern environmental pressures could reduce its resilience.
They note that high-resolution climate archives from Northeast India are rare, particularly from river islands. By filling this gap, the findings improve understanding of how the Indian Summer Monsoon has varied over millennia — knowledge that is increasingly important as climate change intensifies.
Situated in a sensitive monsoon corridor influenced by both Bay of Bengal moisture and Himalayan air systems, Northeast India has experienced complex and sometimes abrupt shifts in rainfall patterns. The new evidence from Majuli strengthens the case that monsoon behaviour in the region has not always been uniform.
For policymakers and conservation planners, the message is clear: Majuli’s wetlands are not just ecological assets, but valuable climate archives that can help anticipate future risks. As climate variability increases, the history buried beneath the island’s soil may prove vital in safeguarding its future.