A groundbreaking scientific study has reconstructed nearly 4,000 years of climate, vegetation, and flood history of Majuli, the world’s largest inhabited river island in Assam, providing valuable insights that could help communities better adapt to recurring floods and erosion.
Conducted by researchers from the Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow, the study analyzed ancient pollen and sediment samples collected from the Sakali Wetland on Majuli Island. The findings reveal how climate patterns, vegetation cover, and river dynamics have evolved over millennia in one of India’s most ecologically and culturally important regions.
Majuli, situated within the Brahmaputra River system, is renowned for its rich biodiversity and Neo-Vaishnavite cultural heritage. However, the island has been losing land rapidly due to severe riverbank erosion and frequent flooding. Despite these challenges, long term environmental records for the island were previously lacking.
Scientists extracted a 150 centimeter deep sediment core and studied fossil pollen preserved within it. Because pollen grains can survive for thousands of years, they serve as reliable indicators of past environmental conditions. Researchers combined pollen analysis with grain-size studies to understand changes in vegetation, rainfall patterns, river flow, and flood intensity.
The study found that between 4,040 and 2,260 years ago, Majuli experienced a warm and humid climate with dense forest cover. This period suggests the island remained relatively resilient even during the global 4.2-thousand-year climate event, a major phase of drought that affected many ancient civilizations.
The research also identified periods of changing monsoon strength and flood activity over the centuries. Between 1,100 and 500 years ago, the region witnessed relatively moist conditions linked to the Medieval Climatic Anomaly, a period known for warmer temperatures in several parts of the world. Over the last 500 years, however, temperatures and rainfall gradually declined, corresponding with the Little Ice Age. During this time, evidence of increased human influence on the landscape also emerged.