Climate Records from Tamil Nadu Lake Offer New Insights for Conservation and Biodiversity Planning

New Delhi: Scientists have unearthed one of the most detailed long-term climate records from peninsular India beneath the sediments of Kondagai inland lake on the outskirts of Sivaganga district in Tamil Nadu, a discovery that could significantly strengthen conservation, water management and biodiversity strategies in the region.

The study, conducted by researchers from the Birbal Sahni Institute of Palaeosciences (BSIP), an autonomous institute under the Department of Science and Technology, reconstructs nearly 4,500 years of monsoon behaviour and ecosystem change in inland Tamil Nadu—a region that has so far lacked well-dated, high-resolution lake-based climate records despite its strong sensitivity to the northeast monsoon.

Kondagai Lake lies close to Keeladi, a major archaeological site that has yielded evidence of an advanced urban civilisation from the Sangam period, potentially dating back to the sixth century BCE or earlier. Researchers said the lake’s location within an ancient settlement zone offered a rare opportunity to examine how past monsoon variability, lake ecosystems and human habitation were interlinked over millennia.

To build the record, scientists excavated a sediment profile just over one metre deep and collected 32 closely spaced samples, each representing a distinct time slice. Using a combination of stable isotope analysis, pollen studies, grain-size measurements and radiocarbon dating, the team reconstructed past rainfall patterns, vegetation changes, lake levels and flood events with unusually high precision.

Published in the journal Holocene, the research presents the first high-resolution, multiproxy reconstruction of late Holocene climate and lake-ecosystem dynamics from inland Tamil Nadu. It identifies three major climatic phases over the last 4,500 years, including the 4.2 thousand-year arid event, the 3.2 thousand-year dry phase and the Roman Warm Period. The study establishes direct links between these climatic episodes, monsoon variability, lake hydrology and human activity in the region.

By providing a long-term climatic baseline, the findings are expected to improve regional climate forecasting and help anticipate future droughts, extreme rainfall and flood events in a climate-sensitive state such as Tamil Nadu. Scientists said such historical context is critical for refining monsoon prediction models.

The study also has direct implications for water resource management in drought-prone districts like Sivaganga and Madurai. Insights into past lake-level fluctuations, sediment inflow and hydrological shifts can guide reservoir restoration, groundwater recharge planning, tank rehabilitation and climate-smart agricultural water use in regions heavily dependent on monsoon-fed systems.

From a disaster management perspective, the identification of ancient flood deposits, phases of terrestrial sediment influx and land destabilisation contributes to better risk mapping in the Vaigai basin. Authorities could use these signals to identify areas vulnerable to flooding, channel shifts and land degradation.

The research also adds a valuable dimension to archaeology and heritage studies. By reconstructing the environmental history of Kondagai Lake near the Keeladi settlement, the findings offer clues on how ancient societies adapted to climate variability, water scarcity and ecological stress, strengthening archaeological interpretation and regional heritage conservation planning.

Ecologically, the long-term record of changes in aquatic productivity, oxygen conditions and organic matter sources provides a scientific basis for wetland and lake restoration. Researchers said this evidence-based understanding can help design more effective conservation and biodiversity strategies tailored to the ecological history of the region.