Loading…
Scientists have reconstructed about 25,000 years of South Asian monsoon variability from magnetic minerals in sediments beneath Bakhira Lake in Uttar Pradesh.
The work was carried out by the Birbal Sahni Institute of Palaeosciences, an autonomous institute of the Department of Science and Technology, and published in Palaeogeography, Palaeoclimatology, Palaeoecology.
The chronology rests on seven accelerator mass spectrometry radiocarbon dates, and the record spans the Last Glacial Maximum, Heinrich Stadial 1 and the Holocene Climatic Optimum.
Bakhira is a perennial oxbow and floodplain wetland of the Ghaghara-Rapti alluvial system, formed when the Rapti river cut off a meander loop.
One of Uttar Pradesh's largest wetlands, it was designated a Ramsar site in 2022 and is an important wintering ground for waterfowl.
A meandering river erodes the outer bank of a loop until the neck is breached; the river then takes the shorter course and abandons the loop, which survives as a crescent-shaped lake. These lakes are shallow, nutrient-rich and slowly silt up.
Simple Analogy: The river straightens its path and leaves the old bend behind, like a discarded loop of rope.
Autonomous research institute of the Department of Science and Technology working on palaeobotany, palaeoclimate and palaeoenvironment reconstruction
Parent department funding BSIP and India's climate-science research programmes
Intergovernmental treaty adopted in 1971 for conservation and wise use of wetlands; India joined in 1982 and Bakhira was listed in 2022
Bakhira lies in the Central Ganga Plain in eastern Uttar Pradesh, within the alluvial tract built by the Ghaghara and its tributary the Rapti, both of which rise in Nepal and join the Ganga system.
GS Paper I > Geography — landforms, monsoon; GS Paper III > Conservation and climate science
General Awareness > Geography and environment
The study of magnetic minerals in sediments and soils as proxies for past climate, weathering and erosion
Accelerator mass spectrometry dating that counts carbon-14 atoms directly, allowing very small samples to be dated precisely
The period around 26,000-19,000 years ago when global ice sheets reached their greatest extent and the monsoon was weak