**Executive Summary**
The Ministry of Science & Technology reports that scientists have found evidence in Raja Rani Lake, Chhattisgarh, indicating India experienced a stronger monsoon between 1,060 and 1,725 CE than previously believed. The research, based on the study of ancient pollen grains in lake sediments, highlights the importance of understanding the Core Monsoon Zone's sensitivity to Indian Summer Monsoon fluctuations for predicting future climate trends. No specific deadlines or action items are indicated.
**Key Points / Main Content**
* **Research Findings:**
* Evidence suggests a stronger Indian monsoon occurred roughly between 1,060 and 1,725 CE.
* The evidence comes from pollen grains preserved in lake sediments of Raja Rani Lake, Korba district, Chhattisgarh, in the Core Monsoon Zone (CMZ).
* The pollen record indicates dominance of moist and dry tropical deciduous forest species suggesting strong monsoon rainfall and a warm, humid climate in central India.
* **Methodology:**
* Researchers extracted a 40-centimeter sediment core from Raja Rani Lake.
* Microscopic pollen grains were identified and counted to reconstruct past vegetation and climate (palynology).
* **Climate Factors:**
* The strong monsoon is attributed to a global warm phase known as the Medieval Climate Anomaly (MCA).
* Contributing factors include La Niña-like conditions, northward movement of the Inter Tropical Convergence Zone (ITCZ), positive temperature anomalies, increased sunspot numbers, and high solar activity.
* **Importance:**
* Understanding vegetation dynamics and hydro-climate variability in the CMZ is crucial for understanding monsoonal variability during the Late Holocene.
* High-resolution palaeoclimatic records generated in this study can help develop paleoclimatic models for simulating future climatic trends and rainfall patterns.
**Impact Analysis**
**Stakeholder:** Climate Scientists / Researchers
* **Impact:** Provides new data and insights into past monsoon patterns and climate variability in the Indian Core Monsoon Zone during the Medieval Climate Anomaly (MCA).
* **Action Required:** Integrate this data into climate models and use it to improve the accuracy of future climate projections.
**Stakeholder:** Policymakers
* **Impact:** Offers high-resolution palaeoclimatic records that can be helpful in developing paleoclimatic models for the simulation of future climatic trends and rainfall patterns.
* **Action Required:** Utilize the research findings for scientifically sound policy planning with a key aspect of societal relevance.
Key Entities Referenced
Indian Summer Monsoon (ISM): A major factor controlling rainfall in India, variations in which are studied using Core Monsoon Zone.
Core Monsoon Zone (CMZ): A region in India where rainfall is primarily controlled by the Indian Summer Monsoon, making it crucial for understanding monsoon variability.
Raja Rani Lake: The location in Chhattisgarh where ancient pollen grains were found, providing evidence about past monsoon patterns.
Department of Science and Technology (DST): The Indian governmental department to which the Birbal Sahni Institute of Palaeosciences (BSIP) is affiliated.
Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow: The research institute that conducted the pollen analysis study, providing the basis for findings on past monsoon intensity.
Ministry of Science & Technology
Ancient pollen hidden below lake tells the story
of a stronger monsoon
प्रव तथ: 12 JAN 2026 6:17PM by PIB Delhi
India may have faced a much stronger monsoon than earlier believed. Scientists have found evidence
of intense rainfall, rain, forests, and climate change roughly between 1,060 and 1,725 CE in central
India hidden in the Raja Rani Lake of Korba district of Chhattisgarh.
Understanding the vegetation dynamics and corresponding hydro-climate variability from the Core
Monsoon Zone (CMZ), wherein the rainfall is essentially controlled by the ISM which contributes to
89 to 90 percent of India’s rainfall, could be crucial in understanding the monsoonal variability during
the Late Holocene (Meghalayan Age) particularly as the CMZ is sensitive to ISM fluctuations.
Scientists from the Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow, an autonomous institute
of the Department of Science and Technology (DST) have found evidence of unusually strong Indian
Summer Monsoon (ISM) in ancient pollen grains preserved in lake sediments in Raja Rani Lake,
Korba district, Chhattisgarh, right in the heart of India’s Core Monsoon Zone (CMZ).
Researchers extracted a 40-centimetre-long sediment core from Raja Rani Lake. The mud records
revealed environmental changes going back about 2,500 years. Within these layers lie microscopic
pollen grains shed by plants that once grew around the lake.
By identifying and counting these pollen grains, a science known as palynology—researchers
reconstructed past vegetation and, in turn, past climate. Forest-loving plants pointed to to warm and
humid conditions, while grasses and herbs suggested drier phases.Fig. 1. (a) Geographical map of India showing the Korba District, Chhattisgarh, CMZ, India (dark black
and bold lines). (b) Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) of the
Korba District (Chhattisgarh), showing the site of investigation (red star).
During the Medieval Climate Anomaly, the pollen record showed a clear dominance of moist and dry
tropical deciduous forest species, indicating strong monsoon rainfall and a warm, humid climate in
central India. Crucially, the study found no evidence of contrasting dry conditions within the Core
Monsoon Zone during this period.
The scientists traced this strong monsoon to a global warm phase known as the Medieval Climate
Anomaly (MCA), roughly between 1,060 and 1,725 CE.
The study attributes the enhanced monsoon to a combination of global and regional factors La Niña–
like conditions, which are typically associated with stronger Indian monsoons, northward movement
of the Inter Tropical Convergence Zone (ITCZ), positive temperature anomalies, increased sunspot
numbers and high solar activity could be driving the climate change and increased ISM during the
MCA.Fig. 2. Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) of India, showing the
regional correlation of MCA in relation to the present study (RRL) (yellow star). Red star shows the MCA
records
This understanding of the Indian Summer Monsoon (ISM) and related climate change variability
during the Holocene could be of immense interest in order to strengthen our understanding of the
present ISM-influenced climatic conditions, as well as of possible future climatic trends and
projections.
Moreover, the high-resolution palaeoclimatic records generated in the present study could be helpful in
developing paleoclimatic models for the simulation of future climatic trends and rainfall patterns and
also for a scientifically sound policy planning with a key aspect of societal relevance.
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