Global Climate Change – The KGP Chronicle

IIT Kharagpur discovers Isotopes in Fossil Trees from Deccan Trap Lavas that Indicate Wetter Future Due to Global Warming

Deccan Trap lava hills in Western Ghats (Left) and columnar basaltic lavas (Right) which erupted 66 million years back killing dinosaurs and most life on earth.

A team of scientists from IIT Kharagpur and Academia Sinica, Taipei have indeed found evidence of triple oxygen isotopes of intertrappean fossil woods that led to very high annual rainfall during the catastrophic volcanism of Deccan trap that erupted in India about 66 million years back. The eruption drove a major mass extinction killing nearly 80% of all species of animals including the Dinosaurs. The depleted values of the oxygen isotopes suggest a higher tropical rainfall (1600 mm/y) in island India during terminal Cretaceous period. The increase in rainfall and its waning in the early Palaeocene closely follows change in palaeo-atmospheric pCO2 suggesting a possible underlying link. The inferred rainfall increase is consistent with modern climate models and palaeobotanical evidence.

Prof. Anindya Sarkar
Department of Geology and Geophysics
IIT Kharagpur

“The available records of the atmospheric CO₂ concentration and temperature over both land and ocean during the time of Deccan Trap eruption were analyzed. This was a period of cataclysm. All around the central and western India, Deccan trap lavas were erupting spewing huge amount of CO₂ from deep interior of the earth thus increasing the then atmospheric CO₂ concentration to as high as 1000 ppm (parts per million). The land and ocean temperatures increased by ~13°C and ~4°C respectively. It was a hot earth and unbearable for life. The rainfall, both before and after this high CO₂concentrated earth was just as normal as today. This was an ancient analogue of what our future greenhouse earth could be,” said IIT Kharagpur’s Prof. Anindya Sarkar of Geology and Geophysics who led the research.

Fossil fuel emission has increased the CO₂ from pre‐industrial level of 280 ppm to ~420 ppm in 2023. Climate models suggest that a doubling of CO₂ will intensify the atmospheric circulation and consequently the rainfall. Many experts, however, believe that the climate change due to such fast rate of global warming is now irreversible and another mass extinction is just imminent, added Prof. Sarkar.

66 million year old fossil trees from the lake sediments within Deccan lava flows and microscopic photograph of vascular bundles in palm tree (left), and Scanning electron microscopic image of the cellular structures of fossil palm trees (right)

The 2023 AR6 report by the Intergovernmental Panel on Climate Change (IPCC) warns if the CO₂ emission and global warming continues unabated, annual wettest day precipitation will increase by manifold across all continents. Monsoonal precipitation associated with tropical cyclones over India will also increase by 40%. While these predictions are made through climate models, they can only be tested by studying the rainfall record in the past when the earth went through natural warming phase due to high CO₂ emission.

The laser ablation system developed at IIT Kharagpur capable of analyzing ultra‐low quantity of rare isotopes of oxygen in silicate phases (shown by arrow)

“Deccan Traps are one of the most voluminous basaltic volcanic lavas erupted on Earth covering over 500,000 sq. km of the west‐central Indian subcontinent. We retrieved the past rainfall by analyzing oxygen isotopes in fossilized trees those grew around the lakes formed over the basaltic lavas of Deccan traps. It was as if an ancient forest was fossilized. These lakes were formed during the quiescent period between two successive lava flows. Known as intertrappeans, the sediments in these lakes contain abundant plant, frog and fish fossils. The trees were exceptionally well preserved and buried immediately after they fell in lake beds making them robust climate recorder,” added Prof. Sarkar.

Prof. Mao Chang Liang
Academia Sinica

“We studied very high magnification images of several palm trees from these lake sediments and found that their internal cellular structures are preserved just like modern trees,” said collaborator Prof. Mao Chang Liang from Academia Sinica.

There is considerable debate about the effect of future global warming on tropical precipitation. Interpretations from the global climate models differ due to an inadequate understanding of the processes controlling rainfall and associated feedback. The robustness of the predictions is also limited due to the lack of deep time data of precipitation in a high CO2 and warmer globe that existed in the geological past.

Sangbaran Ghoshmaulik
Ph.D Student
IIT Kharagpur

“Getting information about the past rainfall is tricky. We used a very novel and new technique of Laser beam as well as NanoSIMS (Nanoscale Secondary Ion Mass Spectrometry) where the fossil trees were analyzed for all the three isotopes of oxygen namely, 16,17, and 18. The isotopes in the fossil trees record the isotopic composition of the lake water derived from rainfall. Analyzing isotopes of mass 17 is difficult since it occurs in extremely small quantity in natural materials. Globally there are only three or four laboratories those can reliably do this job. It took nearly four years for us to develop this method but once done the results were very startling” said Sangbaran Ghoshmaulik, a Ph.D student at IIT Kharagpur and the lead author of the paper.

The Cretaceous period represents an example of hot deep sea and land temperatures often exceeding 10 °C and 30 °C respectively and high CO2 earth. The intertrappean sediments deposited during the voluminous basaltic outpouring of end-Cretaceous Deccan volcanism in India provide a unique repository to infer the magnitude of tropical precipitation during an enhanced greenhouse period.

Prof. Sourendra Bhattacharya
Co‐author of the Paper
IIT Kharagpur

“Excepting the arid/semi‐arid regions, the modern annual rainfall over large part of peninsular India on an average is about 1000‐1200 mm. Our data suggested that these fossil trees recorded 1800‐1900 mm/year rainfall. This is exactly what the IPCC predicts in case of a future extreme 4^oC warming of the planet,” said Prof. Sourendra Bhattacharya, a co‐author of the paper. The study has just been published online in prestigious Elsevier Journal Chemical Geology.

Link of the paper:
https://www.sciencedirect.com/science/article/abs/pii/S0009254123002991

Media Coverage :

Times of India	The Hindu
Ananda Bazar Patrika	UNI
Outlook India	Dainik Jagran

Sunday Times

Dainik Jagran

Contact person : Prof. Anindya Sarkar, Department of Geology and Geophysics, IIT Kharagpur
Email: sarkaranindya@hotmail.com

Edited By : Poulami Mondal, Digital & Creative Media Executive (Creative Writer)
Email: poulami.mondal@iitkgp.ac.in, media@iitkgp.ac.in, Ph. No.: +91-3222-282007

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A Study on Rising Atmospheric Pollution in Rural India

Researchers from Indian Institute of Technology (IIT) Kharagpur have found increasing atmospheric pollution in rural India using Nitrogen Dioxide (NO2) measurements from satellites. Prof. Jayanarayanan Kuttippurath and Research Scholar Mansi Pathak of Centre for Ocean, River, Atmosphere and Land Sciences (CORAL) of IIT Kharagpur analysed the significant impact of urban pollution on the air quality of rural India by differentiating the pollution in two zones – rural and urban – and assessing the extent of air pollution in rural India. The researchers found that air pollution is not typically an urban phenomenon but can also affects the environment in rural perimeter. They conducted an analysis of the rural air quality to assess the extent of air pollution by measurements of NO2 through satellite imaging. The analysis carefully delineates the rural and urban regions of India, to examine the unheeded rural air pollution. Most air pollution assessments till date, discussed only the urban air quality issues. This analysis exposes increasing trends (0.05–0.44×10¹⁵molec./cm²/yr) of NO₂ in the rural regions of India.

The study titled “Air Quality Trends in Rural India: Analysis of NO2 Pollution using Satellite Measurements,” highlights that rural sources account for 41 per cent of the overall NO2 pollution in India of which 45 per cent and 40 per cent are from transportation and power sectors, respectively. As the sources of NO2 are well coupled to the industrial and economic upliftment of a nation, the analyses for the rural regions show distinct seasonal changes with the highest value (2.0 1015 molecules per cm2) in winter and the lowest in monsoon (1.5 1015 molecules per cm2) seasons.

Prof. Jayanarayanan Kuttippurath
CORAL
IIT Kharagpur

“What we observe is that there is a decline in air quality in rural India in terms of our NO2 analysis, which is not beyond the threshold levels now, except in regions such as Delhi and suburbs and eastern India. However, given the positive trend in NO2 concentration, the high rate of urbanization and relocation of industries to suburbs, growing population and development activities, other regions of India would also cross the pollution threshold to impact the health of its people, and thus, our massive rural population. This is the real concern and it is the right time to take appropriate actions to control the atmospheric pollution in rural India,” explained Prof. Jayanarayanan Kuttippurath of CORAL, IIT Kharagpur.

Air pollution is one of the biggest problems in India’s major cities. Comparison of pollutant-wise highest health risk values show that NO₂ is about 19 times more harmful than Particulate Matter (PM) and about 25 times more risky than that of Sulphur Dioxide (SO_{2) .}The population residing in the regions of high NO₂ such as in the proximity of power plants, industries, cities, and in the areas above the permissible limit, are prone to be at high risk of adverse health effects such as asthma, bronchitis, pneumonia and cardiovascular diseases.

Ms. Mansi Pathak
Research Scholar
IIT Kharagpur

Research Scholar, IIT Kharagpur and lead author of the paper, Ms. Mansi Pathak, stated, “We usually think the atmospheric pollution exists only in cities or it is just an urban threat. The air quality standards in rural regions are often neglected. However, our analysis suggests that it is high time to shift our focus to rural regions and examine the pollution levels and health issues of rural India. This is of paramount importance for a country like India, as rural areas have about 67 per cent of the country’s population (947 million) as of 2020 and public health today stands out to be the utmost priority globally.”

The indirect impact of NO2 on global climate change is not less with a net cooling effect attributed to the oxidation-fueled aerosol production.

Figure: The average concentration and long-term trends in atmospheric NO₂ in India for the period 1997-2019.

High Nitrogen Oxide (NO) – which includes Nitric Oxide and Nitrogen Dioxide – levels in the troposphere can alter ozone formation, contribute to nitrate aerosol formation and acid deposition and affect regional climate.

Prof. Kuttippurath said though, other Indian rural regions are under permissible limits of CPCB, the increasing trends in NO2 would surpass the standards in future if no controlling measures are implemented, which is a serious concern.

This study suggests the need for taking action towards improving rural air quality to reduce the impact of air pollution on the large rural population of India. Although NO₂ is a non-abundant gas, its indirect impact on global climate change is likely to be greater, with a net cooling effect attributed to the oxidation-fueled aerosol production. NO_x levels in the troposphere can alter ozone formation, contribute to nitrate aerosol formation, and acid deposition and affect regional climate. The regions covered in this study are Indo-Gangetic plain, Central India, North-West India, Peninsular India, Hilly Region and North-East India where the authors analysed atmospheric NO2 concentration in different regions of India for the period 1997-2019.

Figure: Rural and urban atmospheric NO₂concentration in different regions of India for the period 1997–2019.

“Regulations similar to the Bharat Stage norms (for limiting vehicular emissions) need to be implemented in thermal power plants and industries located in both rural and urban regions, to restrict the overall NO2 pollution in rural India. Introducing new natural gas-fed power plants or using selective catalytic reduction (SCR) in older power plants can also reduce emissions, and thus, the NO2 pollution in rural India,” pointed out the researchers.

Publication Links: https://doi.org/10.1039/D2EM00293K

Media Coverage:

PTI	UNI	Indian Express
Economic Times	Dainik Jagran	Business Standard
The Print	IBC 24	Neo Science Hub

Contact Person: Prof. Jayanarayanan Kuttippurath of CORAL, IIT Kharagpur
Email: jayan@coral.iitkgp.ac.in

Edited By : Poulami Mondal, Digital & Creative Media Executive (Creative Writer)
Email: poulami.mondal@iitkgp.ac.in, media@iitkgp.ac.in, Ph. No.: +91-3222-282007

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Worldwide increase in extreme precipitation: A manifestation of climate change

Since the 1970s, global climate change and consequent warming of atmospheric system have led to a significant increase in extreme precipitation across the world, revealed by the IIT Kharagpur researchers through a global analysis.

“The global climate change and consequent warming of atmospheric system have altered the regular spatio-temporal distribution of precipitation. Our researchers also found that, the extent of increase in precipitation extremes is comparatively less near equator and reaches peak around mid-latitudes.”, mentioned the lead researcher, Prof Rajib Maity, Department of Civil Engineering.

The researchers have considered gridded observational- reanalysis precipitation dataset (1948-2012) and two important extreme precipitation measures from hydrological design and planning point of view, namely Annual Maximum Daily Precipitation (AMDP) & Probable Maximum Precipitation (PMP). The research finding has been published in the Science Reports journal by Nature Publishing Group.

“Globally, the importance of AMDP and PMP is hydrologic planning and design is enormous. It ranges from flood assessment studies to design to high-risk high-cost water-energy infrastructures such as, dams, drainage network, flood management structures and even nuclear power plants.”, added Prof Maity.

“Intensification of precipitation extremes has resulted in substantial increase in Europe, North America and Northern Asia. Furthermore, the researchers have observed a similar increasing pattern in India, especially in the Southern peninsula, in contrast to the Northern Gangetic plain.”, said Prof Virendra Kumar Tewari, the Director of IIT Kharagpur.

AMDP is reported to increase for almost two-third of the global land area. The variability of AMDP is found to increase more than its mean that eventually results in increase PMP almost worldwide. Continent-wise, such increase in AMDP and PMP is true for all continents except some parts of Africa. The zone-wise analysis (dividing the globe into nine zones with uniform precipitation characteristics) reveals that zones of ‘moderate precipitation’ and ‘moderate seasonality’ exhibit the maximum increases in PMP.

“Recent increased in pole-ward heat and moisture transport as a result of Arctic Amplification (AA) may be associated with such mid-latitude intensification of precipitation extremes in the Northern hemisphere”, added Subharthi Sarkar, working under the guidance of Prof Rajib Maity as a Ph.D. Scholar.

Media Contact: Prof Rajib Maity, Associate Professor, Email: rajib@civil.iitkgp.ac.in, Ph:.+91-3222-283442

Contact: Paramita Dey, Junior Assistant

Email: media@iitkgp.ac.in, Ph. No.: +91-3222-282004