2-Dec-2021: Swarnajayanti fellow exploring ways of enhancing ocean alkalinity for removing atmospheric carbon dioxide
Arvind Singh, Associate Professor at the Physical Research Laboratory, Ahmedabad, a Swarnajayanti fellow of 2020-21, is examining the role of enhancing ocean alkalinity for removing atmospheric carbon dioxide to tackle global climate change problems. Increasing emission of carbon dioxide in the atmosphere due to anthropogenic and other processes is a global problem that scientists are trying to tackle through various approaches.
Arvind Singh, a physicist by training and a biogeochemist by profession who won the Swarnajayanti fellowship instituted by the Department of Science and Technology, will identify minerals that can be used to enhance ocean alkalinity in a sustained way, examine the impact of increased ocean alkalinity on carbon, nitrogen and phosphorous cycles, and understand the effect of increased alkalinity on phytoplankton and bacterial community structure.
The scientist highlighted that it is quite clear that over the coming decades, we might need reservoirs that can store up to trillions of tons of CO2 emitted from industrial and other man-made emissions.
“Based on our understanding of the intense chemical weathering resulting in global cooling in the Cenozoic era (66 million years), it has been proposed that the enhanced ocean alkalinity through large scale mineral dissolution has the potential to provide a solution to store large amount of CO2 in the ocean,” the scientist pointed out.
He explains that mineral dissolution will lead to a change in the ocean carbonate chemistry equilibrium towards HCO3− and CO32− (i.e., increase in alkalinity) so that additional CO2 from the atmosphere could be dissolved and stored for a long time (more than 1000 years) in the ocean. It may be possible to sequester up to trillion tons of carbon without surpassing present-day carbonate saturation states in the ocean. In turn, the impacts of elevated alkalinity will be potentially small and may even help to reduce the effects of ocean acidification on microbial ecosystem, but these aspects have not been tested experimentally.
Arvind uses stable isotopes of C (13C) and N (15N) to understand elemental cycling in the ocean. His work blends stable isotopes, in-situ and satellite observations, microbiology, and statistical modelling to make quantitative estimates of carbon and nitrogen fluxes in the ocean. His Ph.D. work provided first direct estimate of N2 fixation rates in the Arabian Sea. He worked on elemental stoichiometry in the North Atlantic and the effect of ocean acidification on N2 fixation rates. He studied niche construction theory, role of eddies on ocean biological pumps, and contribution of atmospheric deposition to new nitrogen. His seminal work emphasized that C: N:P is not fixed in oceanic plankton and nutrients.
Further, changes in nutrient stoichiometry (N:P) might lead to change in marine phytoplankton community. His research underlined that the increase in atmospheric deposition can result in increase in CO2 sequestration but can also enhances N2O in the atmosphere. His palaeoclimate work highlighted that the relationship of oxygen isotopic composition (δ18O) and salinity is variable in ocean. In a novel way, he estimated Himalayan ice melt in the last twenty years using 18O isotopic records in the ocean.
5-Aug-2021: Stress on Himalayan River Systems
Snow and glacier are perennial source of water for rivers originating from the Himalayas. Glaciers receive and accumulate snow in winter and release melt water in summer through surface flow, ground water seepage, etc. Studies have revealed that the Himalayan glaciers are retreating in general but not at a rapid pace. The rate of melting/recession varies from glaciers to glaciers depending on its topography and climatic variability of the region. Studies have shown that glaciers with an area of more than 10 square km are unlikely to get affected appreciably in the coming years. However, smaller glaciers of less than 2 square Km area are likely to show rapid changes.
Water being a State subject, steps for augmentation, conservation and efficient management in order to ensure sustainability of water resources are primarily undertaken by the respective State Governments which include creation of storages, restoration of water bodies, rain water harvesting, artificial recharge to ground water, integrated water shed development, adopting of better irrigation practices, etc. In order to supplement the efforts of the State Governments, Central Government provides technical and financial assistance to them through various schemes and programmes. The National Water Policy-2012 also emphasizes conservation & protection of water and highlights the need for augmenting the availability of water through rain water harvesting, direct use of rainfall and other management measures. National Water Mission (NWM) of Ministry of Jal Shakti has initiated “Jal Shakti Abhiyan: Catch the Rain” campaign in order to promote creation of Rain Water Harvesting Structures (RWHS) suitable to the climatic conditions and sub-soil strata to store rain water. Central Ground Water Board is implementing a nationwide programme of “National Aquifer Mapping and Management (NAQUIM)” for mapping of aquifers (Water bearing formations), their characterization and development of aquifer management plans to facilitate sustainable development of ground water resources. Atal Bhujal Yojana (ABHY), a scheme for sustainable management of ground water with community participation is being taken up in the identified over-exploited and water stressed areas in seven States.
29-Jul-2021: Intensity of severe cyclonic storms increasing in the North Indian Ocean region due to atmospheric parameters related to global warming
The intensity of severe cyclonic storms in the North Indian Ocean region has shown an increasing trend in the past four decades, says a recent study by Indian Scientists. The increasing intensity of severe cyclonic storms with major socioeconomic implications was due to atmospheric parameters like higher relative humidity, especially at mid atmospheric level, weak vertical wind shear as well as warm sea surface temperature (SST). This indicates the role of global warming in bringing about this increasing trend.
The impact of global warming due to climate change and its effect on extreme weather events such as frequency and high-intensity tropical cyclones formed over global ocean basins is a matter of concern. High-intensity cyclones have become more frequent in the North Indian Ocean, causing significant risk and vulnerability to the coastal regions.
A team of scientists including Jiya Albert, Athira Krishnan, and Prasad K. Bhaskaran from the Department of Ocean Engineering & Naval Architecture, IIT Kharagpur, jointly with K. S. Singh, Centre for Disaster Mitigation and Management, VIT University, Vellore, with the support from the Department of Science & Technology, Government of India under the Climate Change Programme (CCP), studied the role and influence of critical atmospheric parameters in large-scale environmental flow and El Niño–Southern Oscillation (ENSO) on tropical cyclone activity in the North Indian Ocean. The research which demonstrated substantial correlation with a measure on the destructive potential of tropical cyclones called Power Dissipation Index was published in the journal ‘Climate Dynamics’, Springer recently. In particular, the tropical cyclones that formed during the pre-monsoon season exhibited an increasing trend. In the recent decade (2000 onwards), the trend was found to be quite substantial in both Bay of Bengal and the Arabian Sea basins.
Findings from the study indicated that strong mid-level relative humidity (RH), positive low-level relative vorticity (RV), weak vertical wind shear (VWS), warm sea surface temperature (SST), and suppressed outgoing longwave radiation (OLR) are responsible for the increased tropical cyclone activity in the North Indian Ocean. It was found that RH, RV, VWS are distinct during pre-monsoon seasons of La Niña, and that favors the genesis of severe cyclone formation over this region. Environmental variables such as SST, wind streamlines, Vertical Velocity, and Specific Humidity exhibited comparable contributions towards cyclogenesis during both El Niño and La Niña phases.
Investigation of the role of additional parameters such as water vapor and zonal Sea Level Pressure gradients revealed the possible linkage of La Niña years on increased severity of tropical cyclones. The study reported an increased amount of water vapor content in the troposphere, and during the past 38 years at 1.93 times as compared to the base year 1979. During the past two decades (2000-2020), the La Niña years experienced almost double the number of intense cyclones compared to the El Niño years. Besides, during La Niña years, the positional shifts in average cyclogenesis of intense cyclones in Bay of Bengal are analogous with the observations for the western North Pacific Ocean basin. An increasing trend in the climatological distribution of water vapor content was also seen during these years, with peaks localized over the Andaman Sea and North China Sea regions in conjunction with the increased frequency of severe cyclones.
The new findings from this study are expected to augment advanced research in tropical cyclone activity for North Indian Ocean region and also provide the scope for a detailed investigation on the possible linkages and teleconnection with other climate indices over the North Indian Ocean.