bala

Prof. G. Bala is a well-known climate and carbon cycle scientist who has made seminal contributions to the understanding of mechanisms involved in climate change caused by different forcing agents.

He uses comprehensive Earth system models to identify robust responses of the global climate, carbon and water cycles. His scientific contributions in elucidating the “fast and slow feedbacks” in the global climate system, solar geoengineering and biophysical impacts of land cover change on climate are globally recognized.

His research has important implications for mitigation strategies such as afforestation and climate intervention strategies such as solar geoengineering.

He has served as Lead author, Contributing Author and Expert reviewer for the IPCC (Intergovernmental Panel on Climate Change) AR5 (2013) and AR6 (2021) WG1 reports. He was the National Coordinator for the Environmental Science and Climate Change Theme of IMPRINT, a flagship programme of the Ministry of Human Resources Development (MHRD), Government of India during 2015-2018.

He has served on the editorial boards of Earth System Dynamics (ESD) and Environmental Research Letters (ERL) Review. He is also member of the prestigious “Earth Commission” which is working on identifying science-based safe and just corridor for a resilient Earth system.

Education

QualificationYearUniversity / Institute
Ph.D.1994McGill University
M.Sc.1988University of Poona

PUBLICATIONS*:

    • 126.Loriani, S., and others, 2023: Tipping points in ocean and atmosphere circulations, Egusphere (Submitted)
    • 125.Harpreet Kaur, G. Bala and Ashwin Seshadri, 2023: Why is climate sensitivity larger for radiative forcing imposed in polar latitudes than forcing imposed in tropical latitudes? Journal of Climate (Submitted)
    • 124.Imran, N., N. Nakicenovic, A.Yaqub, B. Sakschewski, S. Loriani, G. Bala, T. Tharammal; C. Zimm, 2023: Permafrost Thawing and Estimates of Vulnerable Carbon in the Northern High Latitudes based on CMIP6 Models, Climatic Change (Submitted)
    • 123.Richardson and others, 2023: Earth beyond six of nine Planetary boundaries, Science Advances, https://www.science.org/doi/10.1126/sciadv.adh2458
    • 122.Rockstrom and others, 2023: Safe and Just Earth System Boundaries, Nature, https://doi.org/10.1038/s41586-023-06083-8
    • 121.Jayakrishnan, K. U. and G. Bala, 2023: A comparison of the climate and carbon cycle effects of carbon removal by afforestation and an equivalent reduction in fossil fuel emissions, Biogeosciences, 20, 1863–1877, https://doi.org/10.5194/bg-20-1863-2023
    • 120.Tresa Mary Thomas, G. Bala, VV Srinivas, 2023: How do the characteristics of monsoon low pressure systems over India change under a warming climate? A modeling study using the NCAR CESMSimulated changes in the characteristics of monsoon low pressure systems in association with climate change, Climate Dynamics, https://doi.org/10.1007/s00382-023-06837-0
    • 119.Shinto Roose, G. Bala, KS Krishnamohan, Long Cao, Ken Caldeira, 2023: Quantification of Tropical Monsoon Precipitation Changes in terms of Interhemispheric Differences in Stratospheric Sulfate Aerosol Optical Depth, Climate Dynamics,https://link.springer.com/article/10.1007/s00382-023-06799-3
    • 118.Tresa Mary Thomas, G. Bala and V. V. Srinivas, 2023: Opposite changes in monsoon precipitation and low pressure system frequency in response to orographic forcing, Journal of Climate “https://doi.org/10.1175/JCLI-D-22-0476.1”
    • 117.Thejna Tharammal, G. Bala, and Jesse Nusbaumer, 2023: Sources of Water Vapor and their Effects on Water Isotopes in Precipitation in the Indian Monsoon Region: A Model-Based Assessment, Nature Scientific Reports, 13 (1), 708, https://doi.org/10.1038/s41598-023-27905-9
    • 116.Harpreet Kaur, G. Bala and Ashwin Seshadri, 2023: Why is Climate Sensitivity for Solar Forcing Smaller than for an Equivalent CO2 Forcing? Journal of Climate, “https://doi.org/10.1175/JCLI-D-21-0980.1”
    • 115.Santy, S., PP Mujumdar, G. Bala, 2022: Increased risk of eutrophication under warming in a highly industrialized stretch of Ganga River, Frontiers in Water, section Water and Climate, https://doi.org/10.3389/frwa.2022.971623
    • 114.Jayakrishnan, K.U., G. Bala, Long Cao, Ken Caldeira, 2022: Contrasting climate and carbon cycle consequences of fossil-fuel use versus deforestation disturbance, Environmental Research Letters, https://doi.org/10.1088/1748-9326/ac69fd
    • 113.Tresa Mary Thomas, G. Bala, VV Srinivas, 2022: CESM simulation of monsoon low pressure systems over India, International Journal of Climatology, http://doi.org/10.1002/joc.7571
    • 112.Krishnamohan, KS, G. Bala, 2022: Sensitivity of tropical monsoon precipitation to the latitude of stratospheric aerosol injections, Climate Dynamics, https://doi.org/10.1007/s00382-021-06121-z
    • 111.Arias, P.A., N. Bellouin, E. Coppola, R.G. Jones, G. Krinner, J. Marotzke, V. Naik, M.D. Palmer, G.-K. Plattner, J. Rogelj, M. Rojas, J. Sillmann, T. Storelvmo, P.W. Thorne, B. Trewin, K. Achuta Rao, B. Adhikary, R.P. Allan, K. Armour, G. Bala, R. Barimalala, S. Berger, J.G. Canadell, C. Cassou, A. Cherchi, W. Collins, W.D. Collins, S.L. Connors, S. Corti, F. Cruz, F.J. Dentener, C. Dereczynski, A. Di Luca, A. Diongue Niang, F.J. Doblas-Reyes, A. Dosio, H. Douville, F. Engelbrecht, V. Eyring, E. Fischer, P. Forster, B. Fox-Kemper, J.S. Fuglestvedt, J.C. Fyfe, N.P. Gillett, L. Goldfarb, I. Gorodetskaya, J.M. Gutierrez, R. Hamdi, E. Hawkins, H.T. Hewitt, P. Hope, A.S. Islam, C. Jones, D.S. Kaufman, R.E. Kopp, Y. Kosaka, J. Kossin, S. Krakovska, J.-Y. Lee, J. Li,T. Mauritsen,T.K. Maycock, M. Meinshausen, S.-K. Min, P.M.S. Monteiro,T. Ngo-Duc, F. Otto, I. Pinto, A. Pirani, K. Raghavan, R. Ranasinghe, A.C. Ruane, L. Ruiz, J.-B. Sallée, B.H. Samset, S. Sathyendranath, S.I. Seneviratne, A.A. Sörensson, S. Szopa, I. Takayabu, A.-M. Tréguier, B. van den Hurk, R.Vautard, K. von Schuckmann, S. Zaehle, X. Zhang, and K. Zickfeld, 2021: Technical Summary. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY,USA, pp. 33−144. doi:10.1017/9781009157896.002
    • 110.Lee, J.-Y., J. Marotzke, G. Bala, L. Cao, S. Corti, J.P. Dunne, F. Engelbrecht, E. Fischer, J.C. Fyfe, C. Jones, A. Maycock, J. Mutemi, O. Ndiaye, S. Panickal, and T. Zhou, 2021: Future Global Climate: Scenario-Based Projections and Near- Term Information. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy,J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 553–672, doi:10.1017/9781009157896.006
    • 109.Zhao, M., Long Cao, G. Bala, Lei Duan, 2021: Climate response to latitudinal and altitudinal distribution of stratospheric sulfate aerosols, Journal of Geophysical Research-Atmosphere, hhttps://doi.org/10.1029/2021JD035379
    • 108.Krishnamohan, KS, Angshuman Modak, G. Bala, 2021: Effects of local and remote black carbon aerosols on summer monsoon precipitation over India, Environmental Research Communications, https://doi.org/10.1088/2515-7620/ac18d1
    • 107.Johan Rockström…. G. Bala…., 2021: Identifying a safe and just corridor for people and the planet, Earth’s Future, https://doi.org/10.1029/2020EF001866
    • 106.Tresa Mary Thomas, G. Bala and V. V. Srinivas, 2021: Characteristics of the Monsoon Low Pressure Systems in the Indian Subcontinent and the Associated Extreme Precipitation Events, Climate Dynamics, https://doi.org/10.1007/s00382-020-05562-2
    • 105.Mengying Zhao, Long Cao, Lei Duan, G. Bala, K. Caldeira, 2021: Climate more response to marine cloud brightening than ocean albedo modification: A model study, Journal of Geophysical Research – Atmospheres, https://doi.org/10.1029/2020JD033256
    • 104.Thejna Tharammal, G. Bala, André Paul, David Noone, Astrid Contreras-Rosales, Kaustubh Thirumalai, 2020: Evolution of Asian monsoon and stable water isotope ratios during the Holocene: Isotope-enabled climate model simulations and proxy data comparisons, Quaternary Science Reviews, https://doi.org/10.1016/j.quascirev.2020.106743
    • 103.Duan, L., Long Cao, G. Bala and K. Calderia, 2020: A model-based investigation of terrestrial carbon response to four radiation modification approaches, Journal of Geophysical Research-Atmos., https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JD031883
    • 102.Krishnamohan, KS, G. Bala, Long Cao, Lei Duan and Ken Caldiera, 2020: The climatic effects of hygroscopic growth of sulfate aerosols in the stratosphere, Earth’s Future, https://doi.org/10.1029/2019EF001326
    • 101.Santy, S., PP Mujumdar, G. Bala, 2020: Pollution of River Ganga in an Industrialized Region: Effects of Agriculture, Industrial Effluents and Changing Climate, Nature Scientific Reports, https://doi.org/10.1038/s41598-020-66171-x
    • 100.Krishnamohan, KS, G. Bala, Long Cao, Lei Duan and Ken Caldiera, 2019: Climate System Response to Stratospheric Sulfate Aerosols: Sensitivity to Altitude of Aerosol Layer, Earth System Dynamics, https://doi.org/10.5194/esd-10-885-2019
    • 99.Thejna Tharammal, G. Bala, Devaraju Narayanappa, and Rama Nemani, 2019: A review of the major drivers of the terrestrial carbon uptake: Model-based assessments, consensus and uncertainties, Environmental Research Letters Review, https://doi.org/10.1088/1748-9326/ab3012
    • 98.Duan, L., Long Cao, G. Bala and K. Calderia, 2019: Climate Response to Pulse versus Sustained Stratospheric Aerosol Forcing, Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL083701
    • 97.Modak, A., and G. Bala, 2019: Efficacy of black carbon aerosols: the role of shortwave cloud feedback, Environmental Research Letters, https://iopscience.iop.org/article/10.1088/1748-9326/ab21e7
    • 96.Sayli, T.A., A.V.Kulkarni and G. Bala, 2019: An assessment of Climate change impacts on glacier mass balance and geometry in the Chandra Basin, Western Himalaya for the 21st century, Environmental Research Communications, https://doi.org/10.1088/2515-7620/ab1d6d
    • 95.H. Hashimoto, R. Nemani, G. Bala, L. Cao and others, 2019: Constraints to vegetation growth reduced by region-specific changes in seasonal climate, Climate, 7, 27; doi:10.3390/cli7020027
    • 94.Chi Chen, and others, 2019: China and India lead in greening the world through land-use management, Nature Sustainability, 2, 122–129.
    • 93.Ananya Rao, G. Bala, N.H.Ravindranath, R. Nemani, 2019: Multi-Model Assessment of Trends, Variability and Drivers of Terrestrial Carbon Uptake in India, Journal of Earth System Sciences, https://doi.org/10.1007/s12040-019-1120-y, 128:99
    • 92.Bala, G., and Akhilesh Gupta, 2019: Geoengineering Research in India, Bull. Amer. Met. Soc., doi: 10.1175/BAMS-D-18-0122.1
    • 91.Weile Wang, Ramakrishna Nemani, Hirofumi Hashimoto1, Sangram Ganguly, Dong Huang, Yuri Knyazikhin, Ranga Myneni, and G. Bala, 2018: An Interplay between Photons, Canopy Structure, and Probability: An Review of the Spectral Invariants Theory of 3D Canopy Radiative Transfer Processes, Remote Sens. 2018, 10, 1805; doi:10.3390/rs10111805
    • 90.Lei Duan, Long Cao, G. Bala and K. Caldeira, 2018: Comparison of the Fast and Slow Climate Response to Three Radiation Management Geoengineering Schemes, J. Geophys. Res. -Atmos., 10.1029/2018JD029034
    • 89.Thejna, T., G. Bala, N.Devaraju and R. Nemani, 2018: Potential roles of CO2 fertilization, climate warming, nitrogen deposition and land use and land cover change on the global terrestrial carbon uptake in the 21st century, Climate Dynamics, https://doi.org/10.1007/s00382-018-4388-8
    • 88.Chaitra, A., and others, 2018: Impact of Climate Change on Vegetation Distribution and Net Primary Productivity of Forests of Himalayan River Basins: Brahmaputra, Koshi and Indus, American Journal of Climate Change, 7, 271-294.
    • 87.Devaraju, N., Nathalie de Noblet-Ducoudré, Benjamin Quesada & G. Bala, 2018: How important are indirect biophysical effects of land use and land cover changes compared to direct effects? Journal of Climate, doi: 10.1175/JCLI-D-17-0563.1
    • 86.Muthyala, R., G. Bala, and A. Nalam, 2018: Regional scale analysis of climate extremes in an SRM geoengineering simulation, Part 1: Precipitation Extremes, Current Science, 114 (5), 1024-1035
    • 85.Muthyala, R., G. Bala, A. Nalam, 2018: Regional scale analysis of climate extremes in an SRM geoengineering simulation, Part 2: Temperature Extremes, Current Science, 114 (5), 1036-1045
    • 84.Modak, A., G. Bala, K. Caldeira, and L. Cao, 2018: Does shortwave absorption by Methane influence its effectiveness? Climate Dynamics, https://doi.org/10.1007/s00382-018-4102-x
    • 83.L. Cao, Lei Duan, G. Bala, K. Caldeira, 2017: Simultaneous stabilization of temperature and precipitation through cocktail geoengineering, Geophysical Research Letters, 10.1002/2017GL074281
    • 82.Sharma, J., S. Upgupta, M. Jayaraman, R.K.Chaturvedi, G. Bala and N.H. Ravindranath, 2017: Inherent and climate change vulnerability of forests and plantations in India, Environmental Management, DOI 10.1007/s00267-017-0894-4
    • 81.Tawde, S. A., A. V. Kulkarni and G. Bala, 2017: An estimate of glacier mass balance for Chandra basin, western Himalaya for the period 1989-2009, Annuals of Glacialogy, doi: 10.1017/aog.2017.18
    • 80.Nalam, A., G. Bala and A. Modak, 2017: Effects of Arctic Geoengineering on Tropical Precipitation, Climate Dynamics, DOI 10.1007/s00382-017-3810-y
    • 79.K. Caldeira and G. Bala, 2017: Reflecting on 50 years of geoengineering research, Earth’s Future, DOI: 10.1002/2016EF000454
    • 78.Thejna, T., G. Bala, D. Noone, 2017: Impact of deep convection on the isotopic amount effect in tropical precipitation, Journal of Geophysical Research-Atmospheres, DOI: 10.1002/2016JD025555
    • 77.A. Modak, G. Bala, L. Cao, and K. Caldeira, 2016: Why must a solar forcing be larger than a CO2 forcing to cause the same global mean surface temperature change? Environmental Research Letters, doi:10.1088/1748-9326/11/4/044013
    • 76.Sayli A Tawde, A. V. Kulkarni and G. Bala, 2016: Estimation of glacier Mass balance: An approach based on satellite-derived snowlines and temperature index model, Current Science, 111(12), 1977-1989
    • 75.L. Cao, Lei Duan, G. Bala and K. Caldeira, 2016: Simulated long-term climate response to idealized solar geoengineering, Geophys. Res. Lett., DOI: 10.1002/2016GL068079
    • 74.Tashina Esteves, Darshini Ravindranath, Satyasiba Beddamatta, K V Raju, Jagmohan Sharma, G Bala and Indu K Murthy, 2016: Multi-scale vulnerability assessment for adaptation planning: A case study for Karnataka, Current Science, 110(7), 1225-1239.
    • 73.N. Devaraju, G. Bala, K. Caldeira and R. Nemani, 2015: A model based investigation of the relative importance of CO2-fertilization, climate warming, nitrogen deposition and land use change on the global terrestrial carbon uptake in the historical period, Climate Dynamics, DOI 10.1007/s00382-015-2830-8.
    • 72.L. Cao, G. Bala, Meidi Zheng and K. Caldeira, 2015: Fast and slow climate responses to CO2 and solar forcing: A linear multivariate regression model characterizing transient climate change, Journal of Geophysical Research, DOI: 10.1002/2015JD023901
    • 71.N. Devaraju, G. Bala and A. Modak, 2015: Effects of large scale deforestation on precipitation in the monsoon regions: Remote versus local effects, Proceedings of the National Academy of Sciences, doi.10.1073/pnas.1423439112
    • 70.Sharma, J., Sujata Upgupta, Rajesh Kumar, R. Chaturvedi, G. Bala, N.H. Ravindranath, 2015: Assessment of ‘inherent vulnerability’ of forests for building resilience to climate change in Western Ghats Karnataka, India, Mitigation and Adaptation Strategies for Global Change, DOI 10.1007/s11027-015-9659-7
    • 69.N. Devaraju, G. Bala, and R. Nemani, 2015: Modeling the influence of land-use changes on biophysical and biochemical interactions at regional and global scales, Plant, Cell and Environment, doi: 10.1111/pce.12488
    • 68.S. Kalidindi, G. Bala, A. Modak and K. Caldeira, 2014: Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols, Clim. Dyn., DOI 10.1007/s00382-014-2240-3
    • 67.Angshuman Modak, and G. Bala, 2014: Sensitivity of simulated climate to latitudinal distribution of solar insolation reduction in solar radiation management, Atmos. Chem. Phys., 14, 7769–7779. [Also in Atmos. Chem. and Phy. Discuss, 13, 25387-25415, doi:10.5194/acpd-13-25387-2013]
    • 66.Chaturvedi, R., A. Kulkarni, Y. Karyakarte, J. Joshi, G. Bala, 2014: Glacial Mass balance changes in Karakoram and Himalaya based on CMIP5 climate change projections, Climatic Change, DOI 10.1007/s10584-013-1052-5
    • 65.Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell, A. Chhabra, R. DeFries, J. Galloway, M. Heimann, C. Jones, C. Le Quéré, R.B. Myneni, S. Piao and P. Thornton, 2013: Carbon and Other Biogeochemical Cycles. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
    • 64.Sharma, J., R. Chaturvedi, G. Bala, N. H. Ravindranath, 2013: Assessing “inherent vulnerability” of forests: a methodological approach and a case study from Western Ghats, India, Mitigation and adaptation strategies under global change, DOI 10.1007/s11027-013-9508-5
    • 63.Sharma, J., R. Chaturvedi, G. Bala, N. H. Ravindranath, 2013: Challenges in vulnerability assessment of forest carbon management under climate change, Carbon Management, Vol. 4, No. 4, Pages 403-411 , DOI 10.4155/cmt.13.35
    • 62.G. Bala, N. Devaraju, R. K. Chaturvedi, K. Caldeira, R. Nemani, 2013: Nitrogen Deposition: How important is it for global terrestrial carbon uptake? Biogeosciences, 10, 7147–7160, doi:10.5194/bg-10-7147-2013 (Also published in Biogeosciences Discussion, 10, 11077-11109, doi:10.5194/bgd-10-11077-2013)
    • 61.K. Caldeira, G. Bala, L.Cao, 2013: The Science of Geoengineering, Annual Reviews in Earth and Planetary Sciences, 41:231–56, 10.1146/annurev-earth-042711-105548
    • 60.G. Bala, Jaideep Joshi, R. Chaturvedi, H.V. Gangamani, Hirofumi Hashimoto R. Nemani, 2013: Trends and Variability in AVHRR-derived NPP in India, Remote Sens. 2013, 5, 810-829; doi:10.3390/rs5020810
    • 59.Chaturvedi, R., Jaideep Joshi, J. Mathangi, G. Bala, N.H.Ravindranath, 2012:Multi-model projection of climate change for India under representative concentration pathways. Current Science, 103(7), 1-12.
    • 58.G. Bala, Sujith Krishna, Devaraju Narayanappa, Long Cao, K. Caldeira, R. Nemani, 2012: An estimate of equilibrium sensitivity of terrestrial carbon cycle using NCAR CCSM4, Climate Dynamics, DOI 10.1007/s00382-012-1495-9
    • 57.Cao, L., G.Bala, K. Caldeira, 2012: Climate response on the time scale of days to changes in atmospheric carbon dioxide, Env. Res. Letters, doi:10.1088/1748-9326/7/3/034015
    • 56.G. Bala, and B. Nag, 2011: Albedo enhancement over land to counteract global warming: Impacts on hydrological cycle, Climate Dynamics, DOI 10.1007/s00382-011-1256-1
    • 55.N.H. Ravindranath, Sandhya Rao, Nitasha Sharma, Malini Nair, R Gopalakrishnan, Ananya S. Rao, S. Malaviya, Rakesh Tiwari, Anitha Sagadevan, M. Munsi and G. Bala, 2011: Climate Change Vulnerability Profiles for Northeast India, Current Science, 101(3), 384-394.
    • 54.R. Gopalakrishnan, Mathangi Jayaraman, G. Bala and N.H. Ravindranath, 2011: Impact of Climate Change on Indian Forests, Current Science, 101(3), 348-355.
    • 53.N. Devaraju, L. Cao, G. Bala, K. Caldeira, and R. Nemani, 2011: A model investigation of vegetation-atmosphere interactions on a millennial time scale, Biogeosciences, doi:10.5194/bg-8-3677-2011, 8, 3677–3686, 2011 (Also, N. Devaraju, L. Cao, G. Bala, K. Caldeira, and R. Nemani, 2011: A model investigation of vegetation-atmosphere interactions on a millennial time scale, Biogeosciences Discussion, doi:10.5194/bgd-8-8761-2011)
    • 52.G. Ban-Weiss, G. Bala, L. Cao, J. Pongratz and K. Caldeira, 2011: Climate forcing and response to idealized changes in surface latent and sensible heat fluxes, Environmental Research Letters, doi:10.1088/1748-9326/6/3/034032
    • 51.R. Gopalakrishnan, G. Bala, M. Jayaraman, L. Cao, R. Nemani, N.H.Ravindranath, 2011: Sensitivity of terrestrial water and energy budgets to CO2-physiological forcing: an investigation using an offline land model, Environmental Research Letters, doi:10.1088/1748-9326/6/4/044013
    • 50.G. Ban-Weiss, L. Cao, G. Bala, K. Caldeira, 2011: Dependence of surface climate response on the altitude of black carbon aerosols, Climate Dynamics, DOI 10.1007/s00382-011-1052-y
    • 49.L. Cao, G. Bala, K. Caldeira, 2011: Why is there a short-term increase in global precipitation in response to diminished CO2 forcing? Geophys. Res. Lett., 38, L06703, doi:10.1029/2011GL046713
    • 48.G. Bala, R. Gopalakrishnan, M. Jayaraman, R. Nemani, N. H. Ravindranath, 2010: CO2-fertilization and the potential terrestrial carbon uptake in India, Mitigation and Adaptation Strategies for Global Change, DOI 10.1007/s11027-010-9260-z
    • 47.R. Chaturvedi, R. Gopalakrishnan, M. Jayaraman, K. Krishna, Savitha Patwardhan, G. Bala, N.V.Joshi, R. Sukumar, N.H.Ravindranath, 2010: Impact of climate change on Indian Forests: A dynamic modeling approach, Mitigation and Adaptation Strategies for Global Change, DOI 10.1007/s11027-010-9257-7
    • 46.R. Gopalakrishnan, M. Jayaraman, R. Chaturvedi, G. Bala, N.H.Ravindranath, 2010: Effect of climate change on teak in India: A modeling based approach, Mitigation and Adaptation Strategies for Global Change, DOI 10.1007/s11027-010-9258-6
    • 45.G. Bala, K. Caldeira, R. Nemani, L. Cao, G. Ban-Weiss, and H. Shin, 2010: Albedo-enhancement of marine clouds to counteract global warming: Impacts on hydrology, Climate Dynamics, DOI 10.1007/s00382-010-0868-1
    • 44.M. Wehner, G. Bala, P. B. Duffy, B. Santer, A. Mirin, Raquel Romano, Joseph Sirutis, and Michael Fiorino, 2010: Towards direct simulation of future tropical cyclone statistics in a high resolution global atmospheric model, Advances in Meteorology, doi:10.1155/2010/915303
    • 43.L. Cao, G. Bala, K. Caldeira, R. Nemani, George Ban-Weiss, 2010: Importance of carbon dioxide physiological forcing to future climate change, Proceedings of the National Academy of Sciences, 107 (21) 9513-9518.
    • 42.L. Cao, G. Bala, K. Caldeira, R. Nemani, George Ban-Weiss, 2009: Climate response to physiological forcing of carbon dioxide simulated by the coupled Community Atmosphere Model (CAM3.1) and Community Land Model (CLM3.0), Geophysical Research Letters, vol. 36, L10402, doi:10.1029/2009GL037724.
    • 41.G. Bala, K. Calderia, R. Nemani, 2009: Fast versus slow response in climate change: Implication to the global hydrological cycle, Climate Dynamics, DOI 10.1007/s00382-009-0583-y
    • 40.G. Bala, 2009: Problems with geoengineering schemes to combat climate change, Current Science, 96(1), 41-48.
    • 39.Das, T., H. G. Hidalgo, M. D. Dettinger, D. R. Cayan, D. W. Pierce, C. Bonfils, T. P. Barnett, G. Bala, A. Mirin: Structure and origins of trends in hydrological measures over the western United States, 2009: Journal of Hydrometeorology, 10, 871-892.
    • 38.M. Wehner, R. Smith, G. Bala, and P. Duffy, 2009: The effect of horizontal resolution on simulation of very extreme US precipitation events in a global atmosphere model, Climate dynamics, DOI 10.1007/s00382-009-0656-y
    • 37.P. Caldwell, S. Chin, D. Bader, and G. Bala, 2009: Evaluation of a WRF dynamical downscaling over California, Climatic Change, 95, 499-521.
    • 36.D. Lobell, G. Bala, A. Mirin, T. J. Phillips, R. Maxwell, D. Rotman, 2009: Regional differences in influence of irrigation on climate, J. Climate, 22, 2248-2255.
    • 35.Hidalgo H.G., Das T., Dettinger M.D., Cayan D.R., Pierce D.W., Barnett T.P., Bala G., Mirin A., Wood, A.W., Bonfils C., Santer B.D., Nozawa T, 2008: Detection and attribution of climate change in streamflow timing of the western United States, J. Climate,22, 3838-3855.
    • 34.G. Bala, R. Rood, D. Bader, A.Mirin, D. Ivanova, C. Drui, 2008: Simulated Climate near Steep Topography: Sensitivity to Dynamical Methods for Atmospheric Transport, Geophys. Res. Lett., 35, L14807, doi: 10.1029/2008GL033204
    • 33.G. Bala, P. B. Duffy, and K. E. Taylor, 2008: Impact of geoengineering schemes on the global hydrological cycle, Proceeding of the National Academy of Sciences, 105(22), 7664-7669, https://doi.org/10.1007/s00382-018-4102-x
    • 32.Tim P. Barnett, David W. Pierce, Hugo G. Hidalgo, Celine Bonfils, Benjamin D. Santer, Tapash Das, G. Bala, Andrew W. Wood, Toru Nozawa, Arthur A. Mirin, Daniel R. Cayan, Michael D. Dettinger, 2008: Human-induced changes in the hydrology of the western United States, Science, 319, 1080-1083.
    • 31.Céline Bonfils, Benjamin D. Santer, David W. Pierce, Hugo G. Hidalgo, G. Bala, Tapash Das, Tim P. Barnet, Michael Dettinger, Daniel R. Cayan , Charles Doutriaux, Andrew W. Wood, Art Mirin, Toru Nozawa, 2008: Detection and attribution of temperature changes in the mountainous western United States, J. Climate, v. 21, p. 6404-6424.
    • 30.David W. Pierce, Tim P. Barnett, Hugo G. Hidalgo, Tapash Das, Celine Bonfils, Benjamin D. Santer, G. Bala, Michael D. Dettinger, Daniel R. Cayan, Art Mirin, Andrew W. Wood, Toru Nozawa, 2008: Attribution of declining western U.S. snowpack to human effects, J. Climate, v. 21, p. 6425-6444.
    • 29.Bala, G., R. Rood, A. Mirin, J. McClean, K. Achuta Rao, D. Bader, P. Gleckler, R. Neale, P. Rash, 2008: Evaluation of a high-resolution CCSM3 simulation with a Finite Volume dynamical core for the atmosphere J. Climate, 21(7), 1467-1486.
    • 28.Kim, S.-J. T. J. Crowley, D. Erickson, G. Bala, P. B. Duffy, B. Y. Lee, High-resolution simulation of the last glacial maximum, 2008: Climate Dynamics, 31, 1-16.
    • 27.Bala, G., K. Caldeira, M. Wickett, T. J. Phillips, D. Lobell, C. Delire, and A. Mirin, 2007: Combined climate and carbon cycle effects of global deforestation, Proceedings of the National Academy of Sciences, 104(16), 6550-6555.
    • 26. Lobell, D., G. Bala, C. Bonfils, P. B. Duffy, 2006: Potential bias of model projected greenhouse warming in irrigated regions, Geophys. Res. Lett., 33, L13709.
    • 25.Lobell, D., G. Bala, P. Duffy, 2006: Biogeophysical impacts of cropland management changes on climate, Geophys. Res. Lett., 33, L06708.
    • 24.Bala, G., K. Caldeira, A. Mirin, M. Wickett, C. Delire, 2005: Biophysical effects of CO2-fertilization on global climate, Tellus B, doi:10.1111/j.1600-0889.2006.00210.x
    • 23.Gibbard, S., K. Caldeira, G. Bala, T. Phillips, and M. Wickett, 2005: The effects of land cover changes on global climate, Geophys. Res. Lett., 32, doi:10.1029/2005GL024550.
    • 22.Gettelman, A., B. Collins, E. J. Fetzer, A. Eldering, F. W. Irion, P. Duffy, G. Bala, 2006: A satellite climatology of upper tropospheric relative humidity and implications for climate, J. Climate, 19(23), 6104-6121.
    • 21.Friedlingstein, P., P. Cox, R. Betts, V. Brovkin, I. Fung, G. Bala, C. Jones, M. Kawamiya, K. Lindsay, D. Mathews, T. Raddatz, P. Rayner, E. Roeckner, S. Thompson, and N. Zeng, 2005: Climate-carbon feedback analysis: Results from the C4MIP model intercomparison, J. Climate, 13, 3337-3353.
    • 20.Oliker, L., J. Carter, M. Wehner, A. Canning, S. Ethier, B. Govindasamy, A. Mirin, D. Parks, 2005: Leading computational methods on scalar and vector HEC platforms, SC 2005: High performance computing, networking, and storage conference, Seatle, Washington, Nov. 12-18, 2005.
    • 19.Bala, G., K. Caldeira, A. Mirin, M. Wickett, and C. Delire, Multi-century changes to global climate and carbon cycle model: Results from a Coupled Climate and Carbon Cycle Model 2005: J. Climate, 18, 4531-4544.
    • 18.Govindasamy, B., S. Thompson, A. Mirin, M. Wickett, K. Caldeira , and C. Delire, 2005: Increase of Carbon Cycle Feedback with Climate Sensitivity: Results from a Coupled Climate and Carbon Cycle Model, Tellus, 57(B), 153-163.
    • 17.Thompson, S. L., B. Govindasamy, A. Mirin, K. Caldeira, C. Delire, J. Milovich, M. Wickett, D. Erickson, 2004: Quantifying the Effects of CO2-fertilizated vegetation on future global climate and carbon dynamics, Geophys. Res. Lett., 31, L23211.
    • 16.Iorio, J., P. Duffy, B. Govindasamy, and S. L. Thompson, Effects of increased resolution on the simulation of daily precipitation statistics in the US , 2004: Climate Dynamics, 23, 243-258.
    • 15.Duffy, P. B., B. Govindasamy, J. P. Iorio, J. Milovich, K. R. Sperber, K. E. Taylor, M. F. Wehner, and S. L. Thompson, 2003: High resolution simulations of global glimate, Part 1: Present Climate, Climate Dynamics, 21, 371-390.
    • 14.Govindasamy, B., P. B. Duffy, J. Coquard, 2003: High resolution simulations of global, Part 2: Effects of increased greenhouse gases, Climate Dynamics, 21, 391-404.
    • 13.Govindasamy, B., K. Caldeira, and P. B.Duffy, 2003: Geoengineering Earth’s radiation balance to mitigate climate change from a quadrupling of CO2, Global and Planetary Change, 37, 157-168.
    • 12.Snyder, M. A., J. L. Bell, L. C. Sloan, P. B. Duffy and B. Govindasamy, 2002: Climate responses to a doubling of atmospheric carbon dioxide for a climatically vulnerable region, Geophys. Res. Lett., 29 (11), 10.1029/2001GL014431.
    • 11.Govindasamy, B., S. Thompson, P. B. Duffy, and K. Caldeira, 2002: Impact of geoengineering schemes on the terrestrial biosphere, Geophys. Res. Lett., 29 (22), 10.1029/2002GL015911.
    • 10.Govindasamy, B., K. E. Taylor, P. B. Duffy, B. J. Santer, A. S. Grossman, and K. E. Grant, 2001: Limitations of the equivalent CO2 approximation in climate change simulations, J. Geophys. Res.. 106, 22-593-22603.
    • 9.B. Govindasamy, Phil Duffy, and Ken Caldeira, 2001: Land use change and Northern Hemisphere cooling, Geophys. Res. Lett., 28 , No. 2, p. 291.
    • 8.B. Govindasamy and Ken Caldeira, 2000: Geoengineering earth’s radiation balance to mitigate CO2-induced climate change, Geophys. Res. Lett., 27, No. 14, p. 2141, https://doi.org/10.1029/1999GL006086
    • 7.B.Govindasamy, M.F.Wehner, C.R.Mechoso, and P.B.Duffy, 1999: The influence of a Soil-Vegetation-Atmosphere Transfer scheme on the simulated climate of LLNL/UCLA AGCM. Global and Planetary Change, 20, 67-86.
    • 6.B.Govindasamy, and S.T.Garner, 1997: The equilibration of short baroclinic waves. J. Atmos Sci., 54, 2850-2871.
    • 5.G.Balasubramanian, and S.T.Garner, 1997: The role of eddy momentum fluxes in shaping the lifecycle of a Baroclinic wave. J. Atmos. Sci., 54, 510-533.
    • 4.G.Balasubramanian, and M.K.Yau, 1996: The lifecycle of a simulated marine cyclone: Energetics and PV Diagnostics. J. Atmos. Sci., 53, 639-563.
    • 3.G.Balasubramanian, and M.K.Yau, 1995: Explosive marine cyclogenesis in a three layer model with a representation of slantwise convection: A sensitivity study. J. Atmos. Sci., 52, 533-550.
    • 2.G.Balasubramanian, and M.K.Yau, 1994a: Baroclinic instability in a two-layer model with parameterized slantwise convection. J. Atmos. Sci., 51, 674-701.
    • 1.G.Balasubramanian, and M.K.Yau, 1994b: Effects of convection on a simulated marine cyclone. J. Atmos. Sci., 51, 2397-2417.

* Please note that the author has used his other names B. Govindasamy and G. Balasubramanian in older publications.

 

BOOK CHAPTER, REPORTS, EDITORIALS, COMMENTARIES:

    • 26.G. Bala, K. Caldeira, and others: United Nations Environment Programme (2023). One Atmosphere: An independent expert review on Solar Radiation Modification research and deployment. Kenya, Nairobi https://www.unep.org/resources/report/Solar-Radiation-Modification-research-deployment
    • 25.Felgenhauer, T., Bala, G., Borsuk, M., Brune, M., Camilloni, I., Wiener, J.B., Xu, J. (2022). Solar Radiation Modification: A Risk-Risk Analysis, Carnegie Climate Governance Initiative (C2G), March, New York, NY: www.c2g2.net
    • 24.G. Bala, Krishnamohan KS and Akhilesh Gupta, 2019: Solar Geoengineering Research activities in India, The Journal of Governance, Volume 18, Special edition on Environment, 264-272
    • 23.G. Bala and Akhilesh Gupta, 2018: ‘India forges ahead with solar-geoengineering studies’, Correspondence, doi: 10.1038/d41586-018-05288-6, Nature, 557, 637, 30 May 2018
    • 22.G. Bala, 2018: Is ocean acidification from rising CO2 a grave threat? Guest Editorial, 114(1), 7-8, 10 January 2018.
    • 21.G. Bala and Thejna Tharammal, 2017: The threat of extreme heat waves and human “survivability” in South Asia, Research News, Current Science, 113(6), 1025.
    • 20.Jagmohan Sharma, Indu K Murthy, T Esteves, Payal Negi, Sushma S, G. Bala and NH Ravndranath: 2017: Vulnerability and Risk Assessment in the Indian Himalayan Region, Framework, Method and Guidelines, Submitted to the Swiss Agency for Development and Cooperation (SDC)
    • 19.G. Bala and A. Gupta, 2017: Geoengineering and India, Meeting Report, Current Science, 113(3), 376-377
    • 18.G. Bala, 2017: Why is a solution to climate Change, environmental degradation and the sustainability crisis eluding us? Guest Editorial, Current Science, 112(7), 1307-1308.
    • 17.NH Ravindranath, G. Bala, S. Upgupta, J. Mathangi, DS Anita, K Sindhu, V Kumar, J. Sharma, A Chaitra, RK Chaturvedi, IK Murthy, LD Bhatia, NK Agarwal, MSR Murhy and FM Qamer, Jan 2017: Projected impacts of climate change on forests in the Brahmaputra, Koshi and upper Indus river Basins, ICIMOD Research Report 2017/1
    • 16.G. Bala, 2016: Are volcanic eruptions causing the current global warming? Guest Editorial, Current Science, 110(3), 283-284.
    • 15.G. Bala and J Srinivasan, 2015: National Climate Science Conference, Meeting Report, Current Science, 109(5), 847-848.
    • 14.G. Bala, 2014: Should we choose geoengineering to reverse global warming? Guest Editorial, Current Science, 25 December 2014.
    • 13.G. Bala, 2014: Can Planting new trees help to reduce global warming, Guest Editorial, Current Science, 25 June 2014.
    • 12.G. Bala, 2013: Why the “hiatus” in global mean surface temperature in the last decade? Guest Editorial, Current Science, 25 October 2013.
    • 11.G. Bala, 2013: Digesting 400 ppm for global mean CO2 concentration, Research News, Current Science, 104(11), 1471-1472.
    • 10.G. Bala, 2013: Space sunshades and climate change, Hand Book on Global Environmental Change
    • 9.N. H. Ravindranath, G. Bala, Anita Sagadevan, Rajiv Chaturvedi and Indu Murthy, 2013: Historical climate trends and climate change projections for Karnataka, Supported by Global Green Growth Institute, Seoul, S Korea.
    • 8.G. Bala, 2011: Counteracting climate change via solar radiation management, Commentary, Current Science, 101(11), 1418-1421.
    • 7.G. Bala, A. Sagadevan, R. Gopalakrishnan and M. Jayaraman, Chapter “Climate Variability and Climate Change Projections-Karnataka region” in the report “Karnataka Climate Change Action Plan” submitted to the government of Karnataka, May 2011.
    • 6.N. H. Ravindranath and G. Bala, 2011 “Forest sector and the global carbon cycle: Analysis of FAO Forest Resource Assessment and IPCC Assessments”, Submitted to Food and Agricultural Organization (FAO), Itay, Rome, 2011.
    • 5.N.H. Ravindranath, G. Bala, Savithri B., Vani S S, Sridhar Patgar, Beerappa M, Indu K Murthy, P R Bhat, Ranjith Gopalakrishnan, Mathangi Jayaraman, Madhushree Munsi, 2011: “Case study of the impacts of climate change on production and flow of forest products and its implications for the livelihoods in the Western Ghats”- NATCOM II report – submitted to the Ministry of Environment and forests.
    • 4.N.H.Ravindranath, G. Bala and others, 2010: “Climate change Vulnerability assessment for NE India” submitted to KFW, Germany.
    • 3.“Natural Ecosystems and Biodiversity” chapter in “Climate Change and India: A 4×4 Assessment,. A sectoral and regional analysis for 2030s” released by MOEF on 16 November 2010 at New Delhi.
    • 2.T.J. Phillips, G. Bala, P. Gleckler, D. Lobell, A. Mirin, R. Maxwell. D. Rotman, 2008: Atmospheric climate model experiments performed at multiple resolutions, LDRD project report, LLNL-TR-400220, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
    • 1.G. Bala, and K. Caldeira, 2006: Mitigation of Anthropogenic climate change via a macro-engineering scheme: Climate modeling results in Macro-Engineering: A Challenge for the Future, edited by V. Badescu, R. B. Cathcart and R.D.Schuiling, Springer publications, 316pp.

RESEARCH:

Earth system modeling, global climate change, solar geoengineering, radiative forcing and feedbacks, global carbon and biogeochemical cycles, climatic effects of land cover and land use change, impacts of climate change on forestry and water resources, global water cycle and regional monsoon systems.

Some recent research from Prof. Bala’s group is discussed below.

1. Climate System Feedbacks

An understanding of the climate response to different radiative forcing agents is fundamental for climate change studies. At the Indian Institute of Science, Bengaluru, India, we use comprehensive coupled climate models to understand the climate response, especially the feedbacks and efficacies, to various forcing agents (e.g., carbon dioxide, solar irradiance, methane, black carbon and sulphate aerosols). Efficacy refers to the effectiveness of a forcing agent, relative to CO2, in changing the global mean surface temperature per unit top of the atmosphere radiative forcing. Our goal is to provide a mechanistic explanation for the dependence of feedback and efficacy on the forcing agents. We use the radiative kernel technique and primarily focus on the Planck, water vapor, albedo, lapse rate and cloud feedbacks which determine the climate response on multi-decadal timescales (Figure 1). Besides feedbacks and efficacies, we also estimate other related metrics such as the radiative forcing, hydrological sensitivity and climate sensitivity. Our calculations are mainly based on climate model simulations performed using the NCAR CESM framework on the supercomputers at the Indian Institute of Science.

In a recent study (2023), we found that solar forcing is less effective than CO2 forcing for the same imposed radiative forcing: the net feedback estimated for CO2 and solar radiative forcing from our model simulations is -1.23 W m-2 K-1 and -1.45 W m-2 K-1, respectively. Our analysis based on the radiative kernel technique showed that the difference in feedback between the two cases is primarily due to differences in lapse rate, water vapor, and cloud feedbacks, The differences in feedbacks arise mainly from differences in the latitudinal structure of forcing and the consequent warming.

Publication:

Harpreet Kaur, G. Bala and Ashwin Seshadri, 2023: Why is Climate Sensitivity for Solar Forcing Smaller than for an Equivalent CO2 Forcing? Journal of Climate, DOI: 10.1175/JCLI-D-21-0980.1

Figure 1 (A comparison of water vapor feedback for CO2 and Solar forcing) The zonal water vapor feedback (W m-2 K-1/100 hPa) for a) CO2 radiative forcing (2XCO2), b) solar radiative forcing (Solar) and c) the difference between the two (Solar minus 2XCO2) calculated using the radiative kernel technique. It can be clearly seen from panel c) that the water vapor is stronger in the tropical upper atmosphere but weaker in the polar regions for solar radiative forcing compared to CO2 radiative forcing

2. Solar geoengineering
Solar geoengineering refers to recent proposals of intentional planetary scale intervention options that would increase the amount of solar radiation reflected by our planet to ameliorate the detrimental impacts of climate change. Deliberate injection of sulphate aerosols into the stratosphere is one of the several solar geoengineering approaches. In this approach, the aerosols injected into the stratosphere such as sulphates would reflect more incoming solar radiation. The consequent reduction in solar radiation at earth’s surface leads to cooling which would and partially or fully offset global warming. At the Indian Institute of Science, Bengaluru, India, we study the impacts of different design strategies of injecting sulphate aerosols into the stratosphere on the Indian Monsoon rainfall.
In a recent research work (2022), we studied the impact of varying the latitudinal position of aerosol injection on the global monsoon precipitation in a climate change scenario (RCP8.5) by analyzing single point injection simulations where 12 tera gram (Tg) of sulfur dioxide (SO2) are injected each year into the stratosphere at latitudes 30°S, 15°S, equator, 15°N, and 30°N. During the period 2043-2049, relative to the climate change scenario, the hemispheric mean summer monsoon precipitation decreases in the hemisphere where aerosols are injected but increases in the opposite hemisphere. The changes in precipitation are linked to the changes in interhemispheric temperature difference and shifts in the intertropical convergence zone. The summer monsoon precipitation over India decreases by about 21% for 15°N and 29% for 30°N injections (Figure 2). Our study highlighted the likelihood of poorly designed climate interventions leading to large regional disruptions while attempting to keep the global mean climate change within a safe limit.

Publication:
Krishnamohan, KS, G. Bala, 2022: Sensitivity of tropical monsoon precipitation to the latitude of stratospheric aerosol injections, Climate Dynamics, https://doi.org/10.1007/s00382-021-06121-z
Figure 2 (Sensitivity of Indian monsoon rainfall to the latitude of stratospheric aerosol injection) The spatial pattern of June to September (JJAS) precipitation change over the Indian region in CTL (2043-2049) relative to the BASE period (2010-2030) and in the single point SO2 injection experiments relative to the CTL simulation during 2043-2049. Percentage changes in the mean over the region is shown in the top right of each panel. The stippling in the panels shows the regions where the changes are significant at the 5% significance level.

3. Monsoon low pressure systems (LPS) over India

One of the striking features of the Indian summer monsoon is the synoptic scale cyclonic disturbances that periodically pass over the monsoon core region (central India), the monsoon low pressure systems (LPS). A significant part of monsoon precipitation in the core monsoon region of India is attributed to these synoptic scale disturbances. These systems usually form over the warm waters of Bay of Bengal (BoB) and propagate northwest ward along the monsoon trough towards the western states Rajasthan/Gujarat. Monsoon LPS are attributed to produce around 60% of monsoon precipitation over core monsoon region of India and about 40% of monsoon precipitation for the country. Many extreme precipitation events and consequent floods in the Indian subcontinent are also attributed to LPS. At the Indian Institute of Science, Bengaluru, India, we study the statistics or climatology of these systems in terms of their frequency, intensity, genesis and tracks in observational records and model (NCAR CESM) simulations (Figure 3). The change in these statistics for boundary condition changes such as alternation in topographical features such as the Himalayas, the Western Ghats, greenhouse gas changes and solar geoengineering are also assessed using climate models.

Publication:

Tresa Mary Thomas, G. Bala, VV Srinivas, 2022: CESM simulation of monsoon low pressure systems over India, International Journal of Climatology, http://doi.org/10.1002/joc.7571

Figure 3 (LPS genesis and track densities): LPS genesis density (i.e., number of genesis locations per year within 500 km radius of a location; top panels) and track density in the ERA5 reanalysis data (right panels) over a 37-year period (1979-2015) and in the present-day control simulation of the NCAR CESM2.1.3 model over a 33-year period. Most LPS form over the northern Bay of Bengal and move northwest wards. The thick black line in the bottom panels denotes the median track in the respective cases. A southward latitudinal shift can be noticed in the genesis and track density and the median track locations in the CESM simulations compared to ERA5 reanalysis.

4. Carbon cycle research

In the industrial era, anthropogenic activities have led to an increase in the concentration of atmospheric CO2 and other greenhouse gases, resulting in global warming. As CO2 is the dominant driver of current climate change, it is important to understand the sources/sinks and the ultimate fate of anthropogenic CO2 emissions. At CAOS, we use Earth System Models (ESMs) to study the carbon cycle and climate processes involved in determining the fate of CO2 emissions and the evolution atmospheric CO2 concentration on decadal to millennial timescales.
In a recent study (2022), we evaluated how the response of climate system to equal amounts (600 PgC) of fossil fuel and LULCC emissions differ, using a set of highly idealized abrupt fossil fuel emissions and global deforestation simulations. In the fossil fuel simulations, after 1000 years, about 20% of the initial atmospheric CO2 concentration perturbation remains in the atmosphere and the climate is about 1°C warmer compared to preindustrial state (Figure 4). In contrast, in the case of deforestation with regrowth, after 1000 years, atmospheric CO2 concentration returns close to preindustrial values as deforested land recovers its carbon over the decades and centuries in the absence of further human intervention. These results highlight the differences in the degree of long-term commitment associated with fossil-fuel versus deforestation emissions.

Figure (4 Climate and carbon cycle response to CO2 emissions from fossil fuel use and deforestation are different): The spatial pattern of the change in surface air temperature (SAT) in the a) DEFORESTION and b) FOSSIL-FUEL emission simulations averaged over the last 100 years of 1000-year simulations relative to the preindustrial state. Abrupt CO2 emissions of 600 PgC were introduced in both the simulations which use the University of Victoria Earth System Climate Model (UVic ESCM). The panels c) and d) are same as a) and b) respectively, but for zonally averaged ocean potential temperatures at different depths of the ocean. In the DEFORESTION simulation, the changes in SAT are either zero or little, while in the FOSSIL-FUEL emission case, SAT change is larger and positive almost everywhere. Similar to the changes in SAT, the changes in ocean temperature are either zero or little in the DEFORESTION case almost everywhere, while they are larger and positive in the FOSSIL-FUEL emission case everywhere except in the northern hemisphere high latitudes.

5. Stable isotopes of water in Indian monsoon precipitation

Stable isotopes of water, particularly δ18O, are used as proxies to reconstruct the past Indian monsoon precipitation based on the climate-dependent fractionation of the water molecule. Further, an identification of the sources of water vapor could help to understand the influence of monsoonal circulation on the δ18O values in precipitation. At the Indian Institute of Science, Bengaluru, India, we recently used the isotope-enabled version of the NCAR CESM modelling framework to estimate the contributions of oceanic and terrestrial water vapor sources to two major precipitation seasons in India—the Southwest monsoon and the Northeast monsoon, and their effects on the δ18O in precipitation (δ18Op). This work involved collaboration with scientists at NCAR.

In our recent work, published in Nature Scientific Report, we found that the two monsoon seasons in India have different dominant sources of water vapor because of the reversal in atmospheric circulation. While the Indian Ocean regions, Arabian Sea, and recycling are the major sources for the Southwest monsoon precipitation during summers, North Pacific Ocean and recycling are the two crucial sources of monsoon precipitation during the Northeast monsoon in the winters (Figure 5). The δ18Op of the Southwest monsoon precipitation is determined by contributions from the Indian Ocean sources and recycling. Though the Northeast monsoon brings relatively much smaller precipitation to India, more negative δ18Op values are simulated due to larger negative δ18Op contributions from the North Pacific. Our results imply that climate model simulations of atmospheric circulation, water vapor sources and δ18O can help to understand paleo monsoon circulations.

Publication:
Thejna Tharammal, G. Bala, and Jesse Nusbaumer, 2023: Sources of Water Vapor and their Effects on Water Isotopes in Precipitation in the Indian Monsoon Region: A Model-Based Assessment, Nature Scientific Reports, 13 (1), 708, https://doi.org/10.1038/s41598-023-27905-9

Figure 5. (Water vapor sources for the Indian summer and winter monsoon precipitation): Relative contributions (in %) of the regional sources to the mean seasonal precipitation in the Indian domain. Left) regional source contributions to the Southwest monsoon precipitation in the summer season, Right) same as left, but for the Northeast monsoon precipitation in the winter season. Indian domain means of precipitation rates for both seasons are shown inside the panels. The figures were created using NCAR Command Language (NCL) Version 6.6.2 (http://www.ncl.ucar.edu/).