skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A brief survey on climate change effects on the Indian Monsoon

Abstract

Each year, Indian summer monsoon season begins in June and ends in September. Surface winds blow from the southwest during this season. The Indian summer monsoon typically covers large areas of India with western and central India receiving more than 90% of their total annual precipitation during this period, and southern and northwestern India receiving 50%-75% of their total annual rainfall. Overall, monthly totals average 200-300 mm over the country as a whole, with the largest values observed during the heart of the monsoon season in July and August. In all total, India receives about 870 mm of rainfall in a normal summer monsoon season. This summary discusses the effects of climate change on the frequency, mean rainfall, duration and the variability of the Indian Monsoon. East Asian Monsoon in the southeastern part of Asia is not discussed in this summary. Changes in monsoon characteristics are mainly inferred from climate model simulations submitted to the Intergovernmental Panel on Climate Change (IPCC)'s Fourth Assessment Report (AR4). It should be cautioned that there is a large range in the results from these models. For instance, the range of mean monsoon precipitation as simulated by the AR4 models over India is from 500more » mm to 900 mm for the present-day climate (Kirpalani et al. 2006).« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1036853
Report Number(s):
UCRL-TR-227839
TRN: US201207%%33
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; ASIA; CLIMATE MODELS; CLIMATES; CLIMATIC CHANGE; INDIA; MONSOONS; PRECIPITATION; SEASONS

Citation Formats

Bala, G. A brief survey on climate change effects on the Indian Monsoon. United States: N. p., 2007. Web. doi:10.2172/1036853.
Bala, G. A brief survey on climate change effects on the Indian Monsoon. United States. doi:10.2172/1036853.
Bala, G. Tue . "A brief survey on climate change effects on the Indian Monsoon". United States. doi:10.2172/1036853. https://www.osti.gov/servlets/purl/1036853.
@article{osti_1036853,
title = {A brief survey on climate change effects on the Indian Monsoon},
author = {Bala, G},
abstractNote = {Each year, Indian summer monsoon season begins in June and ends in September. Surface winds blow from the southwest during this season. The Indian summer monsoon typically covers large areas of India with western and central India receiving more than 90% of their total annual precipitation during this period, and southern and northwestern India receiving 50%-75% of their total annual rainfall. Overall, monthly totals average 200-300 mm over the country as a whole, with the largest values observed during the heart of the monsoon season in July and August. In all total, India receives about 870 mm of rainfall in a normal summer monsoon season. This summary discusses the effects of climate change on the frequency, mean rainfall, duration and the variability of the Indian Monsoon. East Asian Monsoon in the southeastern part of Asia is not discussed in this summary. Changes in monsoon characteristics are mainly inferred from climate model simulations submitted to the Intergovernmental Panel on Climate Change (IPCC)'s Fourth Assessment Report (AR4). It should be cautioned that there is a large range in the results from these models. For instance, the range of mean monsoon precipitation as simulated by the AR4 models over India is from 500 mm to 900 mm for the present-day climate (Kirpalani et al. 2006).},
doi = {10.2172/1036853},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 06 00:00:00 EST 2007},
month = {Tue Feb 06 00:00:00 EST 2007}
}

Technical Report:

Save / Share:
  • The overall goal of this project is to assess the ability of the CMIP3/5 models to simulate the Indian-Ocean monsoon systems. The PI along with post-docs investigated research issues ranging from synoptic systems to long-term trends over the Asian monsoon region. The PI applied diagnostic tools such as moist static energy (MSE) to isolate: the moist and radiative processes responsible for extended monsoon breaks over South Asia, precursors in the ENSO-monsoon association, reasons for the drying tendency over South Asia and the possible effect on tropical Indian Ocean climate anomalies influencing certain aspects of ENSO characteristics. By diagnosing various observationsmore » and coupled model simulations, we developed working hypothesis and tested them by carrying out sensitivity experiments with both linear and nonlinear models. Possible physical and dynamical reasons for model sensitivities were deduced. On the teleconnection front, the ability of CMIP5 models in representing the monsoon-desert mechanism was examined recently. Further more, we have applied a suite of diagnostics and have performed an in depth analysis on CMIP5 integrations to isolate the possible reasons for the ENSO-monsoon linkage or lack thereof. The PI has collaborated with Dr. K.R. Sperber of PCMDI and other CLIVAR Asian-Australian monsoon panel members in understanding the ability of CMIP3/5 models in capturing monsoon and its spectrum of variability. The objective and process-based diagnostics aided in selecting models that best represent the present-day monsoon and its variability that are then employed for future projections. Two major highlights were an invitation to write a review on present understanding monsoons in a changing climate in Nature Climate Change, and identification of an east-west shift in observed monsoon rainfall (more rainfall over tropical western Pacific and drying tendency over South Asia) in the last six decades and attributing that shift to SST rise over the tropical western Pacific. On the training of post-doctoral scientists: the PI spent considerable amount of time and efforts in introducing the post-docs into climate modeling and designing the numerical experiments. With training provided and knowledge gained, post-docs worked in the project obtained long term positions elsewhere. The PI also enjoyed the experience in managing the works and educating work ethics to the younger generation. Based on the research achievements and publications, the PI gave invited talks in major international monsoon conferences/workshops, and gave lectures in various research organizations in the last six years. Finally, during the project period, the PI attended all the DOE organized PIs meeting and presented the major results. Some of the major implications of the project include: (i) Sustained observational efforts are necessary to monitor the three-dimensional moisture distribution over the Asian monsoon region that would aid in better understanding, modeling and predicting severe monsoons well in advance and (ii) process-based diagnostics lead pathways for model improvements.« less
  • Daily moderate rainfall events, which constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 through 2005. On the other hand, mean and extreme near-surface daily temperature during the monsoon season have increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4) and prescribed land cover of years 1950 and 2005, it is demonstrated that part of the changes in moderate rainfall events and temperature have been caused by land-use/land-cover change (LULCC), which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over centralmore » India coincides with the region of decrease in forest and increase in crop cover. Our results also show that LULCC alone causes warming in the extremes of daily mean and maximum temperatures by a maximum of 1–1.2 °C, which is comparable with the observed increasing trend in the extremes. Decrease in forest cover and simultaneous increase in crops not only reduces the evapotranspiration over land and large-scale convective instability, but also contributes toward decrease in moisture convergence through reduced surface roughness. These factors act together in reducing significantly the moderate rainfall events and the amount of rainfall in that category over central India. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures over the Indian Ocean. As a result, enhanced warming at the surface and greater decrease in moderate rainfall events over central India compared to the earlier set of simulations are noticed. Results from these additional experiments corroborate our initial findings and confirm the contribution of LULCC in the decrease in moderate rainfall events and increase in daily mean and extreme temperature over India. Therefore, this study demonstrates the important implications of LULCC over India during the monsoon season. Although, the regional climate model helps in better resolving land–atmosphere feedbacks over the Indian region, the inferences do depend on the fidelity of the model in capturing the features of Indian monsoon realistically. Lastly, it is proposed that similar studies using a suite of climate models will further enrich our understanding about the role of LULCC in the Indian monsoon climate.« less
  • The impact of CO/sub 2/-induced increases in ambient temperature is predicted to result in an overall reduction in animal productivity, although animal productivity may increase in some parts of the world. New technologies will be needed to maintain or overcome the adverse effects of climate that are predicted. The effects of temperature (and other associated changes in climate) impact directly on the physiology of the animals as well as indirectly through changes in parasites, diseases, forages, crops and soils. The purpose of this paper is to identify the researchable issues which will permit animals to maintain and perhaps increase theirmore » food production capacity and efficiency in spite of potential increases in ambient temperature. In order for animal agricultural systems to maintain or increase efficiency and productivity in the face of altered climate, additional knowledge must be gained in understanding the multiplicity of pathways whereby weather exerts its effects on the biological components involved in animal agriculture. Research needed to permit animals to cope with increasing ambient temperatures are described for the following topics: animal productivity; nutrition; endocrinology; reproduction; acclimation and behavior; genetics; animal health; environmental modification and housing; adaptation, yield and quality of primary feed producing plants; soil resources for animal feed production; international aspects; systems management; and economics. The research approaches suggested range from highly detailed physiological and biochemical studies in environmentally controlled animal chambers to studies of animals managed in extensive grazing conditions.« less
  • Three algal bioassay experiments were conducted from March 1992 through September 1993 in an area of Lake Mead that has experienced problems associated with severe nutrient enrichment. The first experiment determined the effects of elevated CO2 (700 ppm) (2xCO2), vs ambient CO2 on the natural algal assemblage without nutrient enrichment. The second experiment determined the effects of 2xCO2 on nutrient enriched bioassays and if nutrients were limiting. The third experiment examined elevated temperatures and 2xCO2. Nested climate models were used to predict changes in water temperatures and thermocline development in Las Vegas Bay. The lake model predicted an increase inmore » mean water temperatures of 1.8 deg under a 2xCO2 scenario. A thermocline definition of 1 deg. C change per 2-m depth was applied to water temperatures developed by a lake model coupled to nested general circulation and regional-scale atmospheric models in 3-year simulations of the current and double-CO2 climates.« less
  • Plant pests and their community of biotic cohorts respond to climatic changes, whether temporal aberrations or long term shifts. How they respond depends on the magnitude of the change and the ability of the species to tolerate or adapt to the new environment. Scientists see several climatological scenarios concerning the increase of atmospheric CO/sub 2/ and ambient temperature. Those who foresee a slow incremental raising of temperatures base their predictions mainly on the available empirical evidence and the notion that long term weather is basically a cyclical phenomena that continually adjusts and readjusts through time. The other scenario interprets themore » available empirical data as a gradual buildup that pushes the climatic picture towards a threshold or a trigger point that, once arrived at, is irreversible and dramatic. This paper explores the possible climatic scenarios as they relate to the ecological principles that affect pest abundance and the distribution and impact on domestic and international agriculture.« less