T.V. Ramachandra^1,2,3,*, Bharath H. Aithal¹, K. Sreejith¹

¹Energy and Wetlands Research Group, Centre for Ecological Sciences(CES), Indian Institute of Science, Bangalore 560 012, INDIA.
²Centre for Sustainable Technologies,
³Centre for infrastructure, Sustainable Transportation and Urban Planning (CiSTUP)
^*Corresponding author: T.V. Ramachandra, cestvr@ces.iisc.ernet.in
Web: http://wgbis.ces.iisc.ernet.in/energy

Conclusion

India is currently second most populous country in the world and third biggest greenhouse gas emitter contributing about 5.3% of the total global emissions. Countries such as India which is one of the fast growing economies in the world , with  higher energy consumption for various activities with increase in transport sector emissions with scale of rapid and uncontrolled urbansiation and quest of higher living standards are eventually the causes of GHG emissions in todays’ scenario. The quality of air in the major Indian cities which affects the climatic conditions as well as health of the community is a major environmental concern. Higher levels of energy consumption have contributed to the degradation of the environment. Chennai emits 4.79 tonnes of CO2 equivalent emissions per capita, the highest among all the cities followed by Kolkata which emits 3.29 tonnes of CO2 equivalent emissions per capita. Also Chennai emits the highest CO2 equivalent emissions per GDP (2.55 tonnes CO2 eq/Lakh Rs.) followed by Greater Bangalore which emits 2.18 tonnes CO2 eq/Lakh Rs. GHG Footprint of all the major cities in India helps in improving national level emission inventories. In the last few years, the popularity of GHG Footprint has grown resulting in the major metropolitan global cities to estimate their greenhouse gas emissions and thereby framing regulations to reduce the emissions. The data regarding emissions from different sector helps the policy makers and city planners to devise mitigation strategies focusing on the particular sector which helps in improving the environmental conditions within the city. Implementation of emission reduction strategies in cities also helps in gaining carbon credits in the global markets, which has been an outcome of increased awareness about greenhouse gas emissions. GHG footprint of major cities in India sector-wise would help the planners in implementing appropriate mitigation measures.

• Electricity consumption: The calculation of greenhouse gas emissions from commercial and other (public lighting, advertisement hoardings, railways, public water works and sewerage systems, irrigation and agriculture) sectors shows that energy consumption in commercial sector is one of the major contributor of emissions in cities, which accounts for 15-24% of total emissions in cities, except for Hyderabad and Ahmedabad where it contributes 7.5% and 12% of the total emissions. Delhi and Greater Mumbai are the two major cities with an emission of 7448.37 Gg and 5341.34 Gg CO2 equivalents respectively during 2009. This study also accounts for emissions from power plants located within the city. The results highlight that energy consumption in commercial sector in cities are a major source of emissions. It becomes important especially in such scenarios  for adopting and using power plants that have almost zero conversion emissions based on renewable energies such as wind, solar etc.,
• Domestic sector: The study reveals that domestic sector causes majority of the emissions in all the major cities due to the use of fossil fuels like LPG, kerosene and PNG for cooking purposes. Fossil fuels used for cooking purposes in household’s cause indoor air pollution. Consumption of electricity in domestic sector for lighting, heating and household appliances also share a major portion of emissions. It is calculated that domestic sector resulted in emissions of 11690.43 Gg of CO2 equivalents (~30% of the total emissions) in Delhi which is the highest among all the cities followed by Chennai and Greater Mumbai which emits 8617.29 Gg (~39% of total emissions)  and 8474.32 Gg of CO2 equivalents (~39% of total emissions) respectively.  GHG emissions from domestic sector in cities show the scope for cleaner fuels for cooking through the renewable sources - solar energy for water heating and other household purposes.
• Transportation sector: Road transport is another chief sector other than domestic sector causing major portion of emissions in the cities. From the results obtained, major emitters are Delhi and Greater Bangalore which emits 12394.54 Gg and 8608 Gg of CO2 equivalents respectively. Transportation sector is a major source of emissions when city level studies are carried out. Emissions from CNG vehicles in few of the cities are calculated along with the fuel consumption for navigation in the port cities. Lesser polluting fuels like LPG and CNG can be made compulsory in major cities, phasing out older and inefficient vehicles and extensive public transport helps in reducing pollution.
• Industrial sector: Industrial sector contributes approximately 10-20% of the total emissions in all the major cities. In this study electricity consumption in industries is taken for all the cities and also emissions from major industries located within the city boundary. Chennai city is found to be the highest emitter, which emits 4472.35 Gg of CO2 equivalents. There is insufficient data for medium and small scale industries located within the cities.
• Agriculture and livestock activities: Due to the increasing urbanization, there are not much agricultural related activities and animal husbandry practiced in the major metropolitan cities. This sector accounts less than 3% of total emissions among the cities. Delhi and Greater Bangalore emits 961 Gg and 258.6 Gg of CO2 equivalents due to livestock management and agricultural activities. The results prove that the agricultural practices are decreasing in cities due to increase in the urban growth. There has also been suggestion that agricultural lands that are existent can be made to emit lower carbon by diversifying crop rotation systems significantly lowers GHG footprint [Yang et al., 2014)
• Waste sector: Management and treatment of solid and liquid waste in cities results in emissions. This sector shares 3-9% of total emissions resulting from the cities. Delhi and Greater Mumbai emits the major amount of emissions, 2232 Gg and 1928 Gg of CO2 equivalents when compared with other cities. This showed that waste sector accounts for considerable amount of greenhouse gas emissions when city level studies are carried out.

6. Scope of further research