Citation: Ganga, S., B.R. Gurjar, R. Kumari, 2011. Urban and country level greenhouse gas emissions and carbon footprints: a comparative study of a megacity, Delhi and India. Journal of Environmental Science and Engineering 53(2), 137-142. Urban and country level greenhouse gas emissions and carbon footprints: a comparative study of a megacity, Delhi and India Sarada Ganga 1, B.R. Gurjar *,2, Ragini Kumari 3 Abstract: This paper describes the contribution and comparison of carbon footprints of megacity Delhi with that of India over the period from 1990 to 2000. Two published studies were taken as base to calculate carbon footprint in terms of CO 2 equivalents (CO 2 -e) by taking into account CO 2, CH 4 and N 2 O emissions mainly from transport, power plants, domestic, industries, agriculture and waste sectors. It is found that carbon footprint have increased more in India (~45%) in comparison to Delhi (~33%) between 1990-2000. However, the average per capita carbon footprint at India level is less than for Delhi. Also, carbon footprint per km area in Delhi is ~ 40 times to that for India. In India (2000) the contribution to carbon footprint s share primarily comes from power plants, industries and agriculture sector whereas it comes from power plants and transport in case of Delhi. Various control measures taken into account in Delhi during 1990-2000 have resulted in decreasing share of CO 2 in the total greenhouse gas (GHG) emissions in comparison to what appears at India level. It indicates that suitable policy measures and norms are required to be implemented at India level to control other GHGs along with CO 2 to reduce net carbon footprints at the country level. Key words: Global warming potential, GHG emissions, CO 2 equivalent 1 Sarada Ganga, Department of Civil Engineering, IIT Roorkee, Uttarakhand # 247667. 2 B.R.Gurjar, Department of Civil Engineering, IIT Roorkee, Uttarakhand # 247667. * Corresponding author: Dr. B.R. Gurjar (Email: brgurjar@gmail.com, phone: +91-9927141416). 3 Dr. Ragini Kumari, Toxics Link, H2-Jungpura Ext., New Delhi # 110014.
Introduction Carbon footprints of an anthropogenic activity, source or sector are defined in several ways. Environmental Technologies Action Plan (ETAP, 2007) 1 has defined the carbon footprint as a measure of the impact of human activities on the environment due to the emission of greenhouse gases (GHGs), which could be measured in CO 2 equivalent (CO 2 -e). Because of their critical role in global warming and climate change, emission control of GHGs is of global concern. Nevertheless, CO 2 alone might not be the good indicator for the policy makers (Kandlikar 1995) 2 while designing policies to control GHG emissions. Indeed it is important to incorporate other radiatively active gases like CH 4 and N 2 O to better estimate in terms of carbon footprints (CO 2 -e). Estimation of carbon footprint is important worldwide because it enables us to visualize and quantify the intensity and impact of GHG emissions in terms of global warming potential and their relative contribution to regional and global climate change (IPCC, 2001) 3. Carbon footprints of an urban area or a nation may be quite different due to large difference in scale of economy and infrastructure, which directly influence the emission of GHGs. Among urban agglomerations, megacities (cities having population equal to or more than 10 million) have peculiar dynamics on account of shear large number of population, high consumption of resources, and scale of economy. This paper presents carbon footprint of GHG emissions in megacity Delhi and its evaluation in comparison to carbon footprint of GHG emissions in India. Estimation of carbon footprint for Delhi was based on the GHG emissions estimates carried out by Gurjar et al. (2004) 4 and for India it was based on Garg et al. (2006) 5.The degree of urbanization, energy consumption, and hence sources of GHG emissions from Delhi differs that from average rate of urbanization in India. This is also reflected in the trend and emission contributions from different sectors (e.g., transport, power plants, domestic, industries, agriculture and waste) of Delhi and India in the respective carbon footprints. Further, to see the impact of urbanization, carbon footprints have also been expressed in terms of per capita and per unit area of carbon footprints. Moreover, we also estimated and compared CO 2 emission with CO 2 -e of India and Delhi. Methodology Estimation of carbon footprint (CO 2- e) of India and mega city Delhi Following the definition ETAP (2007) 1, we have estimated carbon footprints in terms of CO 2 equivalent (CO 2 -e). To achieve this, we have converted emissions of GHGs (CO 2, CH 4, and N 2 O) released from Delhi in terms of CO 2 -e based on their Global Warming Potential (GWP). Here, GWP of a greenhouse gas (GHG) is defined as the ratio of the timeintegrated (100-years) radiative forcing exerted by instantaneous release of 1 kg of a trace substance (CO 2, CH 4, and N 2 O) relative to that of 1 kg of a reference GHG (CO 2 ) (IPCC, 2001) 3. The GWP values used for the estimation of carbon footprints in terms of CO 2 -e is given in Table 1. Table 2 shows the baseline data of annual emissions (Tg/yr) of GHGs (CO 2, CH 4 and N 2 O) in India (Garg et al., 2006) 5 and Delhi (Gurjar et al., 2004) 4, which have been used to estimate carbon footprints (CO 2- e) for India and Delhi respectively. The following equation has been used to compute the CO 2 -e: CO2 -e (Ei ) (GWP)... (1) Where, CO 2 -e = Carbon dioxide equivalent in Tg 0
E i = Emissions of GHGs (CO 2, CH 4, N 2 O) for year i in Tg GWP = Global Warming Potential Sector specific GHG emissions in India and megacity Delhi Based on the GHG emissions given in Gurjar et al. (2004) 4 and (Garg et al., 2006) 5 we have analyzed the relative GHG contribution of different sectors like transport, power plants, domestic, industries, agriculture and waste in Delhi and India respectively. It is observed that the major contributors to the CO 2 emissions in India were power plants (38%) and industry (32%) in 1990 and its relative share in 2000 changed to power plants (50%) and industry (26%) as given in Fig. 1. In case of Delhi, power plants alone contributed 60% of CO 2 followed by transport (27%) in the year 1990. By the year 2000 emission of CO 2 from power plants in Delhi reduced to 48% whereas about 12% of increase was noticed in transport sector (Fig. 2). Thus, although power plants are major emitters of CO 2 in both Delhi and India level, these are followed by industries in case of India whereas transport is the second most contributing sector of CO 2 in Delhi. CH 4 emission primarily comes from agriculture sector (76-79%) in India (Fig. 1) whereas waste is the predominant source (84-86%) in Delhi (Fig. 2). Furthermore, in 1990 the major contributor to the N 2 O emissions in India was agriculture sector (80%), and was same for Delhi with lower share (59%). Even in 2000 agriculture sector remains dominating source of N 2 O emission but its share has increased to 83% in India level (Fig. 1), whereas slight decline (51%) was noticed for the Delhi (Fig. 2). Moreover, industries emit almost similar share (~5%) of N 2 O in both India and Delhi. However, unlike at India level, the transport and domestic sectors in Delhi jointly make significant contribution (25-28%) to N 2 O emissions. Per capita and per unit area (sq. km) carbon footprints (CO 2 -e) of India and megacity Delhi Total carbon footprints (CO 2 -e) obtained from India and mega city Delhi have further been converted in terms of per capita and per unit area carbon footprints to see how emission patterns of GHGs and their CO 2 -e differ from each other at an urban and national scale. Population data used for this calculation is given in Table 3. From Table 3, we can see that the population growth in India was 17% whereas Delhi has grown by 50% between years 1990 to 2000. This shows how rapidly population is expanding in a megacity making it a characteristic feature of large urban centers. Like per capita carbon footprints, CO 2 -e emission estimation in terms of per unit area is other important indicator to show how the spatial emission pattern of a megacity is different than India as a whole. Interestingly, Delhi has very small area share (0.045%) to India but has comparatively large share in population (1.32%) in year 2000. Results and Discussion Comparison of estimated carbon footprints (CO 2 -e) of India with megacity Delhi Total annual carbon footprints Eq. 1 has been used to estimate carbon footprints in terms of CO 2 equivalents (CO 2 - e). Carbon footprints in India have increased from about 1040 Tg to 1511 Tg (~45%) between the year 1990 to 2000, whereas in Delhi it has increased from 20 Tg to 27 Tg (~33%) during same period (Table 4). Thus, the share of Delhi alone in the total carbon footprints of India has been about 1.8%. However, when India s carbon footprint has 1
increased at the annual growth rate of 4.5 %, it was about 3.3% for Delhi. This shows that growth rate in GHG emissions in highly urbanized and densely populated Delhi have increased at slower pace in comparison to the GHG emissions at national scale. This also indicates the positive impact of various control measures that have been implemented in Delhi to curb GHG emissions and resulting carbon footprint. Moreover, this illustrates the need for taking appropriate measures to check the accelerating growth rate of GHG emission and carbon footprints at the country level. Annual per capita carbon footprints The average per capita carbon footprints (or CO 2 -e emission) at India level is about 1.4 Mg, which is 33% less than that of Delhi (2.1 Mg) (Table 4). Nevertheless, per capita carbon footprints (CO 2 -e) in India have increased from 1.2 Mg to 1.5 Mg between 1990-2000, whereas it has decreased from 2.3 Mg to 2.0 Mg in Delhi during the same period of time (Table 4). There are two reasons behind this opposite trend in growth of per capita carbon foot prints: the faster annual growth rate of population in Delhi (5%) as compared to India (1.7%) (Table 3) and slow annual growth rate of CO 2 -e emissions in Delhi (3.5%) in comparison to India (4.5%). Annual per unit area carbon footprints The average per unit area emission intensity of carbon footprints is about 390 Mg/sq km for India whereas it is much higher (15700 Mg/sq km) for Delhi. Thus, in terms of unit area carbon footprints, Delhi is about 40 times more GHG emitter in terms of CO 2 -e as the fuel consumption and emissions released from anthropogenic activities of densely populated Delhi take place in relatively smaller area. The estimated annual per unit area carbon footprints (CO 2 -e) for India has increased from 315 Mg/sq km to 458 Mg/sq km between year 1990 to 2000 (Table 4), whereas it is much high for the Delhi and has increased from 13472 Mg/sq km to 17894 Mg/sq km between the same time period (Table 4). Comparison of sector specific Carbon footprints (CO 2- e) The methodology described before has also been used for the estimation of sector specific carbon footprints in terms of CO 2 -e. Relative contribution of these sectors in carbon footprints are given in Fig. 3, whereas Table 5 gives insight into change in absolute values for India and Delhi. In 1990, power and industrial sectors jointly were the largest contributors (41%) to the carbon footprints (CO 2- e) in India whereas agriculture contributed about 35% of total CO 2 -e. In 2000, the joint share of power and industrial sectors in total CO 2 -e emissions increased to 52% whereas the contribution of agriculture decreased to 26%. This clearly shows that India is steadily transforming from an agrarian (i.e. agriculture / farming based) to industrial society (Fig. 3). A carbon footprint (CO 2 -e) of power plant sector in India has increased 2.24 times (231Tg to 517Tg) from 1990 to 2000 (Table 5). Also, emission from this sector is more (1.7 times) in the first 5 years span (1990-1995) as compared to next 5 years span (1.32 times). Transport sector was holding second position and rise was from 87 Tg to 126 Tg from 1990 to 2000, followed by power plants in terms of carbon foot prints. Increment rate from this sector was more between 1995 to 2000 (1.28 times) as compared to 1990 to 1995 (1.13 times). Other sectors include industry, waste and additional miscellaneous sectors. An increment of about 1.3 times and 1.08 time was seen from agriculture and domestic sectors. In 1990 in Delhi CO 2- e emission contribution primarily comes from power plants (50%), followed by transport sector (24%) and by 2000 power plants contribution remains 2
the same whereas share of transport sector increased to 33% (Fig. 3) indicating the increasingly important role of transportation system in Delhi s economy. Though the total contribution of carbon footprint from industrial sector was less but its rate has increased more than 2 times in Delhi. Whereas the relative contribution as well as rate of rise was more in case of transport sector (1.88 times) between 1990 to 2000 (Table 5). Contribution (%) of respective GHGs in the carbon footprints (CO 2 -e) Fig. 4 shows that share of CO 2, CH 4 and N 2 O in carbon footprints at India level varies from 59-68%, 36-27% and 5%, respectively. This is another indicator of the transition of India from agriculture based society towards industrial one as fossil fuels constitute the main source of CO 2 emissions (Fig. 4). In Delhi, CO 2 contributed about 84% followed by CH 4 (14%), and N 2 O (2%) to the total annual carbon footprint (Fig. 4). Though the contribution to carbon footprints from Delhi was 84% from CO 2 but its rate of acceleration has reached a constant level because of various policy measures. Comparison of CO 2 emission with carbon footprints (CO 2 -e) In Fig. 5 we did inter comparison of emission trends of CO 2 with CO 2 -e at Delhi level and India as well. The relative share of CO 2 to carbon footprints (CO 2 -e) decreased from 1.69 to 1.46 times whereas it was ~1.32 times in Delhi from 1990 to 2000 as a result of faster rate of growth of CO 2 as compare to other GHG s in India. Controlled rate of CO 2 emission for Delhi can be indicative of various policies implemented in Delhi whereas steeper rise at India level is pinpointing of expansion of urbanization on the country level. It indicates that stringent laws or appropriate policy interventions need to be enforced at the India level to control other GHGs so that the rate of rise of total carbon footprints at India level can be stabilized. Limitations and further scope of the study 1. There are few differences in assumptions and sub-sectors covered by Garg et al. (2006) 5 for India and Gurjar et al. (2004) 4 for Delhi, which are the source of baseline data: (i) For example, Gurjar et al. (2004) 4 considered only road under the head of transport sector while Garg et al. (2006) 5 has taken not only roads but also railways, shipping and aviation in it. (ii) In case of Delhi GHG emissions from industry sector are very less (~5%) which might be because of lack of consideration of various types of industries (Gurjar et al., 2004) 4. Whereas, in case of India, the industrial sector includes iron steel, cement and other industries. GH(>30%). (iii) For both India (Garg et al., 2006) 5 and Delhi (Gurjar et al., 2004) 4, agricultural sector considered activities such as enteric fermentation, paddy cultivation, manure management, agricultural crop residue burning and soil emissions. But there is difference in GHG specific emission considerations. (iv) In India miscellaneous sectors were covered whereas it is lacking for Delhi. 2. We have considered only CO 2, CH 4 and N 2 O in the present study to calculate carbon footprints whereas there is other GHGs as well (e.g., hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF 6 )) which we have not been taken into account. 3
3. Since, baseline data for Delhi was not available to us for years later than 2000, so it s possible that these trends might have changed for post-2000 period. Because of above limitations, there could be uncertainty in our estimations of carbon footprints for India and Delhi. 4. When seen in the context of Delhi, there is much scope to reduce carbon footprint at India level by reducing GHG emissions. Options to reduce GHG emissions include end use efficiency improvement, fuel switches, and efficiency improvement of existing and new power plants (Kroeze et al., 2004) 10. Nevertheless, since GHGs emissions are directly linked to economic growth, India s economic activities will necessarily result in higher GHG emissions in future. The CO 2 equivalent emissions from India are projected to increase up to 3000 million tonnes by 2020 and any constraint will hamper the economic development (Garg et al., 2004; Sharma et al., 2006) 11,12. Such interests of conflict call for a detailed study to assess and evaluate the best technological and policy interventions so that reduction in GHG emissions (and thus in carbon footprint) can be achieved without compromising on economic development in India. Conclusion Emission contribution of carbon footprint (CO 2 -e) of megacity-delhi was compared with that of India for the period 1990-2000. Carbon footprints increased ~45% in India whereas ~33% in Delhi between the year 1990 to 2000. The share of Delhi alone contributes ~ 1.8% to the total carbon footprints of India. Rise in per capita carbon footprints (from 1.2 Mg to 1.5 Mg) in India was noticed whereas it has decreased (from 2.3 Mg to 2.0 Mg) in Delhi during 1990 to 2000. The estimated annual per unit area carbon footprints (CO 2 -e) for India has increased from 315 Mg/sq km to 458 Mg/sq km whereas it is much high for Delhi and has increased from 13472 Mg/sq km to 17894 Mg/sq km between year 1990 to 2000. Thus, in terms of unit area carbon footprints, Delhi is about 40 times more GHG emitter in terms of CO 2 -e. In India (1990), power and industrial sectors jointly were the largest contributors (41%) to the carbon footprints (CO 2- e) followed by agriculture ~ 35% of total CO 2 -e. In 2000, the joint share of power and industrial sectors in total CO 2 -e emissions increased to 52% whereas the contribution of agriculture decreased to 26% in India. In 1990 in Delhi CO 2- e emission contribution primarily comes from power plants (50%) followed by transport sector (24%). By 2000 power plants contributions has decreased to 40% whereas share of transport sector increased to 33%. The relative share of CO 2 to carbon footprints (CO 2 -e) decreased from 1.69 to 1.46 times whereas it was ~1.32 times in Delhi from 1990 to 2000 as a result of faster rate of growth of CO 2 as compared to other GHG s in India. Policy makers need to pay attention in making stringent laws or appropriate policy interventions to control other GHGs like CH 4 and N 2 O in agriculture based country like India whereas control in CO 2 emission can t be neglected as a matter of expansion in industrialization. Acknowledgements First author would like to thank MHRD, India for giving scholarship to carry out this study as a partial fulfillment of M. Tech seminar. Second author thanks the Max Planck Society, Munich, and Max Planck Institute for Chemistry, Mainz, Germany, for their support received through the Max Planck Partner Group for Megacities & Global Change, IIT Roorkee, India, during the preparation of this manuscript. We also thank anonymous reviewer for his valuable comments to help us improve the quality of manuscript. 4
References (1) ETAP (Environmental Technologies Action Plan), The Carbon Trust Helps UK Businesses Reduce their Environmental Impact, Press Release (2007). URL: < http://ec.europa.eu/environment/etap/pdfs/jan07_carbon_trust_initiative.pdf > (2) Kandlikar, M., The relative role of trace gas emissions in greenhouse abatement policies, Energy Policy, 23(10), 879-883 (1995). (3) IPPC (Intergovernmental Panel on Climate Change), Climate Change 2001: The Scientific Basis. Intergovernmental Panel on Climate Change, Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., Vander Linden, P.J., Dai, X., Johnson, C.A. and Maskell, K., (eds.). Cambridge University Press. Cambridge, U. K (2001). (4) Gurjar, B.R., Aardenne, J.A., Lelieveld, J. and Mohan, M., Emission estimates and trends (1990-2000) for mega city Delhi and implications, Atmospheric Environment, 38, 5663-5681 (2004). (5) Garg, A., Shukla, P.R., Ghosh, D. and Kapshe, M., The sectoral trends of multigas emissions inventory of India, Atmospheric Environment, 40,.4608-4620 (2006). (6) EPA (Environmental Protection Agency), Inventory of U.S. GHG emissions and sinks: 1990-2006, EPA, U.S, 1-473 (2008). (7) IGES (Institute of Global Environmental Strategies), Energy and emission in south Asian mega-cities: study on Kolkata, Delhi and Manila. pp.1-11 (2000-2003).URL:<http://www.iges.or.jp/en/ue/activity/mega-city/article/htm/far47.htm > (8) Garg, A., Bhattacharya, S., Shukla, P.R. and Dadhwal, V.K., Regional and sectoral assessment of greenhouse gas emissions in India, Atmospheric Environment, 35, 2679-2695 (2001). (9) Das, A. and Parikh, J., Energy Conversion and Management: Transport Scenarios in two Metropolitan cities in India:Delhi and Mumbai, Energy Policy, 45, 2603-2625 (1997). (10) Kroeze, C., Vlasblom, J., Gupta, J., Boudri, C. and Blok, K., The power sector in China and India: greenhouse gas emissions reduction potential and scenarios for 1990 2020, Energy Policy, 32, 55-76 (2004). (11) Garg, A., Shukla, P. R. and Kapshe M., Future methane and N2O emissions for India. In Proceedings of the Natcom Workshop on Scenarios and Future Emissions held at Indian Institute of Management on July 22, 2003, Ministry of Environment and Forests, Government of India (2004). (12) Sharma, S., Bhattacharya, S. and Garg, A., Greenhouse gas emissions from India: A perspective, Current Science, 90, 326-333 (2006). 5
Fig. 1: Sector specific emission contribution (%) of GHGs (CO 2, CH 4 and N 2 O) for India over 1990-2000 Fig. 2: Sector specific emission contribution (%) of GHGs (CO 2, CH 4 and N 2 O) for Delhi over 1990-2000 6
Fig. 3: Comparison of sectoral carbon footprint (CO 2 -e) emission trends between 1990 and 2000 in India and Delhi. Fig. 4: Comparison of contribution (%) of GHGS in the carbon footprints (CO2-e) emission in India and Delhi between year 1990 and 2000. 7
(a) India Fig. 5: Comparison of CO 2 with carbon footprint (CO 2 -e) emission trends between 1990 and 2000 in India and Delhi Table 1: Global warming potential (GWP) of different GHGs used in the present study GHGs Atmospheric lifetime (year) GWP CO 2 50-200 1 CH 4 9-15 21 N 2 O 120 310 Source: EPA, 2008 6. Where, GHGs: green house gases, GWP: Global warming potentials Table 2: Baseline data of GHG emissions (Tg) for India and megacity Delhi for years 1990, 1995 and 2000. Emissions India a (Tg) Delhi b (Tg) 1990 1995 2000 1990 1995 2000 CO 2 615 849 1032 16.80 19.46 22.04 CH 4 17.92 18.85 19.61 0.13 0.16 0.19 N 2 O 0.158 0.185 0.217 0.0014 0.0016 0.017 Where, a Garg et al., (2006) 5, b Gurjar et al., (2004) 4, unit of emission are expressed in terms of Tg=Tera-gram (1Tera g = 10 12 g) 8
Table 3: Population and area of India and megacity Delhi taken into account to calculate carbon footprints in respective terms (1990-2000) Data India Delhi 1990 1995 2000 1990 1995 2000 Population (M) 855 a 930 a 1000 a 8.8 a 11.0 a 13.2 a Area (sq km) 3301581 b 1485 c Where, a IGES (2000-2003) 7, unit of population expressed in terms of M-Million (10 6 ); b Garg et al. (2001) 8, area for India, unit expressed in sq km; c Das, et al.(1997) 9, area for Delhi, unit expressed in sq km; Table 4: Comparison of estimated carbon footprint (CO 2 -e) of India with megacity Delhi (1990-2000) in terms of total annual (Tg), per capita (Mg/person), and per unit area (Mg/sq km). Emissions India Delhi 1990 1995 2000 1990 1995 2000 Total (Tg) 1040.30 1302.20 1511.08 20.02 23.39 26.59 Per capita CO 2 -e 1.22 1.40 1.51 2.28 2.13 2.01 (Mg/person) Per unit area CO 2 -e 315.09 394.42 457.68 13472 15740 17894 (Mg/sq km) Where, Mg, unit of emission are expressed in Mega-gram (1 Mg = 10 6 g) 9
Table 5: Comparison of sector specific carbon footprint (CO 2 -e) in India and megacity Delhi (1990-2000) Sectors India a (Tg) Delhi b (Tg) 1990 1995 2000 1990 1995 2000 Power plants 231.00 392.00 517.00 10.11 10.30 10.66 Transport 87.00 98.60 125.80 4.71 6.71 8.84 Domestic 34.02 35.07 36.96 2.10 2.64 2.68 Industry 201.17 243.79 272.72 0.02 0.03 0.04 Agriculture 361.31 379.76 390.39 0.61 0.66 0.68 Waste 24.33 27.37 31.88 2.47 3.06 3.69 Miscellaneous 101.26 125.23 135.88 - - - Total (Tg) 1040.09 1301.82 1510.63 20.02 23.40 26.59 Where, a Garg et al., (2006) 5, b Gurjar et al., (2004) 4, -: Not applicable, Tg, unit of emission are expressed in terms of Tg=Tera-gram (1Tg = 10 12 g) 10