Air Pollution as a Climate Forcing: A Workshop
Day 1 Presentations
Indian Inventory of Climate Forcing Pollutants
National Physical Laboratory, New Delhi, India
There have been, in the last decade, several major efforts in South Asia, especially in India, relating to the inventories of GHG emissions and other pollutants. The first in India was a National Methane Campaign in 1991 (MAC-91) on methane emission from paddy fields using a network of carefully planned observing sites covering the major rice growing areas of the country. In the late nineties an international program called ALGAS (Asia Least Cost Greenhouse Gas Emission Strategy) was carried out in which twelve Asian countries including India and China, the two largest emitter countries, have also participated . The focus of this program was on the preparation of inventories of three major greenhouse gases; CO2, CH4 and N2O for the base year 1990 and a projection for 2025 using various socio-economic options besides identification of low cost options for mitigation. The third was the Methane Asia Campaign (MAC-98) which was undertaken in 1998 and 1999 to refine estimates of methane emissions from paddy fields in the context of earlier findings of low emission values. The fourth was the widely acclaimed Indian Ocean Experiment (INDOEX) which was an extensive programme targeting measurements of aerosol loading in the atmosphere over the Indian Ocean region in northern winter and the resulting radiative forcing. The main campaign was carried out during 1999 following trial pre-campaign in 1998. The participating institutes in INDOEX belonged to India, USA, Europe, Mauritius and Maldives. The fifth is a programme on emissions of greenhouse gases and other pollutants from seven Asian mega-cities (viz. Delhi, Kolkatta, Manila, Tokyo, Seoul, Beijing and Shanghai) sponsored by Asia Pacific Network for Global Change Research (APN). A very recent effort concerns the study of three categories of environmental related health impacts: climate change and malaria, aerosols and respiratory diseases, and UVA and UVB and corneal damages and cataracts.
The GHG inventories prepared under ALGAS (for 1990) showed that emission from the participating countries account only for 12% of the global 1990 GHGs emissions, with nearly 80% of this from India and China.
In the South Asian region, which is only 3% of the total world area but populated by about 21% of the world population, the GHG emissions are not proportionately high. In fact, these are considerably lower: around 2.7% for CO2 and 7% for CH4 (all sources). The energy sector dominated the emissions in these countries followed by agriculture, industrial processes and waste degradation. The forestry sector was a net sink for GHGs in 1990 in these countries. Agriculture is an important source of GHG emissions in this region. In terms of CO2-equivalent, 87% of emissions are in the form of CH4. In the agriculture sector, rice cultivation and enteric fermentation account for 51% and 32% respectively and the remaining portion is contributed by agriculture soils, manure management and field burning of agriculture residues in ALGAS region.
For all countries in South Asia, the CO2-equivalent of CH4 is high. It is 56% of CO2 emissions from energy and industry for India, but nearly 100% for Bangladesh and over 70% for Pakistan. For the South Asian Region, it amounts to 65%.
A large set of measurements are available for methane emissions from paddy fields, and emitted amount from enteric fermentation, from coal mining and from solid wastes. For paddy fields measurements cover different water regimes and span almost a decade, and they include different cultivars and organic supplements. The long-term data have shown very little variation from year to year for emissions of CH4 from paddy fields. Annual methane emission comes to about 4 Tg/yr (± 20%) from Indian paddy fields (Fig. 1). Global emissions, based on several year's measurements in countries like China, Thailand, Philippines, Indonesia, Vietnam as well as in the USA now indicate a much lower global value of CH4 emission of about 25-30 Tg/yr. For enteric fermentation, emission measurements specific for India are few but do exist. Based on these and on weight and age distributions of cattle population as well as milk yields for dairy cattle, emission from enteric fermentation in India is about 7 Tg/yr for 1990. Emission from coal mining is low (0.4 Tg/yr). Total methane emission is about 14 Tg/yr for 1990 and 2 Tg/yr for 2000. The growth rate of CH4 is much lower than for CO2.
Another set of inventories concerns carbon monoxide (CO). Measurements of CO concentrations are now available at a number of places including several newly established stations (viz. Hanle, Darjeeling, Sunderbans and Port Blair). Emission estimates were also made during three biomass-burning campaigns (slash and burn agriculture cases) in the northeastern and southeastern parts of the country. Estimates of total CO inventory (fossil fuel + biomass) are about 60 Tg/yr for India, lower than those of EDGAR version-2 but closer to version-3. Uncertainties are large and India specific values are available only for few forest species. (Contributions from biomass burning, including rural cooking) are dominant, but estimates for relative contributions differ.
The third set of inventories is for estimates of black carbon and organic carbon, which also have large uncertainties. Several recent measurements in India provide useful values for emission factors for wood, dung and agriculture residues. With these values and interpolation of Cooke et al. estimates, inventories of emissions of black carbon and organic carbon give a total of about 1000 Gg/yr of black carbon for all categories of fossil fuel for 1996-97. Rough estimates are around 300 ± 130 dung cakes 500 ± 250. Total for bio fuels is about 900 ± 490 Gg/yr (Fig. 2).
We have also prepared inventories of GHGs, of CO, and NOx and particulates for two mega-cities, Kolkatta and Delhi (Fig. 3) SPM concentrations are found to be high (above the critical values for residential areas) for several cities in India. CO2 emissions for 1990 have been estimated to be around 13 and 6.5 Tg/yr for Delhi and Kolkatta respectively - the two together amount to about 3% of Indian emissions. Both direct and indirect emissions are included. The two cities contribute to annual emission of 0.1% for CO and 4% for black carbon.