Projection of methane emissions from livestock through enteric fermentation: A case study from India

Livestock is one of the major sources of anthropogenic methane (CH 4 ) emissions. India has the world's largest number of livestock and thus CH 4 emissions from the Indian livestock sector are very significant. Any long-term CH 4 emissions mitigation strategies would require the precise projection of livestock growth, followed by implementation of appropriate policy mechanisms. However, livestock related long-term CH 4 emissions projection studies are currently lacking in India. In this study, a dynamic approach based on the STELLA software in combination with mathematical models was developed to assess livestock population growth and CH 4 emissions in India for a 25 year period (2007–2032) under baseline (BS: BS-I, BS-II, BS-III) and modified (MS: MS-I, MS-II, MS-III) scenarios. Standard Indian livestock database and IPCC emission guidelines were followed to estimate CH 4 emissions. The results indicate that under the baseline scenarios, CH 4 emissions range from 14.08 Tg (296 Tg CO 2 e CH 4 ) in 2007 to 68.49 Tg (1438 Tg CO 2 e CH 4 ) in 2032 and for modified scenarios, emissions range from 13.85 Tg (291 Tg CO 2 e CH 4 ) in 2007 to 16.62 Tg (349 Tg CO 2 e CH 4 ) in 2032. At the state level, the highest CH 4 emissions from livestock has been observed in Uttar Pradesh (15% of total emissions in India) followed by Madhya Pradesh (9.41%) and Andhra Pradesh (9.20%). The lowest emission per head livestock has been observed in goats and sheep (105 kg CO 2 e CH 4 head −1 yr −1 ) followed by cattle (672 kg CO 2 e CH 4 head −1 yr −1 ) and buffalo (1155 kg CO 2 e CH 4 head −1 yr −1 ) in all the scenarios. However, while considering livestock populations, cattle contribute the highest CH 4 emissions (more than 50%) trailed by buffalo, goat, and sheep. Substantial reduction in emissions would be possible if livestock population growth could be stabilized according to the modified scenarios. Different approaches (like dietary management, livestock product demand optimization, and population stabilization) for CH 4 emissions reduction are also discussed in this paper. A comparison of modeled v/s estimated emissions using actual recent livestock census data from year 2012 has also been presented in this paper. The findings of the present study are expected to help policy makers to adopt appropriate policy mechanisms to reduce CH 4 emissions from the Indian livestock sector.