3.1 CH4 emission

Using specific emission factors and IPCC Tier 1 methodology, the CH4 emission in India was estimated to be 15.3 Tg CH4 in 2012. CH4 emission related to enteric fermentation is 92% of total CH4 emission (14.20 Tg CH4) and the rest 8% (1.16 Tg CH4) of total CH4 emission from manure management, respectively. Among the livestock groups, the highest CH4 emission is contributed by the cattle group which is nearly 51% of total livestock CH4 emission, and the lowest CH4 emission is contributed by sheep (as shown in Table 3).

Among the 29 states, the top three most emitting states are Uttar Pradesh (2.89 Tg CH4), followed by Rajasthan (1.52 Tg CH4) and Madhya Pradesh (1.30 Tg CH4), and the lowest is in Mizoram (0.018 Tg CH4). The spatial representation of CH4 emission at state level is represented through Figure 2. From the spatial diagram of livestock CH4 emission, it is observed that the major emitting states are distributed across the western and the Indo-Gangetic plains of India. CH4 emission contributions from all the eight northeastern states are only 3.88% of total national emission. The low CH4 emission is due to less livestock population in comparison with the other states. Details of results of different category-wise livestock estimated CH4 emission from each state also shown in Table 4.


#### Table 3.

Climate metric GTP (CH4) for two different time horizons, i.e., 20 and 100 years, is estimated as GTP20 and GTP100 as shown in Eq. (2) in Table 2. These two different assessments are highly significant for the GHGs, which have a shorter lifetime than

where, Ed is the CH4 emission from enteric fermentation and manure management for the ith category

in million; and EFi is the specific emission factor for ith category of livestock in kg CH4 head�<sup>1</sup> year�<sup>1</sup>

GTPdt is GTP of livestock-related CH4 emission for dth district at time "t" (20 or 100 years), kg CO2e; Ed is derived from Eq. 1; GTPt is GTP at "t" time scale, which is equivalent to 67 for 20 year (GTP20)

(3)

time of CH4, 12 years; cj is climate sensitive parameters and dj response times [11]. c1 and c2 are 0.631 and 0.429, respectively; d1 and d2 are 8.4 and 409.5, respectively; e�t=<sup>α</sup> is known as an impulse radiative

; pi is the district wise population of ith category of livestock

) �1 , and t is 20 or 100 year time

; α is perturbation life or e-folding

The AGTP estimates the temperature change (in Kelvin, K) at a time (t) associated with GHG emission as shown in Eq. (3) in Table 2 [11, 12, 21]. The instantaneous surface temperature response (ΔT) is estimated by multiplication of annual CH4 emission and AGTP [22]. Annual ΔT is used for evaluation of the direct temperature effects contributed by an annual rate of CH4 emission over time from

After the estimation of CH4 emission and climate metric assessment from livestock CH4 emission, GIS software, i.e., ArcGIS software, is applied to generation of spatial map for India up to state and district level. The GIS provides better understanding of results in the form of computerized spatial map. For GIS mapping, standard images have been collected from the National Remote Sensing Centre (NRSC), Government of India, for different districts and states of India. Once these standard images of the district level map and state level map of India have been collected, GIS mapping has been prepared. However, district level map could not be prepared for Jammu and Kashmir and represented at state level map, as their

The estimation of CH4 emission from four different livestock categories, cattle, buffalo, goat, and sheep, in India are evaluated at districts, state, and national level using Eq. (1) mentioned in Table 2. In addition to CH4 emission estimation, climate

CO2 and more impact in a shorter time period than longer time horizon.

livestock as shown in Eq. (4) in Table 2.

Equations with their description

of livestock (e.g., dairy cattle) in kg year�<sup>1</sup>

and 4 for 100 year time horizon (GTP100) [11]

j¼1 α�cj α�dj � �

� <sup>e</sup>�t=<sup>α</sup>�<sup>e</sup>

h i � �

AGTPð Þ CH4 <sup>t</sup> is the absolute global temperature potential of CH4, K kg�<sup>1</sup>

horizon; ACH4 is radiative forcing of CH4, 2.1 � <sup>10</sup>�<sup>13</sup> W (kg m<sup>2</sup>

response, K; Ed is CH4 emission attributed by livestock, kg year�<sup>1</sup>

�<sup>t</sup> <sup>=</sup>dj

flux (IRF), i.e., changes in instantaneous radiative flux due to pulse emission of GHGs

An annual CH4 emission (kg) is multiplied by the AGTP values to arrive at the potential of temperature change (ΔT) in a given year (annual AGTP). In the equation, ΔTt is temperature change

Mathematical expression for CH4 estimation and climate metric assessment used in methodology.

<sup>¼</sup>ACH4�∑<sup>2</sup>

ΔTt¼Ed�AGTPð Þ CH<sup>4</sup> <sup>t</sup> (4)

� ��EFi (1)

Climate Change and Agriculture

GTPdt¼Ed�GTPt (2)

Ed¼∑<sup>z</sup> <sup>i</sup>¼<sup>1</sup> pi

AGTPð Þ CH<sup>4</sup> <sup>t</sup>

Table 2.

standard images up to district level are not available.

2.4 GIS map generation

3. Results and discussion

156

National level CH4 (Tg year<sup>1</sup> ) emission from different categories of livestock.

Figure 2. Spatial distribution of CH4 emission from livestock in India at state level.
