Development of a national methane emission inventory for domestic livestock in Saudi Arabia

The objectives were to develop a national CH₄ emission inventory for domestic livestock in Saudi Arabia and to identify possible mitigation to reduce these emissions. The inventory was developed using data derived from farm surveys and national statistical records in Saudi Arabia from 2003 to 2007, as well as Tier 1 and 2 emission factors for enteric fermentation and manure management as proposed by the Intergovernmental Panel on Climate Change. The national CH₄ emission inventory, developed using Tier 1 default factors, increased from 87,069t in 2003 to 100,971t in 2007, with a CO₂ equivalent of 2,176,735 and 2,524,287t, respectively. The contribution to the inventory varied considerably among provinces, ranging from 0.1% (Northern) to 40.6% (Riyadh) in 2007 when horse data were not included. Among animal species, dairy cattle and sheep were the biggest CH₄ producers (37.7% and 35.5%, respectively), followed by camels (13.4%), goats (11.4%), chickens (1.6%) and horses (0.4%). National CH₄ emissions consisted of 0.87 from enteric fermentation and 0.13 from manure storage. Tier 2 CH₄ emission factors were developed for dairy cattle and sheep, with each species divided into two groups (i.e., specialised high genetic merit and traditional low genetic merit), and each group of cattle and sheep were further divided into subgroups according to their physiological states. These factors for enteric fermentation and manure management were all different from Tier 1 default factors, and resulted in a decrease of 2088t in CH₄ emission inventories (CO₂ equivalent of 52,200t) from cattle and sheep when estimated using Tier 2, rather than Tier 1, factors. In comparison with other countries, the national CH₄ emission inventory from domestic animals in Saudi Arabia is relatively small in terms of CH₄ emissions per unit of land area or human population. These results can be used, with data from other agricultural sectors, to develop a national greenhouse gas inventory for the entire agricultural sector of Saudi Arabia. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.