The study shows the favorable evolution of these indicators in Spanish agriculture and livestock farming, as well as the role that the adoption of different agrarian technologies has played in the period from 1980-2008.
In the specific case of livestock farming, the average water consumption throughout the period of the study for drinking and services per kg of porcine and poultry product was found to be 20,4 L/kg of pork, 5,24 L /kg of chicken and y 5,83 L/kg of egg. The total average annual consumption of water for these three productions is 54, 6 and 3 hm3, which together represents a 0,071 % of the total water available in Spain: 89000 hm3.
The average greenhouse gas emissions, including methane as well as nitrous oxide, was found to be 2,45 kg (CO2/kg of pork). In the case of pig farms, a large part of the emissions (67%), correspond to methane derived from manure production. The proportional weight these emissions suppose, together with the national greenhouse gas emissions in 2008 is, on average, 2,50 % (2,07, 0,28 and 0,14 % for swine, poultry and laying birds, respectively).
The estimates obtained for water consumption as well as greenhouse gas emissions are considerably inferior to those that are normally mentioned in the media. The results of this study indicate a decrease throughout the period of the study in both the water consumption and greenhouse gas emissions when expressed as per kg of product obtained.