Reference levels in livestock farming systems: keys to identify the impacts of husbandry (opinion paper)

Baseline use is common in a variety of academic disciplines, including environmental science, but they are subject to relativity depending on the geographical or historical reference considered. The measurement of livestock effects on climate change has, however, disregarded the use of baselines. Greenhouse gas emissions are not put into an ecological context. Grass-fed ruminant systems are hence in the spotlight because of high methane emissions, and conversion into intensive, grain-fed chicken and pork systems is recommended. We reviewed the existing literature on baseline greenhouse gas emissions by wild ruminants, also considering the potential of termites, in filling herbivore niches in an ungulate-free scenario. Natural baseline scenarios would be of the same order of magnitude as current livestock scenarios. Current policy recommendations on livestock sector changes are hence likely to be much less effective than currently thought. Similar considerations can be applied to the impact of livestock on water or biodiversity. Policy recommendations should take baseline levels into account, concentrate on reducing intensive use of fossil fuel and focus on methane reduction with social outcomes, such as the use of manure-fed biogas cooking stoves.