- #1
Graeme M
- 325
- 31
I am aware that it is claimed that ruminant farming and animal agriculture more generally are significant contributors to anthropogenic emissions. Here in Australia, for example, about 80% of emissions from the ag sector are from methane and nitrous oxide. Various groups propose finding ways to reduce agricultural emissions in order to mitigate the growing contribution to atmospheric warming from methane. However, farming advocates argue differently, claiming that methane from ruminants is simply part of the biogenic carbon cycle and not a net contributor.
From what I have read, this is true if herd size remains constant - that is, due to the rapid breakdown of methane in the atmosphere and subsequent take-up by plants of the carbon dioxide that results, livestock are simply recycling methane through this process so long as herd size remains stable over and beyond the residence time of methane.
However, the global herd size is increasing and will continue to increase which leads to increasing emissions from manure management, enteric fermentation and other on-farm activities. That suggests that reducing the global herd size, or at least slowing its growth, would help mitigate warming potential from this sector.
More to the point though, surely reducing herd size continuously would further reduce the atmospheric store and further mitigate warming potential? I am told that this would not be the case as the plants eaten by livestock would still grow, still take in CO2 from the atmosphere and still breakdown releasing methane. In effect, they say, even if we eliminated animal agriculture it would make no difference to the effects of methane from the biosphere.
Is this true? Are efforts to reduce methane emissions from livestock really a waste of time?
From what I have read, this is true if herd size remains constant - that is, due to the rapid breakdown of methane in the atmosphere and subsequent take-up by plants of the carbon dioxide that results, livestock are simply recycling methane through this process so long as herd size remains stable over and beyond the residence time of methane.
However, the global herd size is increasing and will continue to increase which leads to increasing emissions from manure management, enteric fermentation and other on-farm activities. That suggests that reducing the global herd size, or at least slowing its growth, would help mitigate warming potential from this sector.
More to the point though, surely reducing herd size continuously would further reduce the atmospheric store and further mitigate warming potential? I am told that this would not be the case as the plants eaten by livestock would still grow, still take in CO2 from the atmosphere and still breakdown releasing methane. In effect, they say, even if we eliminated animal agriculture it would make no difference to the effects of methane from the biosphere.
Is this true? Are efforts to reduce methane emissions from livestock really a waste of time?