Sunday, January 6, 2013

Meat and emissions: can vegetables save the day?

Becoming vegetarian will not help climate change, and it would create many new problems, claims an American professor in animal science.

Despite the widely held belief that animal farming causes disproportionally high levels of global anthropogenic greenhouse gas (GHG) emissions, the concept of vegetarianism as a solution to reduce emissions was challenged by Dr Jude Capper in her address to the Climate Change Research Strategy for Primary Industries conference in Melbourne in November.

An Adjunct Professor of Animal Sciences in the Department of Animal Sciences at Washington State University, Dr Capper describes herself as a “livestock sustainability consultant” who is “passionate about sustainability issues and the role of animal agriculture in helping to feed a hungry world”, so it perhaps not surprising that she supports eating meat.

“Whole-scale vegetarianism is not a solution that will mitigate GHG emissions, but simply a panacea offered at the expense of consumer choice and dietary diversity,” she said.

She paints a picture of a world in which the only livestock would be found in zoos or conservations parks; points out that other resources would be needed to make by products such as leather, fertiliser, tallow and pharmaceuticals, and even asks how we would feed Australia’s 5.75 million pet cats and dogs.

As an extreme side effect, Capper says that, by feeding on the “leftovers” of plant farming, animals convert this to useful protein; without this, the organic material would go to landfill and produce methane (although arguably the biogas from anaerobic decomposition could be collected for use as biogas, or it could be used to make aerobic compost).

The most common argument for reducing meat production stems from calculations that attribute 18% of GHG emissions to animal agriculture [Livestock’s Long Shadow, UN Food and Agriculture Organisation, 2006]. Capper points to admissions by the report’s author that this figure needs recalculating, however she agrees: “enteric methane emissions are an invariable consequence of ruminant livestock systems, and manure from both ruminant and monogastric animals is a significant contributor to atmospheric methane and nitrous oxide”.

In the USA and elsewhere, ‘Meatless Mondays’ is being promoted as a way of reducing the impact of animal agriculture, however Capper says the “claims for a significant improvement in environmental impact appear to be over-exaggerated”. One claim is by researchers from Carnegie-Mellon University concluding that: “Switching less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs or a vegetable-based diet achieves more greenhouse gas reductions than buying locally-sourced food”.

By Capper’s calculations, based on US EPA figures that red meat and dairy production contributes 3% of annual GHG emissions, if all Americans avoided meat and dairy once a week, this would cut America’s national GHG emissions by just 0.42%, or less (0.29% if only meat was omitted).

The savings could be potentially much higher in Australia, where animal agriculture accounts for 11% of GHG, but 60% of this is exported.

Asked to respond, Sydney PhD student Judith Friedlander, who is researching food sustainability and the media, said that choosing to eat less meat is something effective that consumers can do easily.

She said there was enough evidence to show that meat and dairy production have a substantial impact on emissions and that, while these industries are working to become more efficient, the potential for reduced emissions through technical mitigation options is estimated to be limited to 15-20% (Weidema et al 2008 and Wirsenius and Hedenus 2010): “So a reduction in consumption of livestock and meat products is also vitally important to cut emissions."

Capper disagrees. Despite Stockholm International Water Institute findings that there is not enough water to support the predicted increase in population and that meat consumption will be need to be cut, she points out that dairy production in the US has reduced GHG by 63% and water use by 65% per kg of milk since 1944, while GHG emissions and water use per kg of US beef have dropped by 16% and 12% respectively since 1977.  

Environmentalists often claim that it takes 10, 20 or even 30kg of grain to produce a kilo of beef, Capper resorts to a rather specious argument that corn only accounts for 7% of the feed used to produce a kilo of beef in the USA and, anyway, who wants to eat feed-quality corn? Unfortunately she does not compare the equivalent land use of producing protein-rich chickpeas or soya, although she does make the relevant point that only a small proportion of grazing land is suitable for growing crops. And she highlights the point made by Fairlie (2010) who compared resource use for various diets, that more land would be needed to feed 7 billion people on a vegan diet, due to the lack of animal fertilisers, and the need for more oil-producing plants to replace animal fats.

“Both dairy and grass-fed beef cattle produce a greater amount of human-edible food than they consume,” she argues.

Take the amino acid balance and protein quality of animal proteins compared to plant-based foods, and Capper says: “this strengthens the rational for maintaining omnivorous diets”.

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