The Australian Farm Institute says there is no scientific information that supports the idea reducing meat consumption will significantly reduce global greenhouse emissions.

Institute executive director Mick Keogh says advocates claim meat production is a major source of greenhouse gases, and reducing meat production will lower the risk of dangerous climate change.

He says claims by Rajendra Pachauri, head of the Intergovernmental Panel on Climate Change (IPCC) and a vegetarian, Sir Paul McCartney and Lord Stern of Brentford, author of the Stern Report on climate change, have convinced many in the community that meat production is a major source of greenhouse gases, and the anti-meat bandwagon seems to be quickly gaining new passengers – many of whom are already anti-meat for a range of different reasons.

Keogh says the lack of supporting data and scientific information suggests those advocating “less meat means less heat” may have allowed their personal beliefs about meat consumption to over-ride objective analysis of this issue.

He says IPCC data shows direct emissions from agriculture were estimated to be 13.5% of total man-made emissions in 2004, with agricultural emissions being one of the slowest growing sources of emissions over the period from 1990 to 2007.

Based on IPCC data, Keogh says, direct livestock emissions are estimated to make up about half of total agricultural emissions or only around 7% of global emissions

Methane, belched by ruminants as a digestion byproduct and also a byproduct of manure breakdown, has a global warming potential (GWP) of 21 – meaning a tonne of methane in the atmosphere produces as much warming as 21 tonnes of carbon dioxide over a 100-year period.

Nitrous oxide, released from fertilisers and animal urine, has a GWP of 310.

The relatively high global warming potentials of both these gases mean the production of even relatively small amounts results in significant amounts of emissions when expressed as carbon dioxide equivalents.

Keogh says there is considerable debate about the significance of livestock emissions.

He says there is a downside to using the life cycle analysis (LCA) system for livestock production.

The LCA technique is useful for comparing emission or energy ‘footprints’ of similar products, but is not used for national or international greenhouse accounting.

“The reason is LCA can result in substantial double-counting of emissions and requires a large number of assumptions to be made about indirect emissions associated with production systems, for which data is not available,” Keogh says.

“A further point to note concerning is that it represents gross, rather than net emission estimates for livestock production, with no account taken of the amount of greenhouse gases removed from the atmosphere each year by the plant matter consumed by livestock.”