A report which has looked at how to tackle greenhouse gas (GHG) emissions in grazing livestock has highlighted the importance of having an agreed methodology when it comes to calculating the carbon footprint of a farm.

Written by Michael Haverty and James Webster from farm business consultancy firm, The Andersons Centre, the study points to estimates suggesting there are between 60 and 80 different calculators available to quantify emissions from livestock farms.

Within those calculators there are different methods used and significant variation in the results achieved. “There is little wonder, all of this is confusing for the lay person to understand,” states the Andersons report.

In their conclusions, Haverty and Webster suggest that an agreed set of standards on how to calculate a farm’s carbon footprint would be “a major step in developing trust in farm carbon”, adding that it might require an industry wide body to push this through.

Contentious

The work by Andersons also looks at some of the contentious issues around measurement of farm emissions, and does not underestimate the challenge ahead if the UK is to reach net zero GHG emissions by 2050.

That UK commitment is translated into five-year carbon budgets, which started in 2008. The first two budgets have been met, and the third (2018 to 2022) is likely to be achieved, but only just. To meet future targets “will require a change in the way society operates,” suggest Haverty and Webster. “It is arguable that the UK has met its targets up to now by doing the relatively easy things,” they add.

Methane

A significant part of their report looks at the issue of assessing methane from livestock. A potent GHG methane breaks down in the atmosphere, and is reduced to zero after 20 years. So methane released by ruminants today is effectively replacing methane released 20 years ago. Where a cattle and sheep population is stable, methane from these animals does not contribute to global warming.

However, the current accounting system (GWP100) does not recognise that, and instead treats methane the same as carbon dioxide from fossil fuel burning, which lasts in the atmosphere for centuries.

An alternative methodology developed by researchers at Oxford University (GWP*) more accurately reflects the behaviour of methane, and is currently being scrutinised by the Intergovernmental Panel on Climate Change (IPCC).

The Andersons work points out that while 40% of global methane emissions come from ruminants, this is closely followed by emissions related to fossil fuels. “These methane emissions [from fossil fuels] are much more damaging as they are new emissions,” state Haverty and Webster.

They quote a global study which showed that when the GWP100 metric is used, methane accounts for 43% of total GHG emissions from beef, and 42% from dairy. If the alternative GWP* method was deployed, these figures would potentially look significantly different (especially where ruminant numbers are stable).

“The emergence of GWP* may provide some comfort to grazing livestock farming, in that it is not as bad as it has been painted,” states the Andersons report.

That assessment in favour of GWP* is perhaps a little underwhelming, with Haverty and Webster arguing that it would be unwise to argue over “technicalities” too much when society is expecting farming to do its bit on emissions. In particular, farmers will have to do more with less inputs, if the worst effects of climate change are to be avoided, and a growing world population fed.

Sequester

They do accept that farmers in Western Europe have significantly lower emissions per unit of output than the global average. In addition, our grassland can sequester carbon, thereby offsetting some emissions from grazing livestock.

However, there is a limit to which soil carbon levels can be improved, suggest Haverty and Webster. “It should not be seen as a panacea. Additional initiatives are needed,” they argue.

On some farms, that might be a decision to plant woodland, which opens up the possibility to trade the carbon sequestered by trees to big companies looking to offset their emissions. For these farms, they will need to decide whether this carbon offsets their own emissions from farming, or someone else’s – it cannot do both.

But perhaps the most pointed remarks in the Andersons report is directed at the National Farmers’ Union (NFU) and its target for agriculture in England and Wales to hit net zero GHG emissions by 2040.

To achieve that, the NFU rely on emissions reductions that come from higher productive efficiency (making better use of slurry, animal genetics etc.) and by capturing carbon in soils and trees.

However, the biggest GHG savings come from growing energy crops, and then capturing the carbon released when these crops are burned, and storing it underground.

“Some would argue that this is ‘cheating’ as it involves using a technology that has not yet been proven at scale either technically or economically,” state Haverty and Webster.

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