Our ‘green’ farming credentials are set to

IRISH production of beef and milk is relatively carbon-efficient on a global scale, although our ranking within the European Union is less clear.

The claim is often made that Ireland is the most carbon-efficient producer of milk in the EU (a position shared with Austria) and the fifth most carbon-efficient producer of beef.

This claim is based on a study by the EU Commission’s Joint Research Centre (JRC). Other available studies do not support such a rosy picture. This is not to say that the JRC results are wrong, but it is useful to understand the reasons why results may differ across studies.

There are an increasing number of studies that investigate the greenhouse gas (GHG) emissions associated with individual farming systems, or which make comparisons between systems (for example, grass-fed versus feedlot beef, conventional versus organic dairy systems).

However, there are very few studies that make international comparisons across countries, including the EU.

In addition to the JRC study which was published in 2010 based on 2004 data, there is a study from Wageningen University published in 2011 based on 2003-2005 data.

International comparisons are also possible using a dataset on emission intensities published by the UN Food and Agriculture Organisation (FAO).

More recently, the FAO has developed a modelling tool called GLEAM (Global Livestock Environmental Assessment Model) which allows comparison of emission intensities across countries. The Wageningen University and FAO studies do not support the claim that Irish beef and milk production is particularly carbon efficient.

The Wageningen University study finds that Irish GHG emissions per kg of milk are the fourth highest in the EU, exceeded only by Poland, Estonia and Bulgaria.

The FAO GLEAM results show that Irish emissions per kg of protein in milk are 50pc higher than the average for producers in Western Europe as a whole.

There are several reasons why different studies might give different results. Some sources are based on activity-based emissions, which is the way emissions are recorded in the annual GHG inventories prepared by each country using IPCC guidelines. Activity-based emissions only consider emissions which are directly associated with the respective activity, such as those associated with rumen fermentation and manure management in cattle.

An alternative approach is called a life cycle assessment (LCA), which examines every step and input during production to calculate a product’s total GHG emissions. This is the approach used to calculate a product’s carbon footprint.

When consumers are making purchasing decisions, they want to know the total environmental impact and not only emissions at an individual stage of production.

A comprehensive LCA for livestock would not only include direct emissions from animals, but also emissions of fodder production in and outside the country and emissions from fertiliser production and transport.

Some studies also include emissions (or removals) from land use and land use change caused by changes in carbon sequestration rates related to feed production (including grassland and grazing).

Teagasc researchers have shown that including the emissions associated with the production of feed reverses the relative carbon efficiency ranking when comparing confinement and grass-based dairy systems.

On an LCA basis, where the full emissions of producing milk including the emissions from producing the feed, the grass-based system turns out