Methods used to measure greenhouse gas emissions (GHG) have previously shown that intensive, cereal-based cattle production has lower emissions per kg of live weight than extensive grass-based production because the digestion of grain produces less methane per kg of live weight.
However, researchers have now revealed that when the land carbon sequestration of grassland is taken into account, the net carbon emissions of grass-fed production are reduced by up to 94%, which means it produces less emissions than grain-fed systems.
“Using emissions data alone, US feedlot production appeared to be relatively carbon-efficient compared with NT non-intensive and organic farms. This is largely because grain-fed cattle produce less methane, and have shorter life spans than grass-fed cattle,” stated the report’s authors.
“However, when allowance is made for carbon sequestration, the UK and US pasture-based systems in the scenario performed better, in net carbon emissions, than the US feedlot.”
Maximising carbon efficiency alone "too simplistic"
The report also concluded that UK grass-fed beef production has lower GHG emissions than extensive Brazilian beef production, which is largely based in cleared areas of the wooded savannah Cerrado region.
“When carbon release calculated for clearance of the Cerrado for farming is included, the apparently carbon-efficient extensive production from this region looks like one of the most environmentally damaging systems imaginable,” the report stated.
Commenting on the report, Rob Macklin, national agriculture and food adviser at the National Trust, said: “The results are contrary to recent thinking that livestock farming methods must intensify further in order to lessen carbon emissions to feed an ever-increasing world population.
“Maximising carbon efficiency alone is too simplistic. Many less intensive livestock systems would be classed ‘inefficient’ on the carbon emission scale, yet are much less reliant on artificial inputs and tend to have less impacts on water quality, loss of soil organic matter and reduced biodiversity.
“We believe that optimised beef production – deliberately accommodating less than maximum output in order to secure stronger and broader ecosystem protection – is the best sustainable use for the grasslands in our care.”
Livestock essential to environment
He added that the report also demonstrated that a reduction in meat consumption would not necessarily lead to a reduction in carbon emissions. “The debate about climate change and food often calls for a reduction of meat consumption and a more plant-based diet, but this often overlooks the fact that many grasslands are unsuitable for continuous arable cropping,” he said.
“Grasslands support a range of ecosystem services including water resources, biodiversity and carbon capture and storage. Grazing livestock not only contributes to their maintenance but also turns grass into human-edible food.”
The analysis was carried out by Best Foot Forward and Laurence Gould Partnership on behalf of the National Trust. The researchers used the PAS 2050 British Standards Institute (BSI)-approved carbon footprinting standard PAS2050, which incorporates the GHG potency of methane and nitrous oxide emissions using the carbon accounting unit of CO2 equivalent per kg live weight of beef produced (kg CO2e/kg LW).