Nitrogen pollution, climate and land use: why what we eat matters

Greenhouse gas emissions from agriculture would be cut by 25-40% if Europeans cut their meat and dairy consumption by half, according to a UN report.

Scientists from the UN Economic Commission for Europe say that as well as cutting air and water pollution, adopting a “demitarian diet” – cutting meat and dairy consumption in half – would lead to a 40% cut in Europeans’ intake of saturated fats.

An account of the findings in The Guardian says the vast majority of saturated fats come from animal products that can lead to cholesterol problems and obesity. Such a cut would bring levels to within a range recommended by the World Health Organisation.

Prof Mark Sutton, one of the authors who coined the term demitarian and is one himself, said despite powerful farming lobbies it was not “pie in the sky” to envisage such a cut in meat consumption. But he said the team was not taking a position on how best to encourage people to change their food habits.

“When we’ve seen people urged to be vegetarians I’ve personally seen that that can lead to a backlash because many people want to eat meat. From the environmental point of view, it’s not about whether you eat meat or dairy, it’s about how much,” he said in London on Thursday.

The report, Nitrogen on the Table, examined the impacts that changes in consumer food habits would have on nitrogen emissions from livestock.

The executive summary of the report was published on Friday. The full report will follow next month. It follows a major assessment in 2011 by the same team, which concluded that the annual cost of nitrogen pollution was in the region of £62bn-£282bn.

A press release issued by the Centre for Ecology & Hydrology in the UK quotes the report’s lead author, Henk Westhoek, programme manager for Agriculture and Food at PBL (the Netherlands Environmental Assessment Agency). He said:

“The report shows that the nitrogen footprint of meat and dairy is considerably higher than that from plant-based products. If all people within the EU would halve their meat and dairy consumption, this would reduce greenhouse gas emissions from agriculture by 25 to 40%, and nitrogen emissions by 40%. The EU could become a major exporter of food products, instead of a major importer of for example soy beans.”

The work has been conducted by the ‘Task Force on Reactive Nitrogen’ of the United Nations Economic Commission for Europe (UNECE). In 2011 the Task Force produced the first ‘European Nitrogen Assessment’ (ENA) which showed that better nitrogen management will help reduce air, water and soil pollution, greenhouse gas emissions, simultaneously reducing threats to human health, biodiversity and food security.

Professor Sutton, an Environmental Physicist at the UK’s Centre for Ecology and Hydrology, said:

“Human’s use of nitrogen is a major societal challenge that links environment, food security, and human health. There are many ways in which society could improve the way it uses nitrogen, and this includes actions by farmers and by ourselves. Our new study shows that adopting a demitarian* diet across Europe would reduce nitrogen pollution levels by about 40%, which is similar to what could be achieved by adopting low-emission farming practices.”

The UNECE Task Force on Reactive Nitrogen is tasked with providing policy makers in the Convention on Long-range Transboundary Air Pollution with scientific evidence to support international decision making on environmental policies, especially as these link air pollution with water, soil, climate and biodiversity.

Professor Sutton said:

“As the EU now starts to renegotiate the National Emissions Ceilings Directive, it is an open question to what extent countries will emphasize technical measures or such behavioural changes. One of the major barriers to action is the international trade in food commodities. The result is that countries fear that tackling nitrogen pollution will reduce their international competitiveness. The present study shows that there is huge power for pollution control in simply reducing our meat and dairy consumption.”

Dr Alessandra Di Marco, a co-author of the study and researcher at the Air Pollution Unit of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development, has been involved in a number of food pilot projects in Italian schools.

She said:

“The school food pilot projects in Italy have shown added value environmental benefits and health benefits associated with ‘smart food’. This is a new concept in Italian schools where children are informed about health principle of nutrition, but it still misses the connection with environmental co-benefits of the healthy choice. Increasing the awareness of dietary choice in children is the starting point for cleaning the environment.”

Britain’s Department for Environment, Food and Rural Affairs is working with farmers to reduce greenhouse gas emissions and has launched a £4.5m initiative to help farmers become more environmentally sustainable. The department is four years into an ambitious £12m research programme to improve our understanding of how we can reduce the impact of agriculture on emissions.


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