We think of industry and traffic as the main sources of air pollution and overlook farming and food production.
A new study from the Chinese University of Hong Kong examined the impacts from changing diets and increased meat production in China since the 1980s. Initially, the changes in agricultural production meant more food and better quality food. Undernourishment was reduced and people benefited from fresher fruit and vegetables, and improved animal products. However, continued increases in meat consumption, more processed food and less whole grains have offset these initial gains.
In addition to the direct dietary impacts on health, the quadrupling of China’s meat production between 1980 and 2010 has created an air pollution downside, due to the ammonia from animal waste and the fertilisers used to grow animal feed crops. The air pollution from the agricultural changes was estimated to have caused 90,000 extra deaths in 2010 – 66,000 from the rising demand for meat. People in poorer agricultural areas suffered the greatest effects even though they consumed the least meat.
China is not alone is having air pollution problems from farming. Delhi’s persistently poor air pollution is made worse each year by farmers burning crop waste. In western Europe spring is often the most polluted time of year due in part to the ammonia from farm fertiliser and manure.
Simply reducing meat consumption is one answer. Another is to decrease production. For example, the Dutch government has announced a €25bn (£21bn) programme to buy out cattle farmers.
In his book English Pastoral, James Rebanks describes older mixed-farming methods where animal waste was used on the fields and crops were rotated, reducing the need for artificial fertiliser. A 2018 report by the UK Air Quality Expert Group highlighted that ammonia emissions could be reduced by about 40-60% by better management of manure. This includes covering manure stores, redesigning animal housings and tools to place manure directly on the ground or injecting it in soil rather than splash spreading. Planting trees around animal housings could help by capturing the ammonia and stopping its spread. Up to 40% of the ammonia from chicken farming can be trapped when chickens are kept under tree cover.
A global methane pact was agreed at Cop26, which will increase pressure to reduce air pollutants from agriculture, and especially livestock farming. A growing number of national and local climate assemblies have brought together members of the public to learn, debate and prioritise solutions to the climate emergency. Farmers are great problem solvers. Is it time for a climate, or environment, assembly of farmers?
