Skip to content Accessibility statement

York scientist at UN summit on farm emissions

Posted on 24 July 2015

An environmental scientist from the Stockholm Environment Institute (SEI) at the University of York contributed to an event at the Milan World EXPO organised by the EU Joint Research Centre in collaboration with scientists from the United Nations Economic Commission for Europe (UNECE) Convention on Long Range Transboundary Air Pollution.

Muck Spreading, Typicca Farm. Credit: George Causley (CC BY-SA 2.0)

Dr Lisa Emberson, Centre Director at SEI in York, discussed measures to target farm emissions to combat air pollution and crop loss.

Focused around the themes ‘feeding the planet’ and ‘energy for life’, experts agreed that measures to reduce agricultural emissions could be the most cost-effective way of tackling threats to global food productivity and human health.

Methane and ammonia emissions are major contributors to the production of dangerous levels of ozone and particulate matter and factor in the premature deaths of millions. Methane, a powerful greenhouse gas is also an important source of ozone which causes global crop losses of US$ 20 billion each year.

According to Dr Emberson and Dr Gina Mills, of the UK’s Centre for Ecology and Hydrology (CEH), ozone air pollution is decreasing food productivity of many major food crops worldwide as global ozone levels rise. This is a particular problem in Asia, where levels of this pollutant sometimes exceed 150 parts per billion – over 10 times natural levels.

Dr Emberson said: “Methane (CH4) is the second most important greenhouse gas and a precursor of ozone, an important air pollutant. Approximately half of all man-made CH4 emissions arise from agriculture, particularly from fermentative digestion by ruminant livestock, storage of manures and emissions from rice paddies".

“The connection between CH4 and ozone formation is perhaps less well-known but equally important. Evidence suggests that high ozone concentrations commonly cause yield losses of between 5 and 15 percent in staple crops over agriculturally important regions in the US Mid-West, Europe, the South Asian Indo-Gangetic plain, as well as over parts of Eastern China”.

“The benefits of reducing CH4 emissions would not only help agricultural productivity but also human health, as ozone can also impair lung function and exacerbate cardio-pulmonary diseases, and near term climate change through reductions in two key greenhouse gasses.”

Dr Markus Amann, of the International Institute of Applied Systems Analysis, Austria, said: “Approximately half of the particulate matter air pollution in Europe comes from unregulated sources. Coordinated EU-wide measures could provide a cost-effective way of reducing the health impacts of particulates.”

Professor Mark Sutton, of the Centre for Ecology and Hydrology, highlighted the major opportunities to improve health, environment and agricultural performance at the same time: “Keeping nitrogen in the farm system can help farmers save on their fertiliser bills, while reducing air pollution, water pollution and greenhouse gas emissions. It can make a major contribution to improving nitrogen efficiency across the world economy”.

“Our food choices also have a huge effect. Traditionally people only ate small amounts of meat, but many of us now consume luxury levels with huge impacts on the planet. Our research points to the need to develop a new food culture in the developed world. One option is to focus on high quality meat raised with the best environmental standards, but to eat it less often and with smaller portion sizes.”

Further information:

  • The United Nations Economic Commission for Europe’s (UNECE) major aim is to promote pan-European economic integration. It brings together 56 countries located in the European Union, non-EU Western and Eastern Europe, South-East Europe and Commonwealth of Independent States (CIS) and North America. All these countries dialogue and cooperate under the aegis of UNECE on economic and sectoral issues. Over 70 international professional organizations and other non-governmental organizations take part in UNECE activities.

  • The Convention on Long-range Transboundary Air Pollution was the first international legally binding instrument to deal with problems of air pollution on a broad regional basis. Signed in 1979 the Convention is one of the central means for protecting our environment. It has substantially contributed to the development of international environmental law and has created the essential framework for controlling and reducing the damage to human health and the environment caused by transboundary air pollution. It is a successful example of what can be achieved through intergovernmental cooperation.

  • In 2014 the Centre for Ecology & Hydrology launched key messages from the developing ‘Nitrogen on the Table’ report by the UNECE Task Force on Reactive Nitrogen ( The full report has now been completed and will be published by CEH this summer.

For more information about the University of York’s Stockholm Environment Institute, visit: 

Media enquiries

David Garner
Head of Media Relations

Tel: +44 (0)1904 322153